Raman spectra of crystalline double sulphates

Raman spectra of single crystals of K₂M(SO₄)₂ · 6 H₂O where M=Mg, Zn, Ni or Co have been recorded for the first time usingλ 2537 as the exciting radiation. The corresponding five single sulphates have also been studied. Interesting results concerning the substitution of magnesium, zinc, nickel or cobalt in the double sulphate lattice on the sulphate frequencies are observed. The lattice spectra of these double sulphates are analysed group theoretically and discussed in relation to the lattice spectra of the corresponding individual sulphates. Certain new results concerning the Raman spectra of the individual sulphates have also been obtained and in the case of CoSO₄ · 7 H₂O the spectrum has been recorded for the first time.     

Raman spectra of crystalline iron perchlorate hexahydrate

Raman studies of crystalline iron perchlorate hexahydrate (Fe(ClO₄)₂·6H₂O) in the region of lattice and anion internal modes were carried out in the temperature range 80–385 K. The temperature‐dependent Raman results are consistent with those from previous works, showing that two phase transitions occur around 336 and 245 K. The transition at 336 K may be considered as an order–disorder transformation, while the one at 245 K is associated with the configurational disorder of the tetrahedron of the perchlorate ions. Copyright © 2008 John Wiley & Sons, Ltd.     

Raman spectra and thermal disordering of the crystalline structure of benzene

Disordering of rotational degrees of freedom of molecules in a benzene crystal is investigated from Raman spectra. Nonuniform smearing of the spectrum of librational vibrations to the wing of the Rayleigh line is established. The changes observed are interpreted on the basis of calculations of frequencies, intensities, vibration modes, and barriers to molecular reorientations in the crystal by the method of atom-atom potentials. The line broadening in the spectrum of external vibrations by reorientations of molecules in the crystal as a function of their mode is analyzed. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 3, pp. 394–400, May–June, 1999.     

Relative intensities in x-ray photoelectron spectra. Part II

Experimental data on the relative intensities of X-ray photoelectron lines of some elements with 22 ? Z ? 56, and the calculations for the photoionization cross-sections for inner levels of some elements with 21 ? