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1.
H. Cherkani-Hassani S. Cherkani-Hassani D. S. Belic J. J. Jureta J. Lecointre P. Defrance 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,58(1):75-83
Absolute cross-sections for electron-impact ionization and dissociation of
C2H2+ and C2D2+ have been measured for electron energies
ranging from the corresponding thresholds up to 2.5 keV. The animated
crossed beams experiment has been used. Light as well as heavy fragment ions
that are produced from the ionization and the dissociation of the target
have been detected for the first time. The maximum of the cross-section for
single ionization is found to be (5.56 ± 0.03)× 10-17 cm2 around 140 eV. Cross-sections for dissociation of C2
H2+ (C2D2+) to ionic products are seen to decrease for two orders
of magnitude, from C2D+ (12.6 ± 0.3) × 10-17 cm2 over CH+(9.55 ± 0.06) × 10-17 cm2,
C+ (6.66 ± 0.05) × 10-17 cm2, C2+ (5.36 ± 0.27) × 10-17 cm2, H+ (4.73 ±
0.29) × 10-17 cm2 and CH2+ (4.56 ± 0.27) × 10-18 cm2 to H2+ (5.68 ± 0.49) ×
10-19 cm2. Absolute
cross-sections and threshold energies have been compared with the scarce
data available in the literature. 相似文献
2.
H. Cherkani-Hassani D. S. Belic J. J. Jureta J. Lecointre P. Defrance 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,58(1):85-94
Absolute cross-sections for electron-impact dissociative ionization of C2
H2+ and C2 D2+ to CH+, C+, C2+ , H+, CH2+
and C2D+ fragments are determined for electron energies ranging
from the corresponding threshold to 2.5 keV. Results obtained in a crossed
beams experiment are analyzed to estimate the contribution of dissociative
ionization to each fragment formation. The dissociative ionization cross
sections are seen to decrease for more than an order of magnitude, from
CH+ (5.37±0.10) × 10-17 cm2 over C+ (4.19±
0.16) × 10-17 cm2, C2D+ (3.94±0.38) ×
10-17 cm2, C2+ (3.82±0.15) × 10-17 cm2
and H+ (3.37±0.21) × 10-17 cm2 to CH2+
(2.66±0.14) × 10-18 cm2. Kinetic energy release
distributions of fragment ions are also determined from the analysis of the
product velocity distribution. Cross section values, threshold energies and
kinetic energies are compared with the data available from the literature.
Conforming to the scheme used in the study of the dissociative excitation of
C2H2+
( C2 D2+ )\left( {\rm C}_2 {\rm D}_2^+ \right), the cross-sections are presented in
a format suitable for their implementation in plasma simulation codes. 相似文献
3.
The frequency (ν = 10?1–107 Hz) dependences σ(ν) of the conductivity of single crystals of the Pb0.67Cd0.33F2 superionic conductor with the fluorite-type structure (CaF2) in the temperature range of 132–395 K have been studied. The dependences σ(ν) have been discussed in the framework of the hopping relaxation of ionic carriers, which are mobile anions F?. From experimental curves σ(ν), the direct-current (dc) conductivity σdc and the average charge carrier hopping frequency νh have been determined. This has made it possible to calculate the charge carrier mobility μmob and charge carrier concentration n mob in these crystals. At room temperature (293 K), the electrical parameters are σdc = 1.6 × 10?4 S/cm, νh = 2.7 × 107 Hz, μmob = 2.0 × 10?7 cm2/(s V), and n mob = 5.1 × 1021 cm?3. 相似文献
4.
We study the optical-gain characteristics of a Si-based MQW laser, in which the active region has 20 Si0.15Ge0.621Sn0.229 quantum wells separated by 20 Si0.637Ge0.018Sn0.345 barriers. We reach a maximum optical gain of 2300 cm?1 with an estimated carrier concentration of 5·1018 cm?3, which is equivalent to the transparent current density equal to 0.5 kA/cm2. Furthermore, we discuss the optical confinement factor and modal gain. The modal gain depends sensitively on the number of the quantum wells (QWs), and this fact restricts the optical confinement factor. The modal gain of the model we proposed can reach 1500 cm?1 at the injection current density equal to 3 kA/cm2. We hope that our results show the possibility to obtain a Si-based near-infrared laser. 相似文献
5.
We have investigated the structural and thermoelectric properties of (Sb1-xBix)2Te3 thin films on CdTe(111)B. Analysis of X-ray diffraction patterns (–2 scans and rocking curves) of the films shows that they are of high quality and that they are well aligned with their (00.1) axis normal to the substrates. Measurements of the temperature-dependent thermoelectric power, resistivity, and Hall coefficient of the films were performed with respect to the binary composition, x. For the samples in the range 0.2<x<0.3, the room-temperature thermopower values were in the range 159–184 V/K, the room-temperature carrier concentrations were 3.93–5.13×1019 cm-3, and the room-temperature mobilities were 24.6–64.0 cm2V-1s-1. PACS 72.20.Pa; 72.80.Jc; 73.6l.Le 相似文献
6.
Silicon isotope separation has been performed utilizing the infrared multiphoton dissociation (IRMPD) of Si2F6 irradiated with two-frequency CO2 laser lights. The two-frequency excitation method improved the separation efficiency by keeping the high enrichment factors. For example, Si2F6 with the 28Si fraction of 99.4% was obtained at 40.0% dissociation of Si2F6 after the simultaneous irradiation of 100 pulses with 966.23 cm-1 photons (0.089 J/cm2) and 954.55 cm-1 photons (0.92 J/cm2), while 1000 pulses were needed to obtain 99.0% of 28Si at 27.2% dissociation in the case of single frequency irradiation at 954.55 cm-1 (0.92 J/cm2). The single-step enrichment factors of 29Si and 30Si increased with increasing Si2F6 pressure. The reason for this enhancement has been discussed in terms of the rotational and vibrational relaxations by collisions with ambient gases. PACS 42.62.Cf; 82.30.Lp; 82.50.Bc 相似文献
7.
A. A. Voronkov B. P. Gorshunov V. S. Nozdrin E. S. Zhukova T. Matsuoka K. Tanaka S. Miyasaka S. Tajima M. Dressel 《JETP Letters》2012,94(9):708-713
The spectra of the conductivity and dielectric constant of La1.87Sr0.13CuO4 cuprate have been directly measured in the frequency range of 0.3 to 1.2 THz (10–40 cm−1) and the temperature range of 5 to 300 K in the E | c polarization (the electric field vector of radiation is perpendicular to the copper-oxygen planes). Excitation has been observed
in the superconducting phase, and its nature has been attributed to the transverse optical excitation of the condensate of
Cooper pairs, which appears because Josephson junctions between CuO planes are modulated due to in-plane magnetic and charge
stripes. Additional quasiparticle absorption of unknown origin has been detected at frequencies below ≈15 cm−1 at liquid helium temperatures. 相似文献
8.
V. P.S. Awana A. Vajpayee M. Mudgel V. Ganesan A. M. Awasthi G. L. Bhalla H. Kishan 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,62(3):281-294
We report synthesis, structure/micro-structure, resistivity under magnetic
field [ρ(T)H], Raman spectra, thermoelectric power S(T), thermal conductivity
κ(T), and magnetization of ambient pressure argon annealed
polycrystalline bulk samples of MgB2, processed under identical
conditions. The compound crystallizes in hexagonal structure with space
group P6/mmm. Transmission electron microscopy (TEM) reveals electron micrographs
showing various types of defect features along with the presence of 3–4 nm
thick amorphous layers forming the grain boundaries of otherwise crystalline
MgB2. Raman spectra of the compound at room temperature exhibited
characteristic phonon peak at 600 cm-1. Superconductivity is observed
at 37.2 K by magnetic susceptibility χ(T), resistivity ρ(T), thermoelectric power
S(T), and thermal conductivity κ(T) measurements. The power law fitting
of ρ(T) give rise to Debye temperature (ΘD) at 1400 K which is
found consistent with the theoretical fitting of S(T), exhibiting Θ
D of 1410 K and carrier density of 3.81 × 1028/m3. Thermal
conductivity κ(T) shows a jump at 38 K, i.e., at Tc, which was
missing in some earlier reports. Critical current density (Jc) of up to
105 A/cm2 in 1–2 T (Tesla) fields at temperatures (T) of up to 10 K
is seen from magnetization measurements. The irreversibility field, defined
as the field related to merging of M(H) loops is found to be 78, 68 and 42 kOe
at 4, 10 and 20 K respectively. The superconducting performance parameters
viz. irreversibility field (Hirr) and critical current density
Jc(H) of the studied MgB2 are improved profoundly with addition of
nano-SiC and nano-diamond. The physical property parameters measured for
polycrystalline MgB2 are compared with earlier reports and a
consolidated insight of various physical properties is presented. 相似文献
9.
