PNAS

Morphologically controlled synthesis of colloidal upconversion nanophosphors and their shape-directed self-assembly
Xingchen Yea, Joshua E. Collinsb, Yijin Kanga, Jun Chenc, Daniel T. N. Chend, Arjun G. Yodhd, and Christopher B. Murraya,c,1
a Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104; bIntelligent Material Solutions, Inc., Princeton, NJ 08540; cDepartment of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104; and dDepartment of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104
Edited by Louis E. Brus, Columbia University, New York, NY, and approved October 25, 2010 (received for review June 27, 2010)
We report a one-pot chemical approach for the synthesis of highly monodisperse colloidal nanophosphors displaying bright upconversion luminescence under 980 nm excitation. This general method optimizes the synthesis with initial heating rates up to 100 °C∕ minute generating a rich family of nanoscale building blocks with distinct morphologies (spheres, rods, hexagonal prisms, and plates) and upconversion emission tunable through the choice of rare earth dopants. Furthermore, we employ an interfacial assembly strategy to organize these nanocrystals (NCs) into superlattices over multiple length scales facilitating the NC characterization and enabling systematic studies of shape-directed assembly. The global and local ordering of these superstructures is programmed by the precise engineering of individual NC’s size and shape. This dramatically improved nanophosphor synthesis together with insights from shape-directed assembly will advance the investigation of an array of emerging biological and energy-related nanophosphor applications.
doped nanocrystals ∣ superlattice ∣ lanthanides ∣ luminescence
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ecent advances in synthesis and controlled assembly of monodisperse colloidal nanocrystals (NCs) into superlattice structures have enabled their applications in optics (1), electronics (2), magnetic storage (3), etc. Single- and multicomponent superlattices composed of spherical NCs are increasingly studied and a rich family of structures is now accessible (4, 5), where the electronic and magnetic interactions between the constituents gives rise to new cooperative properties (6, 7). New synthetic approaches are yielding nonspherical NCs with physical properties unobtainable by simply tuning the size of the spheres (8–11), providing an even broader array of nanoscale building blocks. The size and shape dependence of NC’s biological activity (12, 13) and toxicity (14) is also of intense interest. However, the challenge of precisely controlling particle shape while maintaining uniformity in size and surface functionality has limited studies of NC environmental health and safety just as it has hindered efforts to organize anisotropic building blocks and to establish methods to capture their unique properties in NC superlattice thin films. Lanthanide-doped nanophosphors are an emerging class of optical materials (15). These NCs often possess “peculiar” optical properties [e.g., quantum cutting (16) and photon upconversion (17)], allowing the management of photons that could benefit a variety of areas including biomedical imaging (18, 19) and therapy (20), photovoltaics (16, 21), solid state lighting (22), and display technologies (23). Colloidal upconversion nanophosphors (UCNPs) are capable of converting long-wavelength near-infrared excitation into short-wavelength visible emission through the long-lived, metastable excited states of the lanthanide dopants (24). In contrast to the Stokes-shifted emissions from semiconductor NCs or organic fluorophores and the multiphoton process employing fluorescent dyes, UCNPs offer several advantages
including narrow emission bands tunable through the choice of dopants (25). With nonblinking emission and remarkable photostablity (18, 26), good brightness under low power continuouswave laser excitation, low autofluorescence background and deep penetration lengths in biological systems, these materials are very attractive for bioimaging applications (18, 19). The hexagonal phase of NaYF4 (β-NaYF4 ) is one of the best host materials for upconversion due to its low phonon energies (27), being several orders of magnitude more efficient than the cubic, α-NaYF4 phase (28). Several chemical approaches including coprecipitation (29) and hydrothermal synthesis (30) have been employed to synthesize β-NaYF4 -based UCNPs. However coprecipitation methods usually necessitate postsynthesis treatments to improve crystallinity of the products, and hydrothermal approaches typically involve long reaction times (ranging from a few hours up to several days) in pressurized reactors (e.g., autoclaves). Importantly, Yan et al. pioneered the synthesis of lanthanide fluoride NCs via the thermal decomposition of metal trifluoroacetate precursors (31, 32). Preparations of β-NaYF4 -based UCNPs through decomposition of mixed trifluoroacetates (33, 34) or through a two-step ripening process using the premade α-NaYF4 NCs as precursors (35) have subsequently been reported. Despite these recent progresses, the crystal quality and monodispersity of the as-synthesized UCNPs using existing recipes are still far from ideal. In this contribution, we report a facile, one-pot method for the shape-controlled synthesis of highly monodisperse β-NaYF4 based UCNPs. Furthermore, we demonstrate that the UCNPs with distinct morphologies (spheres, rods, hexagonal prisms, and plates) can be assembled into large-area superlattices (with individual domain up to ～200 μm2 ) displaying simultaneous positional and orientational order. The symmetry/packing motifs of the superlattices are uniquely determined by the shape of individual NCs. Results and Discussion In this study all β-NaYF4 -based UCNPs are synthesized through thermal decompostion of sodium and lanthanide trifluoroacetates dissolved in a mixture of oleic acid and 1-octadecene. The use of molten salt bath as the heat reservoir ensures uniform heating of the solution that is rapid enough (up to 100 °C∕minute) to overcome the disparity in decompostion temperature among various trifluoroacetate salts (SI Appendix: Fig. S1). Transmission electron microscopy (TEM) images of the UCNPs of various
Author contributions: X.Y., J.E.C., and C.B.M. designed research; X.Y., J.E.C., Y.K., J.C., and D.T.N.C. performed research; A.G.Y. contributed new reagents/analytic tools; X.Y. analyzed data; and X.Y. and C.B.M. wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct Submission.
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To whom correspondence should be addressed. E-mail: cbmurray@https://www.wendangku.net/doc/ff17111825.html,.
This article contains supporting information online at https://www.wendangku.net/doc/ff17111825.html,/lookup/suppl/ doi:10.1073/pnas.1008958107/-/DCSupplemental.
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Fig. 1. TEM images of the β-NaYF4 -based UCNPs. (A, D, G, J) NaYF4 : Yb/Er (20∕2 mol%) UCNPs. (B, E, H, K) NaYF4 : Yb/Tm (22∕0.2 mol%) UCNPs. (F, I) NaYF4 : Yb/ Ho (20∕2 mol%) UCNPs. (C, L) NaYF4 : Yb/Ce/Ho (20∕11∕2 mol%) UCNPs. All scale bars represent 100 nm.
