共查询到20条相似文献,搜索用时 31 毫秒
1.
ABSTRACT Thermally grown SiO2 thin films on a silicon substrate implanted with 100?keV silicon negative ions with fluences varying from 1?×?1015 to 2?×?1017 ions cm?2 have been investigated using Electron spin resonance, Fourier transforms infrared and Photoluminescence techniques. ESR studies revealed the presence of non-bridging oxygen hole centers, E′-centers and Pb-centers at g-values 2.0087, 2.0052 and 2.0010, respectively. These vacancy defects were found to increase with respect to ion fluence. FTIR spectra showed rocking vibration mode, stretching mode, bending vibration mode, and asymmetrical stretching absorption bands at 460, 614, 800 and 1080?cm?1, respectively. The concentrations of Si–O and Si–Si bonds estimated from the absorption spectra were found to vary between 11.95?×?1021 cm?3 and 5.20?×?1021 cm?3 and between 5.90?×?1021 cm?3 and 3.90?×?1021 cm?3, respectively with an increase in the ion fluence. PL studies revealed the presence of vacancies related to non-bridging oxygen hole centers, which caused the light emission at a wavelength of 720?nm. 相似文献
2.
V. V. Apollonov A. A. Pushkar’ T. V. Uvarova S. P. Chernov 《Physics of the Solid State》2008,50(9):1660-1663
The Dy3+ absorption and excitation spectra of BaY2F8 and BaYb2F8 single crystals are investigated in the ultraviolet, vacuum ultraviolet, and visible ranges at a temperature of 300 K. These crystals exhibit intense broad absorption bands due to the spin-allowed 4f-5d transitions in the range (56–78) × 10?3 cm?1 and less intense absorption bands that correspond to the spin-forbidden transitions in the range (50–56) × 10?3 cm?1. The Nd3+ absorption spectra of BaY2F8 single crystals are studied in the range (34–82) × 10?3 cm?1 at 300 K for different crystal orientations. 相似文献
3.
W.A. Kreiner R. Opferkuch A.G. Robiette P.H. Turner 《Journal of Molecular Spectroscopy》1981,85(2):442-448
The ground-state rotational constants B0, D0, and H0 have been determined for GeH4 from the analysis of ground-state combination differences in the infrared spectra of isotopically enriched 70GeH4, 72GeH4, and 74GeH4. The spectra were recorded at 0.06-cm?1 resolution and about 0.005-cm?1 precision for unblended lines. Suitable combination differences were found in both the ν2 and the ν4 infrared bands. The ground-state constants were assumed to be invariant to isotopic substitution at Ge, and the tensor distortion constants were held fixed at their microwave values. The results obtained are: B0 = 2.69587 ± 0.00007 cm?1, D0 = (3.34 ± 0.03) × 10?5 cm?1, H0 = (1.3 ± 0.5) × 10?9 cm?1. 相似文献
4.
The bending vibration-rotation band ν4 of DCCF was studied. The measurements were carried out with a Fourier spectrometer at a resolution of about 0.03 cm?1. The constants B0=0.29141(1)cm?1, α4=?5.02(2)×10?4cm?1, q4=4.52(3)×10?4cm?1, and D0=9.2(4)×10?8cm?1 were derived. The rotational analysis of the “hot” bands 2ν4(Δ) ← ν4(II) and 2ν4(Σ+) ← ν4(II) was performed. In addition, the “hot” bands ν4 + ν5 ← ν5 were assigned. A set of vibrational constants involved was derived. 相似文献
5.