Alexander V. Ivanishchev Alexei V. Churikov Irina A. Ivanishcheva Arseni V. Ushakov 《Ionics》2016,22(4):483-501
In order to establish the mechanism and to determine the parameters of lithium transport in electrodes based on lithium-vanadium phosphate (Li3V2(PO4)3), the kinetic model was designed and experimentally tested for joint analysis of electrochemical impedance (EIS), cyclic voltammetry (CV), pulse chronoamperometry (PITT), and chronopotentiometry (GITT) data. It comprises the stages of sequential lithium-ion transfer in the surface layer and the bulk of electrode material’s particles, including accumulation of lithium in the bulk. Transfer processes at both sites are of diffusion nature and differ significantly, both by temporal (characteristic time, τ) and kinetic (diffusion coefficient, D) constants. PITT data analysis provided the following D values for the predominantly lithiated and delithiated forms of the intercalation material: 10?9 and 3 × 10?10 cm2 s?1, respectively, for transfer in the bulk and 10?12 cm2 s?1 for transfer in the thin surface layer of material’s particles. D values extracted from GITT data are in consistency with those obtained from PITT: 3.5–5.8 × 10?10 and 0.9–5 × 10?10 cm2 s?1 (for the current and currentless mode, respectively). The D values obtained from EIS data were 5.5 × 10?10 cm2 s?1 for lithiated (at a potential of 3.5 V) and 2.3 × 10?9 cm2 s?1 for delithiated (at a potential 4.1 V) forms. CV evaluation gave close results: 3 × 10?11 cm2 s?1 for anodic and 3.4 × 10?11 cm2 s?1 for cathodic processes, respectively. The use of complex experimental measurement procedure for combined application of the EIS, PITT, and GITT methods allowed to obtain thermodynamic E,c dependence of Li3V2(PO4)3 electrode, which is not affected by polarization and heterogeneity of lithium concentration in the intercalate. 相似文献
10.
Z. Zhu J. Li A. Brenier G. Jia Z. You X. Lu B. Wu C. Tu 《Applied physics. B, Lasers and optics》2007,86(1):71-75
Yb3+:GdAl3(BO3)4 (hereafter Yb3+:GAB) crystals with large sizes and good optical quality have been grown by the top-seed solution growth (TSSG) method. The polarized absorption and emission spectra have been investigated at room temperature. For the σ-polarization, the intensities of both absorption and emission spectra are stronger than those for the π-polarization, the σ-absorption cross section of Yb3+ in GAB being 3.43×10-20 cm2 at 977 nm, and the σ-emission cross section being 0.98×10-20 cm2 at 1045 nm. The fluorescence lifetime of the 2
F
5/2→2
F
7/2 transition was measured to be 800 μs in the 5% doped sample used for our laser experiments, 993 μs in a 10% doped sample and 569 μs in a 0.5% doped sample. The laser parameters were estimated as: βmin=0.022, Isat=10.4 kW/cm2 and Imin=0.23 kW/cm2. About 0.4 W laseroutput at the wavelength of 1043 nm was achieved when the Yb3+:GAB crystal was pumped by a 974 nm laser diode, with 27.4% slope efficiency. PACS 42.55.-f; 42.70.Hj; 78.20.-e; 81.10.Dn 相似文献
11.
J. Lecointre D. S. Belic J. J. Jureta R. K. Janev P. Defrance 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,55(3):569-580
Absolute cross-sections have been measured for electron-impact dissociative
excitation and ionization of CD2+ leading to
formation of CD22+, CD+, C+,
D2+ and D+. The animated crossed-beams method
is applied in the energy range from the reaction threshold up to 2.5 keV.