shapes and compositions are shown in Fig. 1. For the case of NaYF4 : Yb/Er (20∕2 mol%)-an optimized composition for efficient upconversion (36), the morphologies of the UCNPs can be tuned from spherical NCs (Fig. 1A), to nanorods (NRs) (Fig. 1D), to hexagonal nanoprisms (Fig. 1G), and finally to hexagonal nanoplates (Fig. 1J) by adjusting the reaction time and/or the ratio of sodium to lanthanide trifluoroacetates. Powder X-ray diffraction (XRD) patterns confirm that all the NaYF4 : Yb/Er (20∕2 mol%) UCNPs are of pure β-NaYF4 phase (Fig. 2A). The XRD patterns of the spherical NCs and the NRs exhibit enhanced (h00) as well as diminished (002) reflections whereas a reversed trend is observed in the case of hexagonal nanoprisms and nanoplates. These results imply that the majority of spherical NCs and NRs are lying with a preference for the [0001] direction (c-axis) parallel to the glass substrates used for XRD while hexagonal nanoprisms and nanoplates are generally sitting with the c-axis perpendicular to the substrates (similar trends are confirmed separately by TEM). High-resolution TEM (HRTEM) image of a single spherical NC shows clear lattice fringes associated with the e10 ˉ 10T, e10 ˉ 11T, and (0001) crystal planes, respectively (Fig. 2B). Lattice fringes corresponding to the (0001) planes appear along the NRs, indicating that the NRs grow along the c-axis (Fig. 2C and SI Appendix: Fig. S2A). HRTEM analysis also reveals that the “cube-like” projections are coming from hexagonal prisms composed of six square or rectangular f10 ˉ 10g side facets with two hexagonal bases belonging to the {0001} planes (Fig. 2D and SI Appendix: Fig. S2B). The formation of NRs and hexagonal nanoprisms is determined by a delicate interplay between the growth rates of {0001} and f10 ˉ 10g planes at different growth stages. This observation contrasts with previous studies where shape evolution of the β-NaYF4 NCs was dominated by controlling the Ostwald-ripening process (35). Furthermore, dynamic light scattering experiments that probe the hydrodynamic size of the dispersed NRs and hexagonal nanoprisms show results consistent with the largest dimensions of individual NCs measured
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from the TEM images (SI Appendix: Fig. S4). In addition, quantitative elemental analyses based on inductively coupled plasma optical emission spectrometry (ICP-OES) indicate the proportional incorporation of precursor lanthanide elements into the final UCNPs (SI Appendix: Table S2). By increasing the sodium to lanthanide ratio and the reaction time, hexagonal nanoplates with an edge length of 133 ? 5 nm and a thickness of 104 ? 8 nm are obtained (Fig. 1J and SI Appendix: Fig. S5). HRTEM image taken from the edge region confirms its high crystallinity (Fig. 2E). Although the present results do not rule out the possibility of cubic to hexagonal (α → β) phase transition very early during the growth, no definitive signature of α phase is observed and the high reaction temperature (～330 °C) favors the formation of β-NaYF4 UCNPs. The NaYF4 : Yb/Er (20∕2 mol%) UCNPs exhibit intense upconversion luminescence under 980 nm excitation (Fig. 2F and SI Appendix: Fig. S6). Three visible emission bands centered at 525, 542, and 655 nm are observed, attributable to the radiative transitions from the (2 H11∕2 , 4 S3∕2 ) (green) and from the 4 F9∕2 (red) excited states to the 4 I15∕2 ground state of Er3t , respectively. The activator Yb3t , capable of absorbing the 980 nm near-infrared light efficiently, transfers its energy sequentially to nearby Er3t through the 2 F5∕2 eYb3t T → 4 I11∕2 eEr3t T process, pumping the Er3t to its emitting levels. The multiphonon relaxation processes help bridge the different excited states of Er3t , giving rise to distinct emission peaks (SI Appendix: Fig. S8). The NaYF4 : Yb/Er (20∕2 mol%) UCNPs obtained display size-dependent optical properties (Fig. 2F and SI Appendix: Fig. S9): Both the total intensity of emission and the intensity ratio of green to red emission increase as NCs get larger. These relationships can be ascribed to the fact that as the size of the NCs decreases, surface defects- and ligands-induced quenching of upconversion become more important, which modifies the relative population among various excited states through phonon-assisted nonradiative relaxations (36). Therefore, engineering not only the dopant conPNAS ∣ December 28, 2010 ∣ vol. 107 ∣ no. 52 ∣ 22431
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Fig. 2. Structural and optical characterization of the β-NaYF4 -based UCNPs. (A) Powder XRD patterns of the NaYF4 : Yb/Er (20∕2 mol%) UCNPs with different shapes. The peaks are indexed according to the standard XRD pattern of β-NaYF4 (JCPDS file number: 28-1192). Insets are the corresponding geometrical models. (B) HRTEM image of a spherical NaYF4 : Yb/Er (20∕2 mol%) UCNP. (C) HRTEM image of a NaYF4 : Yb/Er (20∕2 mol%) NR. (D) HRTEM image of a NaYF4 : Yb/Er (20∕2 mol%) hexagonal nanoprism. (E) HRTEM image taken from the edge of a NaYF4 : Yb/Er (20∕2 mol%) hexagonal nanoplate. (F) Room temperature upconversion emission spectra of the NaYF4 : Yb/Er (20∕2 mol%) and NaYF4 : Yb/Tm (22∕0.2 mol%) UCNPs dispersed in hexane. Inset: Photographs of the upconversion luminescence from the NaYF4 : Yb/Er (20∕2 mol%) (left) and NaYF4 : Yb/Tm (22∕0.2 mol%) (right) NR dispsersions under 980 nm diode laser excitation. (G) Room temperature upconversion emission spectra of the NaYF4 : Yb/Ho (20∕2 mol%) and NaYF4 : Yb/Ho (20∕1 mol%) UCNPs dispersed in hexane. Inset: Photographs of the upconversion luminescence from the NaYF4 : Yb/Ho (20∕2 mol%) nanoprism (left), NaYF4 : Yb/Ho (20∕2 mol%) NR (center) and NaYF4 : Yb/Ho (20∕1 mol%) NR (right) dispersions under 980 nm diode laser excitation.
centration but also the surface functionalities of the UCNPs can be an effective means of tuning the upconversion luminescence. To demonstrate the generality of the synthesis method and further tailor the upconversion emissions, we try several other dopant combinations including Yb/Tm, Yb/Ho, and Yb/Ho/Ce for the β-NaYF4 -based UCNPs. TEM images of the NaYF4 : Yb/Tm (22∕0.2 mol%) UCNPs with different morphologies are shown in Fig. 1B (spherical NCs), Fig. 1E (NRs), Fig. 1H (hexagonal nanoprisms), and Fig. 1K (hexagonal nanoplates), respectively. Upon 980 nm excitation, these hexagonal phase UCNPs (SI Appendix: Fig. S12) emit bright blue upconversion luminescence arising from the trivalent thulium 1 D2 → 3 F4 and 1 G4 → 3 H6 transitions (Fig. 2F). In addition, predominantly green upconversion emissions are observed from the hexagonal phase (SI Appendix: Fig. S14) NaYF4 : Yb/Ho (20∕2 mol%) NRs and nanoprisms UCNPs (Figs. 1 F and I and 2G). The intensity ratio of green to red emission from the NRs increases as the Ho3t concentration increases from 1% to 2%, owing to the enhanced energy transfer from the Yb3t sensitizers to adjacent Ho3t ions (37). Furthermore, trivalent Ce3t ions are introduced to modulate the upconversion profiles of the NaYF4 : Yb/Ho (20∕2 mol%) UCNPs. The parity-allowed 4f → 5d transition in the Ce3t ions can effectively depopulate the green-emitting 5 F4 ∕5 S2 states of Ho3t while increasing the population of the red-emitting 5 F state of Ho3t through two cross-relaxation pathways (SI 5 Appendix: Fig. S8): 5 F4 ∕5 S2 eHo3t T t 2 F5∕2 eCe3t T → 5 F5 eHo3t Tt