Ca0.89Y0.11F2.11:Er3+ (CYF:Er) crystals with an erbium content of 1–15 at % have been grown. The optical spectra and luminescence kinetics of CYF:Er crystals have been investigated at low (~5 K) and room temperatures. Based on an analysis of the absorption spectra at low temperature, the structure of Stark splitting of erbium levels in CYF:Er crystals is determined. Room-temperature absorption spectra are used to calculate the spectra of absorption cross sections and oscillator strengths of transitions from the erbium ground state to excited multiplets. It is shown that the absorption spectrum of CYF:Er crystals contains broad bands in the ranges of 790–815 and 965–980 nm, which correspond to the range of emission of laser diodes. For the band peaking near 967 nm, the peak absorption cross section is σ abs max = 2.7 × 10?21 cm2. The intensity parameters are determined by the Judd-Ofelt method to be Ω2 = 1.39 × 10?20, Ω4 = 1.34 × 10?20, and Ω6 = 2.24 × 10?20 cm2. The radiative transition probabilities, radiative lifetimes, and branching ratios are calculated with these values. The luminescence decay kinetics from excited erbium levels upon selective excitation is investigated and the experimental lifetimes of the 4F 9/2, 4 S 3/2, and 4 G 11/2 radiative erbium levels are determined. The dependences of multiphonon relaxation rates on the energy gap in CYF:Er crystals are obtained. The rates of nonradiative multiphonon relaxation from radiative erbium levels are determined. 相似文献
6.
ESR studies were conducted on Cu2+-doped bis-(5,5′-diethylbarbiturato)bis picoline Zn(II). Two Cu2+ lattice sites, Cu2+(I) and Cu2+(II), were identified. These sites exhibit two sets of four hyperfine lines in all directions. The g factor and hyperfine splitting were calculated from ESR absorption spectra: gx ?=?2.0201?±?0.002, gy ?=?2.0900?±?0.002, gz ?=?2.1634?±?0.002, Ax ?=?(30?±?2)?×?10?4?cm?1, Ay ?=?(40?±?2)?×?10?4?cm?1 and Az ?=?(154?±?2)?×?10?4?cm?1. It was found that Cu2+ enters the lattice substitutionally. The ground-state wavefunction of the Cu2+ ion in this lattice was determined from the spin Hamiltonian constants obtained from the ESR studies. With the help of an optical absorption study, the nature of the bonding in the complex is also discussed. 相似文献
7.
The high-information Fourier interferometer built at Laboratoire Aimé Cotton has been modified in order to extend the spectral range. It is now possible to record spectra in the Indium Antimonide region with an apodized resolution of 5 × 10?3 cm?1. Nitrous oxide vibration-rotation bands between 1800 and 3200 cm?1 have been measured and analyzed and rotational constants for 33 bands have been calculated. 相似文献
8.
Abstract Three new bands of the B 2Σ+–X 2Σ+ system of 12C17O+ have been investigated using conventional spectroscopic techniques. The spectra were observed in a graphite hollow‐cathode lamp by discharging molecular oxygen (enriched in about 45% of the 17O2 isotope) under 1.0 Torr pressure. The rotational analysis of the 2–4, 2–5, and 2–6 bands was performed with the effective Hamiltonian of Brown (Brown et al., J. Mol. Spectrosc. 1979; 74: 294–318). Molecular constants were derived from a merge calculation, including both the current wavenumbers and the spectroscopic data published by the authors previously. The principal equilibrium constants for the ground state of 12C17O+ are ωe=2185.9658(84), ωe x e = 14.7674(11), B e=1.927001(38), αe=1.8236(22)×10?2, γe=?0.331(28)×10?4, D e=6.041(12)×10?6, βe=0.100(31)×10?7 cm?1, and the equilibrium constants for the excited state are σe=45876.499(15), ωe=1712.201(12), ωe x e=27.3528(39), B e=1.754109(35), αe=2.8706(57)×10?2, γe = ?1.15(19)×10?4, D e=7.491(20)×10?6, βe=2.13(12)×10?7, γe = 2.0953(97)×10?2, and αγe=?9.46(59)×10?4 cm?1, respectively. Rydberg–Klein–Rees potential energy curves were constructed for the B 2Σ+ and X 2Σ+ states of this molecule, and Franck–Condon factors were calculated for the vibrational bands of the B–X system. 相似文献
9.
Na0.4Y0.6F2.2:Tm3+ crystals with a thulium content from 1 to 100 at % have been grown by the Stockbarger-Bridgman method. The optical spectra of Na0.4Y0.6F2.2:Tm3+ crystals were investigated in detail at room and low (10 K) temperatures, and the luminescence kinetics was analyzed using different excitation methods. The structure of the Stark splitting of thulium levels as “quasi-centers,” characterized by inhomogeneous broadening of the Stark components, is determined from analysis of the absorption spectrum at 10 K. The oscillator strengths of the transitions from the ground state to excited multiplets are determined from the absorption cross-section spectra at 300 K for ten transitions in the range 5000–38 500 cm?1 and seven transitions in the range 5000–28 500 cm?1. The transition intensity parameters Ω t , obtained by the Judd-Ofelt method from the spectra due to the transitions to ten and seven excited levels, were found to be, respectively, (i) Ω2 = 1.89 × 10?20, Ω4 = 2.16 × 10?20, and Ω6 = 1.40 × 10?20 cm2 and (ii) Ω2 = 2.04 × 10?20, Ω4 = 2.01 × 10?20, and Ω6 = 1.44 × 10?20 cm2. These values of the intensity parameters were used to calculate the radiative transition probabilities and branching ratios and to estimate the multiphonon nonradiative transition probabilities for NYF:Tm. The luminescence decay kinetics from thulium radiative levels upon their selective excitation by nanosecond laser pulses has been studied and the lifetimes of thulium radiative levels in NYF crystals have been found. 相似文献
10.
L. A. Zhigula V. A. Kondaurov I. S. Fedorov D. N. Shchepkin 《Optics and Spectroscopy》2007,103(4):603-613
The vibrational spectrum of CF3Br with the natural abundance ratio of isotopologues is studied in solutions in liquid Ar at T = 90 K in the frequency range 4000–400 cm?1 with a resolution of 0.1 cm?1 for the concentration range 3.1 × 10?7?6.3 × 10?3 mol %. The parameters of the vibrational spectrum of the molecule are determined: the frequencies are measured accurate to ± 0.1 cm?1, and the transition probabilities are found up to the fourth order inclusive. One hundred fifty absorption bands of CF3Br are interpreted, including the bands belonging to all the isotope modifications of this compound; the halfwidths of these bands are determined. For all the fundamental frequencies, the isotope shifts are obtained. Vibrational ?-resonance is studied. Using the experimental data obtained and taking into account this resonance, a complete set of parameters describing the experimental frequencies with the error δ ≈ 0.3 cm?1 was found. This set consists of 6 harmonic frequencies and 30 anharmonicity constants, including the constants r ik related to vibrational ?-resonances. 相似文献
11.
《Molecular physics》2012,110(21-22):2665-2671
Near infrared spectra of a carbon dioxide sample enriched with oxygen-17 have been recorded using a high-resolution continuous scan Fourier transform interferometer fitted with a femto OPO/Idler laser source. Cavity enhanced absorption has been achieved in a static gas cell allowing an optimal rms noise equivalent absorption of 1.2?×?10?10?cm?1?Hz?1/2 per spectral element to be reached, corresponding to αmin?=?10?8?cm?1. Spectra were calibrated against acetylene reference line positions. Three bands in the 3ν1?+?ν3 tetrad in both 12C17O2 and 12C17O18O have been identified and rotationally analyzed, as well as some related hot bands, eight of which are newly reported and three with their analysis updated compared with a preliminary report (X. de Ghellinck d’Elseghem Vaernewijck et al., Chem. Phys. Lett. 514, 29 (2011)). 相似文献
12.
X-band electron paramagnetic resonance (EPR) study of Cr3+-doped dipotassium tetrachloropalladate single crystal is done at liquid nitrogen temperature. EPR spectrum shows two sites. The spin-Hamiltonian parameters have been evaluated by employing hyperfine resonance lines observed in EPR spectra for different orientations of crystal in externally applied magnetic field. The values of spin-Hamiltonian and zero-field splitting (ZFS) parameters of Cr3+ ion-doped DTP for site I are: g x = 2.096 ± 0.002, g y = 2.167 ± 0.002, g z = 2.220 ± 0.002, D = (89 ± 2) × 10?4 cm?1, E = (16 ± 2) × 10?4 cm?1. EPR study indicates that Cr3+ ion enters the host lattice substitutionally replacing K+ ion and local site symmetry reduces to orthorhombic. Optical absorption spectra are recorded at room temperature. From the optical absorption study, the Racah parameters (B = 521 cm?1, C = 2,861 cm?1), cubic crystal field splitting parameter (Dq = 1,851 cm?1) and nephelauxetic parameters (h = 2.06, k = 0.21) are determined. These parameters together with EPR data are used to discuss the nature of bonding in the crystal. 相似文献
13.