The maximum total cross-sections are found to be (1.2±0.1)×10-17 cm2, (6.1±0.7)×10-17 cm2, (6.4±0.7)×10-17 cm2, (26.3±3.8)×10-19 cm2 and (14.9±1.4)×10-17 cm2 for
CD22+, CD+, C+,
D2+ and D+ respectively. Individual
contributions for dissociative excitation and dissociative ionization are
determined for each singly-charged product, which are of significant
interest in fusion plasma edge modelling and diagnostics. Conforming to the
scheme recently applied in the CD4+ and in the
CD3+ articles, the cross-sections are presented in
closed analytic forms convenient for implementation in plasma simulation
codes. Kinetic-energy-release distributions are determined for each ionic
fragment at selected electron energies. 相似文献
12.
O. Silvestre M.C. Pujol M. Rico F. Güell M. Aguiló F. Díaz 《Applied physics. B, Lasers and optics》2007,87(4):707-716
This paper presents the crystal growth and optical characterization of thulium-doped KLu(WO4)2 (KLuW). Thulium-doped KLuW macrodefect-free monoclinic single crystals (a*×b×c≈10×7×15 mm3) were grown by the top seeded solution growth slow cooling method with dopant concentrations of 0.5%, 1%, 3% and 5% atomic
in solution. The evolution of unit cell parameters in relation with thulium doping was studied by X-ray powder patterns. Thulium
energy levels in the KLuW host were determined by 6 K polarized optical absorption. The Judd–Ofelt parameters determined were
Ω2=9.01×10-20 cm2, Ω4=1.36×10-20 cm2 and Ω6=1.43×10-20 cm2. The maximum emission cross section for the 1.9 μm emission, calculated by Füchtbauer–Ladenburg method, is 1.75×10-20 cm2, at 1845 nm with E//Nm. The intensity decay time from the emitting levels 1
G
4 and 3
H
4 levels in relation to the concentration were studied. For the lowest thulium concentration, the measured decay times from
1
G
4 and 3
H
4 emitting levels are 140 μs and 230 μs, respectively.
PACS 42.55.Rz; 78.20.-e; 78.55.-m 相似文献
13.
J. Lecointre D. S. Belic J. J. Jureta R. Janev P. Defrance 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,50(3):265-278
Absolute cross sections for electron-impact dissociative excitation and
ionization of CD+
4 leading to formation of ionic products (CD2+
4, CD+
3, CD+
2, CD+, C+, D+
3, D+
2, and D+) have been measured. The animated crossed-beams
method is applied in the energy range from the reaction threshold up to 2.5 keV. Around 100 eV, the maximum cross sections
are found to be (3.8±0.2) ×10-19 cm2,
cm2,
(7.1±0.8) ×10-17 cm2, (9.0±0.8) ×
10-17 cm2 and (3.7±0.4) ×10-17 cm2 for the
heavy carbonaceous ions CD2+
4, CD+
3, CD+
2, CD+ and C+ respectively. For the light fragments, D+
3, D+
2, and D+, the cross sections around the maximum are
found to be (5.0±0.6) ×10-19 cm2, (1.7±
0.2) ×10-17 cm2 and (10.6±1.0) ×10-17 cm2, respectively. The cross sections are presented in closed analytic
forms convenient for implementation in plasma simulation codes. The analysis
of ionic product velocity distributions allows determination of the kinetic
energy release distributions which are seen to extend from 0 to 9 eV for
heavy fragments, and up to 14 eV for light ones. The comparison of present
energy thresholds and kinetic energy release with available published data
gives information about states contributing to the observed processes.
Individual contributions for dissociative excitation and dissociative
ionization are determined for each detected product. A complete database
including cross sections and energies is compiled for use in fusion
application. 相似文献
14.