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5 F7∕2 eCe3t T and I6 eHo3t T t 2 F5∕2 eCe3t T → 5 I7 eHo3t Tt F7∕2 eCe3t T (38). The as-synthesized NaYF4 : Yb/Ce/Ho (20∕11∕2 mol%) spherical NCs (Fig. 1C) and hexagonal nanoplates (Fig. 1L) display predominantly red emission under 980 nm excitation although the total intensity of emission is much weaker than other UCNPs (SI Appendix: Fig. S15). Powder XRD patterns confirm that both samples are of pure hexagonal phase (SI Appendix: Figs. S16 and S17). The systematic peak shifts to lower angles compared to the standard XRD pattern of β-NaYF4 imply the partial substitution of Y3t ions by larger  Ce3t ions in the β-NaYF4 lattice (Y3t , r ? 1.159 ?; Ce3t ,  r ? 1.283 ?) (39), which results in the expansion of the unit cell. This Ce3t doping differs from previous reports where lanthanide  elements with large ionic radii (e.g., La3t ? 1.300 ?) could not be incorporated into the β-NaYF4 lattice (23). In addition, uniform undoped β-NaYF4 NRs can also be synthesized by the present method (SI Appendix: Fig. S19). Superlattices composed of anisotropic NCs have attracted great interest due to the rich phase behaviors and the potential for emergent collective properties (40). Here we explore the intriguing structural diversity of ordered nanocrystal assemblies using β-NaYF4 NRs and the β-NaYF4 -based UCNPs. We employ an interfacial assembly strategy that can produce continuous and uniform nanocrystal superlattice films (41). When 15 μL of hexane solution of the β-NaYF4 NRs with an aspect ratio (AR) of ～1.4 is drop-cast onto the viscous and weakly polar ethylene glycol (EG) surface and the solvent is allowed to slowly evaporate, large-area NR superlattices comprised of monolayer and doublelayer domains are obtained depending on the concentration of NRs in the dispersion (Fig. 3 A and B). The NRs preferentially align with their c-axis parallel to the substrate, exhibiting both positional and orientation order on the scale of tens of micrometers, as confirmed by the sharp small-angle electron diffraction patterns (SAED). The striking in-plane ordering of the NR superlattices is also revealed by the selected-area wide-angle electron diffraction patterns (SAWED), whose spots are due to diffraction of crystallographic lattice planes. Specifically, the strong (002) diffraction spots are arising from the anisotropic rod-shape of the individual NCs and their mutual alignment along the c-axis. Interestingly, the appearance of (h00) and simultaneous absence of (110) diffraction spots, together with the recognition that the 10g facets, allow us to conβ-NaYF4 NRs are enclosed by the f10 ˉ clude that the NRs are azimuthally aligned along their f10 ˉ 10g crystal facets (SI Appendix: Fig. S22). The superlattice formation is accounted for by the in-plane, dense packing of the β-NaYF4 NRs, possessing a hexagonal cross section and also the interaction of ligands, contributing to the attractions between adjacent NRs. Further evidence that supports the explanation is the lateral displacement between neighboring layers in the β-NaYF4 NR superlattices (SI Appendix: Fig. S23). Liquid crystalline order has been observed in concentrated NR dispersions (42) and NR films prepared by controlled evaporation (43, 44) or by Langmuir-Blodgett assembly (45). Here we have also employed polarizing optical microscope to study the ordering of NR films. Optical micrographs (Fig. 3C and SI Appendix: Fig. S25) indicate domains that are strongly birefringent due to the alignment of NRs. The multidomain nature of the NR films is also confirmed by the atomic force microscopy (AFM). We anticipate that NRs with larger AR (>3) would be better suited for the formation of liquid crystalline phases using the present assembly methodology. β-NaYF4 NRs with an AR of ～2.0 have also been used to study the shape-directed assembly behavior: monolayer and doublelayer superlattices are obtained by depositing 15 μL of NR dispersion (Fig. 4 A and B). However, when 40 μL of NR dispersion is used, the NRs tend to orient vertically in the film with well crystallized domains up to ～200 μm2 (Fig. 4C), as seen from the corresponding SAWED pattern. Each domain is composed of hexagonally closed-packed perpendicularly aligned NRs 2
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Fig. 3. NaYF4 (AR ? 1.4) NR superlattices. (A) TEM image of a monolayer superlattice of NRs that are oriented parallel to the substrate. The upper right inset is the corresponding SAWED pattern and the lower right inset is the corresponding SAED pattern. Both patterns are acquired from an area of ～6.5 μm2 . (B) TEM image of a double-layer superlattice of NRs that are oriented parallel to the substrate. The upper left inset is the high-magnification TEM image acquired from the same domain. The upper right inset is the corresponding SAWED pattern and the lower right inset is the corresponding SAED pattern. Both patterns are acquired from an area of ～6.5 μm2 . (C) Optical micrographs of the NaYF4 (AR ? 1.4) NR superlattices observed with crossed polarizers. The scale bar represents 30 μm. (D) AFM image showing the domain boundaries of the NR superlattices.
(Fig. 4D). This general method to vertically align and assemble NRs maybe of interest for various applications such as photovoltaics (46), plasmonic biosensing (47), and magnetic information storage (3). The ordering of the as-deposited hexagonal nanoprisms and nanoplates superlattices is also strongly dependent on the detailed geometry of individual NCs: In the hexagonal nanoprism assemblies (Fig. 5A and SI Appendix: Fig. S27), each “cube-like”
nanoprism has six neighbors. However, the packing symmetry deviates from the square lattice expected for perfect cubes. The arrangement, in light of recent theoretical work on the packing of fourfold rotationally symmetric superdisks, can be described as the Λ1 -lattice packing (48). Due to the reduced shape symmetry, the hexagonal nanoprisms self-organize into a configuration that maximizes the packing density. On the other hand, hexagonal nanoplates self assemble into close-packed hexagonally ordered
Fig. 4. NaYF4 (AR ? 2.0) NR superlattices. (A) TEM image of a monolayer superlattice of NRs that are oriented parallel to the substrate. The lower right inset is the corresponding SAED pattern acquired from an area of ～2 μm2 . (B) TEM image of a double-layer superlattice of NRs that are oriented parallel to the substrate. The lower right inset is the corresponding SAED pattern acquired from an area of ～2 μm2 . (C) TEM image of a monolayer of vertically aligned NR superlattices. The upper left inset is the high-magnification TEM image showing the hexagonally closed-packed array of NRs. The upper right inset is the corresponding SAWED pattern acquired from an area of ～60 μm2 . (D) TEM image of a closed-packed hexagonally ordered array of vertically aligned NRs. The upper right inset is the corresponding SAWED pattern and the lower right inset is the corresponding SAED pattern. Both patterns are acquired from an area of ～6.5 μm.
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and Er 1,000 ppm ICP standard solutions were purchased from GFS Chemicals, Inc. HoeCF3 COOT3 was purchased from Rare Earth Products, Inc. CeeCF3 COOT3 was prepared according to the literature method (51) using cerium(III) carbonate hydrate (Aldrich) and trifluoroacetic acid (Alfa Aesar) as the precursors. A typical protocol for the synthesis of hexagonal phase NaYF4 -based UCNPs is described below: certain amount of NaeCF3 COOT and REeCF3 COOT3 (see SI Appendix: Table S1 for details) together with 15 mL of ODE and 15 mL of OA were added to a three-necked flask. The mixture was then heated under vacuum at 100 °C for 45 min to form a transparent, yellow solution. The reaction flask was flushed with N2 for 5 min and was then placed into a molten NaNO3 ∕KNO3 (1∶1 mass ratio) salt bath that was stabilized for 342 °C. A large amount of white smoke was produced after about 1.5 min, indicating the decomposition of metal trifluoroacetates (51). After 20–35 min of reaction under N2 flow and vigorous magnetic stirring, the solution was cooled down by adding 15 mL of ODE. The products were isolated by adding ethanol and centrifugation. Due to the mondispersity of the as-synthesized samples, no size-selective fractionation is needed. The UCNPs were redispersed in hexane with nanocrystal concentration of about 5.0 mg∕mL. Assembly of UCNPs into Superlattices. The assembly was done using a variant of the interfacial assembly method recently developed by our group (41). Briefly, a 1.5 × 1.5 × 1 cm3 Teflon well was half-filled with EG. Certain amount of UCNP dispersions (see main text for details) was drop-cast onto the EG surface and the well was then covered by a glass slide to slow down solvent evaporation. After 40 min, the nanocrystal film was transferred onto glass substrates or TEM grids (300-mesh) that was further dried under vacuum to remove extra EG. Structural and Optical Characterization. TEM images and electron diffraction patterns were taken on a JEM-1400 microscope operating at 120 kV. HRTEM images were taken on a JEOL 2010F microscope operating at 200 kV. Scanning electron microscopy (SEM) was performed on a JEOL 7500F HRSEM. Power XRD patterns were obtained on the Rigaku Smartlab diffractometer at a scanning rate of 0.1° min?1 in the 2θ range from 10° to 80° (Cu Kα radiation, λ ? 1.5418 ?). For XRD measurement, samples were prepared by depositing hexane solutions of nanocrystals onto a glass substrate. Dynamic light scattering (DLS) measurements were performed on a Delsa Nano C system (Beckman Coulter). AFM height images were obtained on the DI Multimode AFM. Quantitative elemental analysis was carried out with ICP-OES on a SPECTRO GENESIS ICP spectrometer. Room temperature upconversion emission spectra were acquired with the fiber-optically coupled USB4000 fluorescence spectrometer (Ocean Optics) using an external continuous-wave laser centered at ～980 nm as the excitation source (Dragon Lasers). The optical photographs of the emitting UCNPs were taken using a Nikon D300 digital camera. Nanorod superlattices on glass substrates were imaged under crossed polarizers using a Leica DMRX upright microscope equipped with a charge-coupled device (CCD) camera (Hitachi KP-M1U). ACKNOWLEDGMENTS. We thank Douglas M. Yates and Lolita Rotkina at the Penn Regional Nanotechnology Facility for support in electron microscopy. X.Y. acknowledges primary support from the Department of Energy Basic Energy Science division through award DE-SC0002158 while C.B.M. received partial support for his supervisor role from the Department of Energy Basic Energy Science division through award DE-SC0002158 with secondary support from the National Science Foundation (NSF) Solar initiative through award DMS-0935165. Y.K.’s work on elemental analysis was supported by the Army Research Office (ARO) through MURI W911NF-08-1-0364 and J.C.’s work on structural characterization and analysis was partially supported by the NSF-funded Materials Research Science and Engineering Centers (MRSEC) at the University of Pennsylvania (DMR-0520020). J.E.C. acknowledges the supports from the Nanotechnology Institute of the Commonwealth of Pennsylvania’s Ben Franklin Technology Development Authority and the National Institute of Biomedical Imaging and Bioengineering through the National Institute of Health (NIH) Small Business Technology Transfer (STTR) Phase I grant (Award number: R41EB008959). D.T.N.C. and A.G.Y. acknowledge the financial supports from NSF (DMR-0505048 and MRSEC DMR-0520020) and NASA (NNX08AO0G).
6. Urban JJ, Talapin DV, Shevchenko EV, Kagan CR, Murray CB (2007) Synergism in binary nanocrystal superlattices leads to enhanced p-type conductivity in self-assembled PbTe∕Ag2 Te thin films. Nature Mater 6:115–121. 7. Cheon J, et al. (2006) Magnetic superlattices and their nanoscale phase transition effects. Proc Natl Acad Sci USA 103:3023–3027. 8. Peng XG, et al. (2000) Shape control of CdSe nanocrystals. Nature 404:59–61. 9. Jana NR, Gearheart L, Murphy CJ (2001) Wet chemical synthesis of high aspect ratio cylindrical gold nanorods. J Phys Chem B 105:4065–4067. 10. Sun YG, Xia YN (2002) Shape-controlled synthesis of gold and silver nanoparticles. Science 298:2176–2179.
Fig. 5. Hexagonal nanoprism and nanoplate superlattices. (A) SEM image of a monolayer superlattice of NaYF4 : Yb/Tm (22∕0.2 mol%) hexagonal nanoprisms. The upper right and lower right insets are the high-magnification SEM and TEM images, respectively. (B) SEM image of the self-assembled superlattice of NaYF4 : Yb/Er (20∕2 mol%) hexagonal nanoplates.
arrays (Fig. 5B and SI Appendix: Fig. S28–30), consistent with the sixfold symmetry of nanoplates. Conclusions In summary, we have shown that under different synthetic conditions, NaYF4 -based UCNPs develop regular facets and finally evolve into a diverse family of morphologies (spheres, rods, hexagonal prisms, and plates) in accordance with the underlying hexagonal unit-cell symmetry. Monodisperse UCNPs with distinct shapes are model systems to advance the understanding of the shape-directed assembly/packing behaviors of nanocolloids, but also open new opportunities in fields such as bioimaging (18, 19) and photodynamic therapy (20, 49). Programming anisotropic NCs to assemble into desired two- and three-dimensional patterns enables the production of complex nanoscale architectures useful for applications such as solar cells (46) and plasmonic metamaterials (50). Materials and Methods
Synthesis of Upconversion Nanophosphors (UCNPs). All syntheses were carried out using standard Schlenk techniques. 1-Octadecene (ODE; technical grade, 90%), oleic acid (OA; technical grade, 90%), NaeCF3 COOT and EG were purchased from Sigma Aldrich. REeCF3 COOT3 (RE ? Y, Yb, Er, Tm) and Y, Yb,
1. Tao A, Sinsermsuksakul P, Yang P (2007) Tunable plasmonic lattices of silver nanocrystals. Nature Nanotechnol 2:435–440. 2. Talapin DV, Murray CB (2005) PbSe nanocrystal solids for n- and p-channel thin film field-effect transistors. Science 310:86–89. 3. Sun SH, Murray CB, Weller D, Folks L, Moser A (2000) Monodisperse FePt nanoparticles and ferromagnetic FePt nanocrystal superlattices. Science 287:1989–1992. 4. Shevchenko EV, Talapin DV, Kotov NA, O’Brien S, Murray CB (2006) Structural diversity in binary nanoparticle superlattices. Nature 439:55–59. 5. Talapin DV, et al. (2009) Quasicrystalline order in self-assembled binary nanoparticle superlattices. Nature 461:964–967.
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Ye et al.