J. Cahen-de Villardi M. Clerc P. Isnard J.M. Weulersse 《Journal of Molecular Spectroscopy》1980,84(2):319-333
Coherent Stokes and anti-Stokes Raman scattering are used to study the ν1 and ν2 spectral band profiles of UF6 and SF6. Most of the observed SF6 “hot” bands are assigned, leading to evaluations of the anharmonicity constants Xij: X12 = ?(2.80 ± 0.30) cm?1, X14 = ?(1.00 ± 0.15) cm?1, X15 = ?(1.00 ± 0.15) cm?1. For UF6, a tentative assignment of the “hot” bands is made: X12 = ?(1.80 ± 0.30) cm?1, X13 = ?(1.60 ± 0.30) cm?1, X14 = ?(0.20 ± 0.10) cm?1, X15 = ?(0.25 ± 0.10) cm?1, and X16 = ?(0.10 ± 0.05) cm?1. Parameters such as the vibration-rotation coupling constants are determined. For SF6: α = (7 ± 2) × 10?5 cm?1 for the ν2 band and α = ?(1.02 ± 0.01) 10?4 cm?1 for the ν1 band. The calculated spectral profiles of the coherent Stokes or anti-Stokes spectra, which are in good agreement with experimental results, give values for the resonant and nonresonant parts of the susceptibility in both molecules. They also show, in some cases, the influence of neighboring combination bands. 相似文献
14.
I. S. Edelman O. B. Romanova L. I. Ryabinkina G. M. Abramova V. V. Markov 《Physics of the Solid State》2001,43(8):1549-1551
The optical absorption spectra of an α-MnS single crystal and their temperature behavior in the range from 86 to 300 K are investigated for the (100) plane in the energy range from 8×103 to 22×103 cm?1 for the first time. Comparison of these spectra with those for the (111) plane reveals an essential absorption anisotropy in unpolarized light. The anisotropy is manifested in a much stronger splitting of the lowest energy band for the (100) plane in comparison with that for the (111) plane. With decreasing temperature, the splitting becomes smaller. Possible mechanisms for the anisotropy revealed are proposed. 相似文献
15.
F. F. Komarov A. V. Mudryi L. A. Vlasukova N. I. Mukhurov A. V. Ivanyukovich 《Optics and Spectroscopy》2008,104(2):235-237
The luminescence spectra of aluminum oxide with an ordered system of through pores have been studied. The diameter and density of pores were ≈ 50 nm and 1.2 × 1010 cm?2, respectively. Amorphous aluminum oxide formed by anodization of aluminum foil in an oxalic acid electrolyte shows intense luminescence in the blue spectral region. Processing of spectra with the use of an oxalic acid approximation by Gaussian curves gives three bands peaking at ~ 382 (3.2 eV), 461 (2.7 eV), and 500 nm (2.5 eV), which correspond to different types of defects. The bands at 382 and 461 nm can be assigned to optical transitions involving F+ and F centers (vacancies of oxygen with one or two electrons), respectively. The lower-energy band near 500 nm can be presumably assigned to luminescence from F++ centers (vacancy of oxygen without an electron). Analysis of the luminescence excitation spectra has revealed an inhomogeneous character of the distribution of the corresponding luminescence centers in the Al2O3 matrix. 相似文献
16.
The rate of transfer of electrons from O2 to O2+ and O3+ has been measured at energies ? 2 eV using a stored ion technique. The rate for O2+ is k = 1.0(0.3) × 10?9 cm3/s and for O3+, k = 2.5(0.3) × 10?9 cm3/s, compared to calculated Langevin rates of 1.8 × 10?9 cm3/s and 2.7 × 10?9 cm3/s respectively. 相似文献
17.