Tian Yu Tang Sheng Qiang Ren Yuan Liu Jing Quan Zhang Cai Liu Li Li Wu Wen Wu Wang Wei Li Liang Huan Feng 《Russian Journal of Physical Chemistry B, Focus on Physics》2018,12(3):503-509
Zn2SnO4 (ZTO) is a stable semiconductor in ZnO–SnO2 system and important transparent conducting oxide (TCO) predominantly used in optoelectronic devices. ZTO thin films were prepared by RF magnetron sputtering using Zn2SnO4 ceramic target in this paper. The effects of annealing temperatures and oxygen contents on characterization of ZTO thin films were studied. The results show that ZTO thin films prepared by RF magnetron sputtering are amorphous with an optical band gap of 3.22 eV. After annealing at 650°C in Ar atmosphere for 40 min, ZTO films possess a spinel structure with an optical band gap of 3.62 eV. The atomic force microscope (AFM) data of morphology reveals that the surface roughness of films is about 2 nm. The results of energy dispersive spectrometer (EDS) show that the concentration ratio of Zn to Sn is in the range from 1.44 to 1.57. The results of Hall-effect-measurement system reveal that the resistivity of films varies from 102 to 10–1 Ωcm, carrier concentration is about 1017 cm–3, and mobility ranges from 100 to 101 cm2 v–1 s–1. 相似文献
15.
La0.5Sr0.5CoO3-yttria-stabilized zirconia (LSCO-YSZ) composite cathode for solid oxide fuel cell (SOFC) has been fabricated by wet impregnation method. Nitrate precursors of La, Sr, and Co have been impregnated into the pre-sintered porous YSZ matrix, which is converted into LSCO phase after calcination at 850 °C in the presence of glycine as confirmed from X-ray diffraction. LSCO of 5, 7, and 10 wt% impregnated porous YSZ have been electrochemically characterized using 2-probe AC conductivity method. Maximum ionic conductivity of 0.27 S/cm at 800 °C and activation energy of 0.15 eV between 600 and 800 °C have been observed for 10 wt% LSCO-YSZ cathode. Area-specific resistance of 1.01 Ω cm2 at 800 °C is estimated for the electrolyte-supported half-cell (10 wt% LSCO-YSZ/YSZ). After testing the LSCO-YSZ cathode matrix, the electrolyte-supported full cell (10 wt% LSCO-YSZ/YSZ/NiO-YSZ) has been tested and produced maximum power density 51.12 mW/cm2 (109.38 mA/cm2) at 800 °C. The electrolyte-supported full cell exhibited 6 Ω cm2 electrode polarization at 800 °C in H2, which is in higher side leading to low performance. LSCO-YSZ/YSZ/NiO-YSZ SOFC found to give stable performance up to 2 h and scanning electron microscopy analysis has been carried out before and after cell testing to assess the morphological changes. 相似文献
16.
Y.V. Volk A.M. Malyarevich K.V. Yumashev V.N. Matrosov T.A. Matrosova M.I. Kupchenko 《Applied physics. B, Lasers and optics》2007,88(3):443-447
Anisotropy of the nonlinear absorption of Co2+ ions in MgAl2O4 single crystal at the wavelengths of 1.35 and 1.54 μm has been experimentally demonstrated. The experimental data are analyzed
in the framework of a phenomenological model when the Co2+ ions are described as three sets of linear dipoles oriented along the crystallographic axes. Ground-state and excited state
absorption cross-sections at 1.35 and 1.54 μm are evaluated to be σgsa=(4.0±0.3)×10-19, σesa=(3.6±0.4)×10-20 cm2 and σgsa=(5.1±0.3)×10-19, σesa=(4.6±0.4)×10-20 cm2, respectively.
PACS 42.55.Rz; 71.20.Be 相似文献
17.
X. Chen N.F. Zhuang X.L. Hu F.J. Zhuang J.Z. Chen 《Applied physics. B, Lasers and optics》2007,88(3):449-455
The non-doped and doped Nd3+ of Ca9.03Na1.08La0.62(VO4)7 crystals were grown by the Czochralski technique. The effective segregation coefficients of Na+ and Nd3+ ions in the crystal were measured to be about 0.5 and 1.1, respectively. The XPS analysis of Ca9.03Na1.08La0.62(VO4)7 crystal indicates that the vanadium in the crystal is a mixture of V4+ (1.46 at. %) and V5+ (98.54 at. %). The hardness of Nd:Ca9.03Na1.08La0.62(VO4)7 crystal is about 383.1 VDH. Nd:Ca9.03Na1.08La0.62(VO4)7 crystal exhibits similar thermal expansion coefficients along the a (11.2×10-6 K-1) and c (13.7×10-6 K-1) axes, indicating a low thermal expansion anisotropy (αc/αa≈1.2). The qualitative frequency-doubling experiment shows that the doping of Na+ ion can help reduce the scattering of frequency-doubling light, and the intensity of SHG for Ca9.03Na1.08La0.62(VO4)7 crystal is found to be about 3.5 times as large as that of KDP. The polarized absorption and fluorescence spectra are analyzed
based on Judd–Ofelt theory, which exhibits that the π-polarized absorption and stimulated emission cross sections are 6.07×10-20 cm2 with an FWHM 12.0 nm at 810 nm and 1.42×10-19 cm2 at 1069 nm, respectively. The fluorescence lifetime is 115 μs at room temperature. All the results indicate that Nd:Ca9.03Na1.08La0.62(VO4)7 crystal is a candidate of self-frequency doubling laser material.