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Ye et al.
PNAS ∣ December 28, 2010 ∣
vol. 107 ∣
no. 52 ∣
22435
CHEMISTRY

Supporting Information
Morphologically Controlled Synthesis of Colloidal Upconversion Nanophosphors and Their Shape-Directed Self-Assembly
Xingchen Ye1, Joshua E. Collins2, Yijin Kang1, Jun Chen3, Daniel T.N. Chen4, Arjun G. Yodh4, Christopher B. Murray1, 3, *
1
Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA Intelligent Material Solutions, Inc., 103 Carnegie Center, Princeton, NJ 08540, USA Department of Materials Science and Engineering, University of Pennsylvania,
2
3
Philadelphia, PA 19104, USA
4
Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104,
USA
*
To whom correspondence should be addressed. E-mail: cbmurray@https://www.wendangku.net/doc/ff17111825.html,
1

Table S1. Synthesis Conditions of β-NaYF4-based UCNPs with 342°C salt bath.
Composition
NaYF4:Yb,Er NaYF4:Yb,Er NaYF4:Yb,Er NaYF4:Yb,Er NaYF4:Yb,Tm NaYF4:Yb,Tm NaYF4:Yb,Tm NaYF4:Yb,Tm NaYF4:Yb,Ho NaYF4:Yb,Ho
NaYF4:Yb,Ho,Ce NaYF4:Yb,Ho,Ce
Na(CF3COO) Y(CF3COO)3
6.18mmol 5.62mmol 5.62mmol 6.37mmol 5.90mmol 5.62mmol 5.62mmol 6.37mmol 5.62mmol 5.62mmol 5.62mmol 5.62mmol 4.22mmol 2.60mmol 2.60mmol 2.60mmol 2.60mmol 2.60mmol 2.60mmol 2.60mmol 2.60mmol 2.60mmol 2.60mmol 2.25mmol 2.25mmol 2.23mmol
Dopants
0.68mmol Yb(CF3COO)3 0.068mmol Er(CF3COO)3 0.68mmol Yb(CF3COO)3 0.068mmol Er(CF3COO)3 0.68mmol Yb(CF3COO)3 0.068mmol Er(CF3COO)3 0.68mmol Yb(CF3COO)3 0.068mmol Er(CF3COO)3 0.72mmol Yb(CF3COO)3 0.0072mmol Tm(CF3COO)3 0.72mmol Yb(CF3COO)3 0.0072mmol Tm(CF3COO)3 0.72mmol Yb(CF3COO)3 0.0072mmol Tm(CF3COO)3 0.72mmol Yb(CF3COO)3 0.0072mmol Tm(CF3COO)3 0.68mmol Yb(CF3COO)3 0.068mmol Ho(CF3COO)3 0.68mmol Yb(CF3COO)3 0.068mmol Ho(CF3COO)3 0.68mmol Yb(CF3COO)3 0.068mmol Ho(CF3COO)3 0.36mmol Ce(CF3COO)3 0.68mmol Yb(CF3COO)3 0.068mmol Ho(CF3COO)3 0.36mmol Ce(CF3COO)3
Time
21min 23min 28min 33min 21min 23min 28min 33min 23min 28min 22min 28min
20-22min
Morphology
Sphere Rod Hexagonal Prism Hexagonal Plate Sphere Rod Hexagonal Prism Hexagonal Plate Rod Hexagonal Prism Sphere Hexagonal Plate Rod
NaYF4
None
Note: In this work, we assume that all rare earth trifluoroacetates RE(CF3COO)3 (RE= Y, Yb, Er, Tm, Ce, Ho) are in trihydrate form (i.e., RE(CF3COO)3?3H2O) and Na(CF3COO) is in anhydrous form. Table S2. Quantitative elemental analyses of NaYF4: Yb/Er (20/2 mol%) nanorod and hexagonal nanoprism samples based on ICP-OES. Morphology Rod Hexagonal Prism Y/% 75.0 77.6 Yb/% 23.0 20.4 Er/% 2.0 2.0
2

Fig. S1. Typical reaction temperature profile for the synthesis of β-NaYF4-based UCNPs.?
?
?
Fig. S2. HRTEM images of NaYF4: Yb/Er (20/2 mol%) UCNPs taken along the [0001] direction. (a) Nanorods. (b) Hexagonal nanoprisms.
3

?
Fig. S3. Large-area TEM images of NaYF4: Yb/Er (20/2 mol%) UCNPs. (a) Spherical nanocrystals. (b) Nanorods. (c) Hexagonal nanoprisms. (d) Hexagonal nanoplates.
?
?
Fig. S4. Dynamic light scattering measurements of NaYF4: Yb/Er (20/2 mol%) (a) nanorods and (b) hexagonal nanoprisms dispersed in hexane.
4

?
Fig. S5. SEM images NaYF4: Yb/Er (20/2 mol%) hexagonal nanoplates (edge length:133 ± 5 nm; thickness: 104 ± 8 nm)
Fig. S6. Digital photographs of the reaction flask containing the as-synthesized NaYF4: Yb/Er (20/2 mol%) nanorods without (a) and under (b) 980nm excitation.
5

Fig. S7. (a-e) TEM images at different magnifications and (f) powder XRD pattern of the 17nm spherical NaYF4: Yb/Er (20/2 mol%) nanocrystals synthesized under identical conditions to the spherical NaYF4: Yb/Er (20/2 mol%) nanocrystals listed in Table S1 except 15min of reaction. Inset of (a) is the corresponding SAWED pattern that further confirms the hexagonal phase of the NaYF4: Yb/Er (20/2 mol%) nanocrystals.
6

Fig. S8. Schematic energy level diagram of upconversion processes involving four dopant combinations: Yb-Er, Yb-Tm, Yb-Ho and Yb-Ho-Ce. The dashed, dotted, dashed-dotted, dashdot-dotted and full arrows represent energy transfer, multiphonon relaxation, cross relaxation, photon excitation and emission processes, respectively. The 2S+1LJ notation used to label the energy levels refers to the spin (S), orbital (L) and total (J) angular momentum quantum numbers of the free ions, respectively.
7

Fig. S9. Room temperature upconversion emission spectra of the NaYF4: Yb/Er (20/2 mol%) UCNPs dispersed in hexane under 980nm diode laser excitation (~150 mW). The dimensions of the UCNPs are: (23.0 ± 1.3) nm spherical nanocrystals, (30.3 ± 1.7) nm x (18.0 ± 1.1) nm nanorods, (54.1 ± 2.0) nm x (31.8 ± 1.2) nm hexagonal nanoprisms and (133.0 ± 5.0) nm x (104.0 ± 8.0) nm hexagonal nanoplates, respectively. The concentrations of UCNP solutions are carefully adjusted until the absorbance values around 980 nm (corresponding to the Yb3+ 2F7/2 ? 2 F5/2 transition) are identical. All emission spectra are taken under the same condition.
8

Fig. S10. Large-area TEM images of 25 nm NaYF4: Yb/Tm (22/0.2 mol%) spherical nanocrystals. (a) Monolayer and (b) multi-layer.
9

Fig. S11. Large-area TEM images of NaYF4: Yb/Tm (22/0.2 mol%) (a) nanorods, (c) hexagonal nanoprisms, (e) hexagonal nanoplates and the corresponding HRTEM images (b, d, f).
10

Fig. S12. Powder XRD patterns of NaYF4: Yb/Tm (22/0.2 mol%) (a) nanorods, (b) hexagonal nanoprisms and (c) hexagonal nanoplates.
11

Fig. S13. Large-area TEM images of NaYF4: Yb/Ho (20/2 mol%) (a) nanorods, (c) hexagonal nanoprisms and the corresponding HRTEM images (b, d).
12

Fig. S14. Powder XRD patterns of NaYF4: Yb/Ho (20/2 mol%) (a) nanorods and (b) hexagonal nanoprisms.
13

Fig. S15. Room temperature upconversion emission spectra of the NaYF4: Yb/Ce/Ho (20/11/2 mol%) hexagonal nanoplates dispersed in hexane.
14

