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1.
H center in CsBr is studied and found to have two σ-polarized optical absorption bands at 437 and 490 nm and one π-polarized band at 1062 nm. Oscillator strengths of these three bands are found to be in the ratio of 1:0.2:0.003. 相似文献
2.
Reflectivity spectra of CuInSe2, CuInTe2 and CuGaTe2 are measured in the photon energy range from 2 to 9 eV. All compounds exhibit nearly the same reflectivity structures, and a comparison with measurements on the other Cu-III-VI2 semiconductors shows that the band structures of all Cu-III-VI2 compounds should be very similar except the energy range near the fundamental edge. 相似文献
3.
Calculated dispersion curves and frequency spectra are presented for CsCl, CsBr and CsI. These calculations have been made using the deformation dipole model including both first and second neighbor non-coulomb forces. The best fit to the experimental results is provided by a simple five parameter first neighbor model. 相似文献
4.
Ground and excited states of three exciton series are observed in the region of fundamental absorption edge of AgAsS2 crystals. The contours of exciton reflection spectra are calculated and the main parameters of excitons and energy bands are determined in the center of Brillouin zone. The optical reflection spectra are investigated at 30 K in E∥c and E⊥c polarizations in AgAsS2 crystals in the region of 2-6 eV. The optical functions are calculated from the reflection spectra and a scheme of electronic transitions responsible for peculiarities of reflection spectra deep into the absorption band is proposed. 相似文献
5.
HeI and Mg Kα1,2 valence band photoelectron spectra of polycrystalline samples of NbO2, MoO2 and RuO2 are reported. A marked increase is observed in the intensity of the metal 4d structure, relative to that due to oxygen 2p electrons, on changing from X-ray to UV excitation. The superior resolution of the 4d signals in the HeI spectra reveals the presence of the Fermi edge in the metallic oxides MoO2 and RuO2. In addition, the HeI spectrum of MoO2 shows a splitting of the metal 4d signal, confirming established ideas concerning the electronic structure of such materials. 相似文献
6.
Richard J. Colton J.Wayne Rabalais 《Journal of Electron Spectroscopy and Related Phenomena》1974,3(5):345-357
Photoelectron and electronic absorption spectra of SCl2, S2Cl2, S2Br2, and (CH3)2S2 have been measured and analyzed. Quantum chemical calculations (CNDO/ 2 and MWH (Mulliken-Wolfsberg-Helmholtz) have been carried out and the electronic structures have been described in terms of molecular orbital theory. The variation in differential photoionization cross-section as a function of incident photon energy and results of MO computations are used to identify ionization bands and assign ground state MO configurations. Suggested ground state electronic structures coupled with computed virtual MO's are used to interpret the visible and near-ultraviolet electronic absorption spectra. The low energy excited states are described as molecular states followed by the initial members of Rydberg series. Calculated oscillator strengths for molecular transitions are in good agreement with those observed experimentally. Quantum defects, δ, for the Rydberg states have been calculated from the Rydberg equation using the adiabatic first ionization potential. 相似文献
7.
Electron energy loss spectra of CO, N2 and O2 have been recorded in the regions of carbon, nitrogen and oxygen K-shell excitation and ionisation. These results are compared to previous energy loss, photoabsorption and theoretical studies of the same spectral regions. Several inconsistencies in the published spectra are clarified in the present work. Comparisons with recent calculations of the K-shell continua of these molecules are presented. Vibrational structure in the K → π * transitions of CO (C 1s) and N2 (N 1s) has been resolved in high-resolution studies (< 0.1 eV FWHM) of these species. 相似文献
8.
The diatomic molecules, PtO and Pt2, as well as atomic Pt, were isolated in Ar and Kr matrices at a temperature of ca.12K. The absorption spectra of these species were photographed in the wavelength region 2500–9000 Å. Probably three systems of PtO were observed but none of them seemed to correspond to the earlier analyzed intense systems of gaseous PtO having a 1Σ state, designated X1Σ, as their common lower state. The assumption that this state should be the ground state of PtO is thus rather uncertain. A single progression of sharp bands in the near-infrared spectrum was ascribed to the dimer Pt2. In addition, some absorption lines due to Pt atoms were found in the ultraviolet region. 相似文献
9.