PACS 42.62.Fi; 42.70.Mp; 81.10.Fq 相似文献
18.
J.?Lecointre D. S.?Belic J. J.?Jureta R. K.?Janev P.?Defrance 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,55(3):557
Absolute cross-sections have been measured for electron-impact dissociativeexcitation and ionization of CD 2 + leading toformation of CD 2 2+ , CD+, C+,D 2 + and D+. The animated crossed-beams methodis applied in the energy range from the reaction threshold up to 2.5 keV.The maximum total cross-sections are found to be (1.2±0.1)×10-17 cm2, (6.1±0.7)×10-17 cm2, (6.4±0.7)×10-17 cm2, (26.3±3.8)×10-19 cm2 and (14.9±1.4)×10-17 cm2 forCD 2 2+ , CD+, C+,D 2 + and D+ respectively. Individualcontributions for dissociative excitation and dissociative ionization aredetermined for each singly-charged product, which are of significantinterest in fusion plasma edge modelling and diagnostics. Conforming to thescheme recently applied in the CD 4 + and in theCD 3 + articles, the cross-sections are presented inclosed analytic forms convenient for implementation in plasma simulationcodes. Kinetic-energy-release distributions are determined for each ionicfragment at selected electron energies. 相似文献
19.
A Cu2+-doped single crystal of catena-trans-bis(N-(2-hydroxyethyl)-ethylenediamine) zinc(II)-tetra-m-cyanopaladate(II) [ZnPd(CN)4(C4H12N2O2)] complex has been investigated by electron paramagnetic resonance (EPR) technique at room temperature. EPR spectra indicate
that Cu2+ ions substitute for magnetically equivalent Zn2+ ions and form octahedral complexes in [ZnPd(CN)4(C4H12N2O2)] hosts. The crystal field affecting the Cu2+ ion is nearly axial. The optical absorption studies show two bands at 322 nm (30864 cm−1) and 634 nm (15337 cm−1) which confirm the axial symmetry. The spin Hamiltonian parameters and the relevant wave function are determined. 相似文献
20.
A. Li L. Sun Z. Zheng Q. Lü W. Wu W. Liu Y. Yang T. Lü 《Applied physics. B, Lasers and optics》2008,90(1):29-34
The results of the spectroscopic analysis of transition strengths for Er3+ ions in a series of Hf:Er:LiNbO3 crystals with variable Hf content and fixed Er content are reported. Unpolarized UV-VIS-NIR absorption spectra, upconversion
fluorescence spectra excited at 800 nm, and microsecond time-resolved spectra excited at 400 nm and 800 nm by 800 nm femtosecond
laser were measured at room temperature. The HfO2 incorporation has influence on Er3+ radiative lifetimes, and fluorescence branching ratios. For Hf(4 mol %):Er(1 mol %):LiNbO3, Ω2=2.63×10-20 cm2, Ω4=2.86×10-20 cm2, and Ω6=0.72×10-20 cm2. Ω2<Ω4 is contrary to the Er3+ general trend of Ω2>Ω4>Ω6 when the Hf content is below its threshold concentration. In addition, the sum of Ω increases with the Hf content when the
HfO2 content below 6 mol % is unfamiliar. The upconversion mechanism is discussed in this work.
PACS 71.20.Eh; 77.84.Dy; 42.62.Fi; 42.65.Ky 相似文献