SCI投稿需要注意的几个要点

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SCI投稿过程总结、投稿状态解析、拒稿后处理对策及接受后期相关问答综合荟萃目录 （重点是一、二、四、五、六）： （一）投稿前准备工作和需要注意的事项、投稿过程相关经验总结 （二）SCI期刊投稿各种状态详解及实例综合（学习各种投稿状态+投稿经历总结） （三）问答综合篇（是否催稿、如何撤稿、一稿两投及学术不端相关内容等） （四）如何处理审稿意见（回复意见、补实验、润色、重整数据、作图及调整、申辩及其他）（五）Reject 或者Reject and resubmit后的对策和处理 （六）稿件接受后期相关问题（作者信息、地址版权、单行本、彩图费、版面费、如何汇款、清样相关等） （七）进阶篇（如何选投SCI杂志、各专业方向期刊选择、SCI写作经验） （一）投稿前准备工作和需要注意的事项、投稿过程相关经验总结 1)第一作者和通信作者的区别： 通信作者（Corresponding author)通常是实际统筹处理投稿和承担答复审稿意见等工作的主导者，也常是稿件所涉及研究工作的负责人。 通信作者的姓名多位列于论文作者名单的最后（使用符号来标识说明是Corresponding author)，但其贡献不亚于论文的第一作者。 通讯作者往往指课题的总负责人，负责与编辑部的一切通信联系和接受读者的咨询等。 文章的成果是属于通讯作者的，说明思路是通讯作者的，而不是第一作者。 第一作者仅代表是你做的，且是最主要的参与者！ 通信作者标注名称：Corresponding author，To whom correspondence should be addressed,或The person to whom inquiries regarding the paper should be addressed.若两个以上的作者在地位上是相同的，可以采取“共同第一作者”（joint first author)的署名方式，并说明These authors contributed equally to the work。 2)作者地址的标署： 尽可能地给出详细通讯地址，邮政编码。有二位或多位作者，则每一不同的地址应按之中出现的先后顺序列出，并以相应上标符号的形式列出与相应作者的关系。 如果第一作者不是通讯作者，作者应该按期刊的相关规定表达，并提前告诉编辑。期刊大部分以星号（*）、脚注或者致谢形式标注通讯联系人。 3)挑选审稿人的几个途径： 很多SCI杂志都需要作者自己提出该篇论文的和您研究领域相关的审稿人，比较常见的是三名左右，也有的杂志要求5-8人。 介绍几个方法： ①利用SCI、SSCI、A&HCI、ISTP检索和您研究相关的科学家； ②文章中的参考文献； ③相关期刊编委或学术会议的主席、委员； ④以前发表的类似文章的审稿人； ⑤询问比较熟识的一些专业人士； ⑥交叉审稿，邀请以前的作者； ⑦若是团队序贯研究，斟酌考虑自建期刊审稿人专家库。 PS: 如果有熟悉的同领域的专家，可以推荐一两位为宜（若你全部推荐熟人也无可厚非，但编辑基本不会全部考虑，可能对你还有点特殊“眼色”了）。考虑推荐自己文章的参考文献作者较为常用，当然，如果你是负面引用的话，务必慎重了。

投稿写作格式要求

投稿论文格式要求 题名 （居中，一般不宜超过20个字） 作者姓名1，作者姓名2，作者姓名3 （多位作者的署名之间用“，”隔开） （1.作者单位全称，单位所在省份城市邮编；2.作者单位，单位所在省份城市邮编；3. 作者单位，单位所在省份城市邮编） 示例： 熊易群1，贾改莲2，钟晓峰1，刘建军1 （1.山西师范大学教育系，山西太原 030012；2.陕西省教育学院教育系，陕西西安 710061） 摘要为了……，对……进行了研究，报告了……现状，进行了……调查(一般在200字左右，摘要内容包括：目的、过程和方法、内容、研究结果及得出的结论，一定要给出具体的方法、数据指标等具体结果和结论。摘要中不要出现背景信息，内容一定要突显出论文的创新与独特，不要泛泛而谈)。 关键词航天材料；铝合金；力学性能；金属工艺（关键词一般以5～8个为宜，请列出能说明文章主要研究内容的关键词，不要列出放之四海皆准的关键词，如“研究”、“应用”、“工程实践”等，关键词之间用“；”隔开） 作者简介：作者姓名（出生年—），性别，籍贯，何年毕业于何院校，职称，主要从事的工作或者研究，（E-mail） （出生年后用一字线“—”连接） 实例： 作者简介：李晓兰（1968—），女，山西武乡人，1990年毕业于山西矿业学院，高级工程师，主要从事建筑力学与结构力学理论研究，（E-mail）tyut009@https://www.wendangku.net/doc/ff17111825.html, 近年来……(正文五号宋体） 1 一级标题(四号，宋体，加粗) 1.1 二级标题(小四号，宋体，加粗) 1.1.1 三级标题(五号，宋体，加粗) （标题序号后一定要有标题，不能只有序号而无标题；题末不用标点符号，层次一般不超过5级；标题文字一般不超过15个字） 2 科技论文中量和单位的要求 1）量符号必须使用斜体字母。

颗粒物的定义、组成及检测方法

颗粒物的定义、组成及检测方法 颗粒物的定义 颗粒物，又称尘。大气中的固体或液体颗粒状物质。颗粒物可分为一次颗粒物和二次颗粒物。一次颗粒物是由天然污染源和人为污染源释放到大气中直接造成污染的颗粒物，二次颗粒物是由大气中某些污染气体组分（如二氧化硫、氮氧化物、碳氢化合物等）之间，或这些组分与大气中的正常组分（如氧气）之间通过光化学氧化反应、催化氧化反应或其他化学反应转化生成的颗粒物，例如二氧化硫转化生成硫酸盐。 来源 煤和石油燃烧产生的一次颗粒物及其转化生成的二次颗粒物曾在世界上造成多次污染事件。一次颗粒物的天然源产生量每天约 4.41×10^6 吨,人为源每天约0.3×10^6 吨。二次颗粒物的天然源产生量每天约.6×10^6吨,人为源每天约0.37×10^6吨。就总量来说，一次颗粒物和二次颗粒物约各占一半。颗粒物大部分是天然源产生的，但局部地区，如人口集中的大城市和工矿区，人为源产生的数量可能较多。从18世纪末期开始，煤的用量不断增多。20世纪50年代以后，工业、交通迅猛发展，人口益发集中，城市更加扩大，燃料消耗量急剧增加，人为原因造成的颗粒物污染日趋严重。 颗粒物组成 颗粒物的组成十分复杂，而且变动很大。大致可分为三类：有机成分、水溶性成分和水不溶性成分，后两类主要是无机成分。有机成分含量可高达50%（重量），其中大部分是不溶于苯、结构复杂的有机碳化合物。可溶于苯的有机物通常只占10%以下，其中包括脂肪烃、芳烃、多环芳烃和醇、酮、酸、脂等。有一些多环芳烃对人体有致癌作用,如苯并(a)芘等。可溶于水的成分主要有硫酸盐、硝酸盐、氯化物等，其中硫酸盐含量可高达10%左右。颗粒物中不溶于水的成分主要来源于地壳,它能反映土壤中成土母质的特征,主要由硅、铝、铁、钙、镁、钠、钾等元素的氧化物组成。其中二氧化硅的含量约占10～40%，此外还有多种微量和痕量的金属元素，有些对人体有害，如汞、铅、镉等。 浓度测定 在标准状态下（即压力760毫米汞柱,温度为273K）气体每单位体积含尘重量（微克或毫克）数称为含尘浓度。测定方法主要有： 重量法 又叫重量浓度法，采用过滤器或其他分离器收集粉尘并称重的方法，是测定含尘量的可靠方法。过滤器可用滤纸、聚苯乙烯的微滤膜等。有多种测定仪器，如静电降尘重量分析仪可测出低达每标准立方米含尘10微克的浓度。若将已知有效表面积的集尘装置放在露天的适当位置，收集足够量的尘粒进行称重，可测定降尘量。 光散射法 激光粉尘仪具有新世纪国际先进水平的新型内置滤膜在线采样器，仪器在连续监测粉尘浓度的同时，可收集到颗粒物，以便对其成份进行分析，并求出质量