S.V.J. Lakshman S. Buddhudu 《Journal of Quantitative Spectroscopy & Radiative Transfer》1982,27(5):531-540
The values of Slater-Condon, spin-orbit, Racah, and Judd-Ofelt intensity parameters are reported. Observed energy levels and spectral intensities have been correlated with theoretically computed values. The nature of bonding in Nd3+ complexes is discussed. The oscillator strength of the hypersensitive transition decreases with a decrease of the Judd-Ofelt T2 parameter. 相似文献
10.
Raman spectra of the orthorhombic (II) and high pressure (III) phases of titanium dioxide at pressures to 372 kbar and effects of temperature and hydrostatic pressure on Raman spectra of the tetagonal cassiterite-like phases of TiO2, GeO2 and SnO2 are described. At room temperature, the TiO2 II–III transition is sluggish, and metastable coexistence was observed from 200 to 300 kbar. The Raman spectra of TiO2-III imply that its primitive cell contains at least four formula units; however, the structure could not be established from the Raman spectra and available powder X-ray diffraction patterns.The temperature and pressure dependences of the spectrum of the tetragonal MO2 phases together with bulk moduli and thermal expansion data were used to evaluate the pure-volume and pure-temperature contributions to the isobaric temperature dependence of the Raman frequencies. Large anharmonicities in TiO2 are attributed to hybridization of the oxygen p states with the d states of the Ti ion. GeO2, where p-electron bonding is involved, is much less Enharmonic. 相似文献
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12.
The phonon spectra of metallic disilicides VSi2, NbSi2, and TaSi2 have been studied in detail by inelastic neutron scattering at 300 K and specific heat measurements between 10 K and 250 K. The specific heat calculated from the generalised phonon density of states extracted from neutron measurements is in good agreement with the measured lattice contribution to the specific heat. The properties of the phonon spectra are discussed in relation with other data reported for these isostructural and isoelectronic disilicides. 相似文献
13.
V. Riede H. Sobotta H. Neumann Hoang Xuan Nguyen W. Möller G. Kühn 《Solid State Communications》1978,28(6):449-454
The lattice vibration spectra of CuInSe2 and CuGaTe2 were investigated by infrared reflectivity measurements in the wavenumber range from 55 to 5000 cm?1. The mode energies were determined by a Kramers-Kronig analysis of the spectra. The results are compared with existing measurements and some general trends in the phonon energies of the I-III-VI2 compounds are discussed. 相似文献
14.
The Raman spectra of single crystals of CrO2 and MoO2 have been studied from 77°K to 500°K for a comparison with the heavily damped phonon features in metallic VO2. The spectrum of MoO2 is very similar to that of monoclinic VO2 whereas CrO2 exhibits phonon spectra similar to rutile with no appreciable change at the ferromagnetic c curie temperature. The results are discussed with respect to the various models proposed for the semiconductor-to-metal transition in VO2. 相似文献
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16.
The optical properties of graded chiral sculptured TiO2 thin films in axial and non-axial excited states are calculated using the rigorous coupled wave analysis method (RCWA) in conjunction with the Bruggeman homogenization formalism. The filtering frequency and polarization selectivity of these graded nanostructured TiO2 sculptured thin films showed dependence on both structural and deposition parameters. The results achieved are consistent with the experimental data [K. M. Krause and M. J. Bret, Adv. Funct. Mater. 18 (2008) 3111]. 相似文献
17.
Hitoshi Yoshino Kazuo Shimokoshi Eizo Miyazaki 《Journal of Electron Spectroscopy and Related Phenomena》1985,36(3):269-279
DV-Xα calculations have been applied to various small clusters of rutile-family dioxides (NbO2, MoO2 RuO2). It appears that by taking into consideration the potential due to the atomic charges, the density, the ionization cross sections of the energy levels, and by summing the density of states (DOS) of the two different clusters representing surface structures, computations on even small clusters provide information which compares well with the experimental XPS spectra. 相似文献
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19.
The first-order Raman spectra of FeS2, MnS2 and SiP2 are measured at room temperature. The frequencies of all Raman-active phonons are obtained. We describe the displacement patterns and discuss the extent to which the concept of a molecular crystal can be applied. 相似文献
20.
Visible optical properties of two crystalline fibers (KY3F10 and LiLuF4) doped with Dy3+ have been investigated. In particular, the room-temperature absorption spectra have been analyzed using the Judd–Ofelt theory and the intensity parameters have been obtained. A criterion suitable for determining the proper choice of the dopant composition to tailor the luminescence properties of the crystals is proposed. 相似文献