The infrared spectral characteristics of ordered mixed-layer illite/smectite interstratified clay mineral with different mixed-layer ratios (S% = 5%, 10%, 15%, 20%, 25%, and 30%, where S% is mixed-layer ratio) from the Shihezi Formation of Late Permian in the Hanxing mining area, Hebei province of China, were studied by infrared spectroscopy. The results show that three infrared regions (3625 cm?1±, 1200–1000 cm?1, 850–700 cm?1) changed with S%'s variation. The characteristic absorption bands of smectite at 3640 cm?1, 1030 cm?1, and 825 cm?1 disappeared gradually with the decrease of S%, and the intensity of characteristic absorption bands of illite at 3625 cm?1, 1100 cm?1, 1024 cm?1, 796 cm?1, and 777 cm?1 increased. These changes indicated that the illitization of smectite was realized by partial substitution of aluminum iron (Al3+) for silicon iron (Si4+) in silico-oxygen (Si–O) tetrahedron. 相似文献
18.
Lakhwant Singh 《Journal of Macromolecular Science: Physics》2013,52(5):1041-1049
Polycarbonate (Makrofol‐N) thin films were irradiated with protons (3 MeV) under vacuum at room temperature with the fluence ranging from 1×1014 to 1×1015 protons cm?2. The change in surface morphology, optical properties, degradation of the functional groups, and crystallinity of the proton‐irradiated polymers were investigated with atomic force microscopy (AFM), UV‐VIS, and Fourier‐transform infrared (FTIR) spectroscopy, and X‐ray diffraction (XRD) techniques, respectively. AFM shows that the root mean square (RMS) roughness of the irradiated polycarbonate surface increases with the increment of ion fluence. The UV‐VIS analysis revealed that in Makrofol‐N the optical band gap decreased by 30% at highest fluence of 1×1015 protons cm?2. The band gap can be correlated to the number of carbon atoms, M, in a cluster with a modified Robertson's equation. The cluster size in the proton‐irradiated Makrofol‐N increased from 112 to 129 atoms with the increase of fluence from 1×1014 to 1×1015 protons cm?2. FTIR spectra of proton (3 MeV) irradiated Makrofol‐N showed a strong decrease of almost all absorption bands at about 1× 1014 protons cm?2. However, beyond a higher critical dose an increase in intensity of almost all characteristic bands was noticed. The appearance of a new peak at 3,500 cm?1 (‐OH groups) was observed at the higher fluences in the FTIR spectra of proton‐irradiated polycarbonate. XRD measurements showed an increase of full width at half maximum (FWHM) and the average intermolecular spacing of the main peak, which may be due to the increase of chain scission and the introduction of ‐OH groups in the proton irradiated polycarbonate. 相似文献
19.
W. Wardzyński H. Szymczak M.T. Borowiec K. Pataj T. Łukasiewicz J. Żmija 《Journal of Physics and Chemistry of Solids》1985,46(10):1117-1129
The optical absorption and ESR spectra of Bi12GeO20 and B12SiO20 doped with Mn have been measured before and after illumination with visible light. Uniaxial stress measurements on a sharp line observed at 8026 cm?1 were performed. The observed ESR spectrum is a superposition of six lines resulting from the hyperfine interaction of manganese ions in tetrahedral positions. The g-factor and hyperfine constant are g = 1.999 ± 0.003 and A = 78 Gs. Analysis of the light-induced absorption spectrum leads to the conclusion that a small hole polaron bound to an Mn impurity at a tetrahedral site is responsible for the very broad absorption band which appears after illumination. The sharp line is interpreted as due to a transition inside the Mn+ center in tetrahedral coordination. Bands in the region 10,000–16,000 cm?1 are due to Mn3+ centers in interstitial positions, whose symmetry can be treated to a first approximation as tetragonal. The following crystal field parameters for this center were found: B = 565 cm?1, Dq = 1400 cm?1, Dt = ?330 cm?1, Ds = 4170 cm?1 and C = 2260 cm?1. The illumination conditions which are needed for homogeneous coloration of the sample are also discussed. 相似文献
20.
Abstract Mn+ ions in off-centre position along [100] have been produced in BaF2:Mn by X-irradiation at LNT. Their EPR spectra are characterized by g-2. 0107. D = 265.8·10?4cm?1. A = 122.9·10?4cm?11 and a superhyperfine structure arising from 8 surrounding F? nuclei. In the optical absorption spectrum they show up by a band at 411 nm. This behaviour is compared with the results found for SrF2:Mn. After X-irradiation at room temperature beside a different Mn+ centre two species of Mn0 appear in non-cubic position. Both interact dominantly with two F? neighbours. Possible models for these species are discussed. 相似文献