SCI期刊投稿各种状态详解及实例综合

SCI期刊投稿各种状态详解及实例综合（学习各种投稿状态+投稿经历总结） 1.SubmittedtoJournal?刚提交的状态——新手请看这里！！！ 一般的步骤是这样的：网上投稿-Submitamanuscript：先到每个杂志的首页，打开submitpaper 一栏，先以通讯作者的身份register一个账号，然后以authorlogin身份登录，按照提示依次完成：SelectArticleType、EnterTitle、Add/Edit/RemoveAuthors、SubmitAbstract、EnterKeywords、SelectClassifications、EnterComments、RequestEditor、AttachFiles，最后下载pdf，查看无误后，即可到投稿主页approvesubmission或直接submitit。? 总结提示语：对于投稿之前和提交确认投稿过程，这里还需要对投稿新手强调以下几点。因为这些小问题被编辑评个低印象分不划算，被打回也浪费了时间和精力。一条条说来： 1)大多数系统是要求word投稿正文内容的，pdf多不为接受格式。但也有很少数要求用pdf格式的，务必注意细看稿约。 2)文献格式是否按拟投杂志标准要求核准？有的投稿系统是可以直接检查的。 3)引用文献条数是否符合该杂志要求？有的杂志不特别要求，有的还是非常重视的。如我之前投shock杂志，编辑和一位审稿人都提到参考文献不要超过35条。如果你文章写完后，能够适当精简文献条数，那么，请删减几条吧。 4)很多系统要求勾选同意一些如伦理道德的声明文件 5)提交后可能会有一个小栏目提示对提交图片的质量做了初步审查（不合格的最好重新作图再上传） 6)绝大多数投稿完成后需要viewsubmission和最后确认（approvesubmission）。viewsubmission 就是要求你再整体看看投稿填写的这些资料信息+coverletter+正文+图片表格，所生成的pdf全文是否满意、合格，也是你投稿完成前最后一次检查的机会了。 PS：有的新手可能不注意这点，提交后就不管了，还开开心心以为自己投稿成功，殊不知结果邮箱里一直没有收到投稿后的邮件回执和稿号，直到最后纳闷几天了才回去看系统状态。 2.ManuscriptreceivedbyEditorialOffice文章到了编辑手里了，证明投稿成功 3.Witheditor?若投稿时未要求选择编辑，则先到主编处，主编会分派给副主编或者其他编辑。这当中就会有另两个状态：? I)AwaitingEditorAssignment指派责任编辑? II)Editorassigned是把你的文章分给一个编辑处理了。? III)EditorDeclinedInvitation如果编辑接手处理了就会邀请审稿人了。? 总结提示语：一般情况下，投稿（submit）状态后一个星期内会出现编辑处理稿件（witheditor）这个状态。很多老外编辑很不能理解中国人喜欢催稿，绝大多数情况下，他们不会像国内某些期刊一样能拖上一年半载再给屁大点修回意见。要适当给编辑一点时间处理，他们也很忙的。不要轻易催稿，也有人因为催稿而立马收到杯具消息——不知是编辑不耐烦了，还是一种巧合。当然，如果submit四个星期后网上投稿系统还没出现witheditor状态信息，就要询问主编了，要注意委婉用语。不过要注意，也有期刊没有witheditor状态。

多环芳烃

环境中多环芳烃采样罐工作原理 多环芳烃是强致癌物质，可通过接触导致人体致癌。英文简称PAHs。现在已知的500多种致癌物里面，有200多种和多环芳烃有关，现在成为了癌症的代名词。环境大气，室内，包括汽车内饰它无时无刻不存在。 DL-100S型多环芳烃(SVOCs)采样罐配套于DL-6100智能中流量颗粒物采样器，采集环境空气中多环芳烃和半挥发气体（SVOCs） 符合标准： HJ647-2013环境空气和废气气相和颗粒物中多环芳烃的测定高效液相色谱法HJ646-2013环境空气和废气气相和颗粒物中多环芳烃的测定气相色谱-质谱法 PAHS主要来源于自然源和人为源。自然源燃烧(森林大火和火山喷发)和生物合成(沉积物成岩过程、生物转化过程和焦油矿坑内气体)，未开采的煤、石油中也含有大量的多环芳烃。人为源其数量随着工业生产的发展大大增加，占环境中多环芳烃总量的绝大部分;溢油事件也成为PAHs人为源。 青岛动力伟业环保设备DL-100S多环芳烃(SVOCs)采样罐使用说明： 采样装置由采样头、采样泵和流量计组成， 采样泵：具有自动累计流量，自动定时，断电再启功能。正常采样情况下，大流量采样器负载可以达到 225L/min 以上，中流量采样器负载可以达到 100L/min 以上。能够将环境空气抽吸到玻璃纤维滤膜及其后面的吸附材料（包括聚氨酯泡沫+XAD-2 树脂+聚氨酯泡沫）上，在连续采样 24h 期间至少能够采集到 144 m 3 的空气样品。 如果经常接触到多环芳烃会怎么样呢？ 一旦多远方亭进入人体，迅速溶于肾脏、肝脏、脾脏、肾上腺等脂肪组织。虽然会排泄出一些，但是部分残留在体内多环芳烃，组建积累，引发疾病。 采样泵：具有自动累计流量，自动定时，断电再启功能。正常采样情况下，大流量采样器负载可以达到 225L/min 以上，中流量采样器负载可以达到 100L/min 以上。能够将环境空气抽吸到玻璃纤维滤膜及其后面的吸附材料（包括聚氨酯泡沫+XAD-2 树脂+聚氨酯泡沫）上，在连续采样 24h 期间至少能够采集到 144 m 3 的空气样品。 采样头：由滤膜夹和吸附剂套筒两部分组成配备不同的切割器可采集 TSP、PM 10 或 PM 2.5 颗粒物。 滤膜夹包括滤膜固定架、滤膜和不锈钢筛网。滤膜固定架由金属材料制成，并能够通过一个不锈钢筛网支撑架固定玻璃（或石英）纤维滤膜。 吸附剂套筒外筒由聚四氟乙烯或不锈钢材料制成，内部装有玻璃采样筒。 流量计：可设定流量不低于100 L/min，采样前用标准流量计对采样流量进行校准。

投稿邮件格式

电子邮件格式--------------------------------------------------------- 1、正文附件双发送：将邮件内容直接粘贴在邮箱里，并同时说明”附件作为备份”。或联系后确定并登记。 很多媒体电脑装了病毒粉碎机软件，处理邮件时附件一律删除。意味着永远不会被编辑看到。附件格式不同，往往因软件问题 打不开或乱码。打开“附件” 一些病毒是通过附件携带的，除漫画作品外，一般不打开附件；对于doc为了安全，还是用粘贴。 2 那不前功尽弃了吗！有时收 3 4、邮件名称 在邮件主题里标明基本三要素：主题太简单不好，太复杂也不好。 发表笔名，用本名，给编辑坦诚印象。固定笔名，让读者和编辑熟悉！不要花俏。 投稿（有人是建议什么的，这样便于编辑区分！）

投稿版面栏目（便于编辑及时准确地处理。这是加印象分的关键！） 标题与主题。让编辑一眼就看见你的稿子。也一眼就看清有多少同题来稿。 --------------------------------------------------------------------------------------------------------------- 5、邮箱设置 1、设置自动签名一劳永逸！使对方收件箱中直接显示你的名称或笔名。 2、收件人栏不能输入多个地址。 表明作者投稿次数越多。 3 (段首不空格)。可 7、登记档案 1、建立作品档案，详细记录每篇发出、稿费收到时间，记录识别拖沓的媒体。 能上稿，说明这类风格文章被这家媒体接受，可作为重点对象，把类似风格作品发往该媒体。 ------------------------------------------------------------------------

应用稳定碳同位素组成特征研究环境空气颗粒物中多环芳烃的来源

应用稳定碳同位素组成特征研究环境空气颗粒物中多环芳烃的来源 彭林1,白志鹏1,朱坦1,徐永昌2,李剑3,冯银厂1 (1.南开大学环境科学与工程学院,天津　300071;2.中国科学院兰州地质研究所,兰州　730000;3.中国石油勘探开发研究 院廊坊分院,廊坊　065007) 摘要:采集了乌鲁木齐市与郑州市非采暖季的环境空气颗粒物, 用二氯甲烷做溶剂提取、硅胶柱层分离出多环芳烃样品.用气相色谱/燃烧系统/同位素质谱测定了多环芳烃单化合物的稳定碳同位素组成.结果表明:这2个城市的TSP 与PM 10中多环芳烃单化合物稳定碳同位素组成相比较没有明显的区别;两城市的颗粒物样品中,分子量较小菲、蒽、荧蒽、芘和苯并(e )芘的稳定碳同位素组成没有明显的区别,平均值范围为-2314‰～-2418‰,分子量较大的多环芳烃的δ13C 出现了明显差异,乌鲁木齐市环境空气颗粒物中多环芳烃单化合物的δ13C 随着其分子量的增大比郑州市更贫13C ,乌鲁木齐市的环境空气颗粒物中的苯并(a )芘、茚并(1,2,32cd )芘、苯并(ghi ) 的δ13C 值分别为-2813‰、-3118‰和-3012‰,郑州市为-2414‰、 -2914‰和-2613‰.结合对两城市燃煤量和机动车拥有量的对比分析,本研究认为:在非采暖季,这两个城市环境空气颗粒 物中多环芳烃的污染主要是以煤的炭化、气化、燃烧以及机动车尾气为主的复合型污染,而机动车尾气对郑州市环境空气颗粒物中分子量较高的多环芳烃的贡献高于乌鲁木齐市,煤的燃烧对乌鲁木齐市环境空气颗粒物中分子量较高的多环芳烃的贡献高于郑州市. 关键词:稳定碳同位素;多环芳烃;TSP ;PM 10;郑州;乌鲁木齐 中图分类号:X131.1　文献标识码:A 文章编号:025023301(2004)增刊20016205 基金项目:国家自然基金资助项目(20307006)教育部“跨世纪优秀人 才培养计划”基金项目(2002248) 作者简介:彭林(1966～),女,南开大学博士生,副教授,主要从事环 境中有机污染物来源与环境空气颗粒物来源方面的研究.E 2mail :plin123@https://www.wendangku.net/doc/ff17111825.html, Origin of Atmospheric Polycyclic Aromatic H ydrocarbons (PAH s)in Two Chinese Cities Using Compound 2Specif ic Stable C arbon Isotopic Analysis PEN G Lin 1,BAI Zhi 2peng 1,ZHU Tan 1,XU Y ong 2chang 2,L I Jian 3,FEN G Y in 2chang 1 (1.College of Environmental Sciences and Engineering ,Nankai University ,Tianjin 300071,China ;2.K ey Laboratory of G as G eochemisstry ,Lanzhou Institute of G eology ,Chinese Academy of Sciences ,Lanzhou 730000,China ;https://www.wendangku.net/doc/ff17111825.html,ngfang ,Research In 2stitute of Petroleum Exploration &Development ,Langfang 065007,China ) Abstract :Origin of atmospheric polycyclic aromatic hydrocarbons (PAHs )in total sus pended particulate (TSP )and particulate matter ten (PM 10)collected in non 2heating seasons in urban areas of Urumchi and Zhengzhou ,China were discussed on the base of carbon isotopic compositions of individual compounds.Carbon isotope ratios were measured with type of GC 2C 2MS and uncertainty is less than 016‰.δ13C values of atmospheric PAHs in Urumchi range from -2316‰to -3211‰and from -2215‰to -3110‰in Zhengzhou.δ13C values of PAHs in TSP are similar to those in PM 10in the two urban areas.δ13C values of low 2weight molecules (pyrene ,fluoranthene ,benzo [e]pyrene etc.)in PAHs from the two cities are similar ,and the mean value of δ13 C ranged from -2314‰to -2418‰.However ,δ13 C values of high 2weight molecules in PAHs evidently differentiate each other.The individual compounds of atmos pheric PAHs in Urumchi are more depleted in 13C with increasing molecular weight in PAH than those in Zhengzhou.δ13C values of benzo [a ]pyrene ,indeno (1,2,32cd )pyrene and benzo (ghi )perylene in Urumchi were -2813‰,-3118‰and -3012‰,respectively ,which are similar to those of the corresponding molecules in coal combustion particles.The val 2ues of those three compounds in Zhengzhou ,however ,were -2414‰,-2914‰and -2613‰,res pectively ,being similar to those from coal carbonization and automobile exhausts.Our data ,incorporated with the analysis upon the consumption of coal and amount of motor vehicles ,indicate that PAHs were controlled by coal carbonization ,coal combustion and automobile exhausts in two cities ,and contribution of automobile exhausts to PAHs of weight molecular in Zhengzhou is larger than that in Urumchi in no 2heating sea 2son ,while contribution of coal combustion to PAHs of weight molecular in Urumchi is larger than that in Zhengzhou in no 2heating season. K ey w ords :carbon isotope ;polycyclic aromatic hydrocarbons ;TSP ;PM 10;Urumchi ;Zhengzhou 空气颗粒物中存在的多环芳烃(PAHs )主要来源于化石燃料的不完全燃烧,还有少量的PAHs 来源于植物和微生物的内源性合成、森林及草原自然起火、火山活动和一些矿物成分[1].判别空气颗粒 第25卷增刊2004年6月 环 境 科 学ENV IRONM EN TAL SCIENCE Vol.25,Sup.J une ,2004

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论文格式要求 1 板式 纸张大小：纸的尺寸为标准A4复印纸（210mm ×297mm ） 页边距：上3cm ，下3cm ，左3cm ，右3cm ，页眉2cm ，页脚2cm 2 论文撰写必须包括以下项目： 2.1 文章题目（一般不超过20字） 范例： 2.2 范例： （1．珠海市公路建设中心，广东 珠海 2.3 中文摘要、关键词（4~8个）、中图分类号 （1 ）摘要应写成报道式摘要，按照目的、方法、结果、结论四要素来撰写。摘要是以提供文献内容梗概为目的，不加评论和补充解释，简明、确切地记述文献重要内容地短文，避免使用第一人称，应使用第三人称，摘要不分段，字数以200~300字为宜。 （2）关键词的选择应规范。第一个关键词为该文所属相应栏目名称，第二个关键词为该文研究成果名称，第三个关键词为得到该文研究成果所采用的方法名称，第四个关键词为作为该文主要研究对象的事物名称，第五个及以后的关键词为作者认为有利于文献检索的其他名词。 范例： 验，总结了疲劳方程及疲劳曲线，对比分析了3种添加剂稳定的冷再生基层混合料疲劳试验结果，并从疲劳曲线特征及疲劳破坏特征两方面，同普通半刚性材料的疲劳性能进行了比较分析。结果表明，石灰粉煤灰稳定的再生混合料杭疲劳性能最好，其次是水泥粉煤灰，7%水泥稳定的再生混合料杭疲劳性能较差；再生混合料的疲劳特性与普通半刚性材料存在较大差异，在较低 ：道路工程；冷再生混合料；疲劳试验；：U416.26 文献标识码：A 2.4 引言、正文、结语 （1）汉字字体字号选5号宋体，外文、数字字号与同行汉字字号相同，字体用Time New

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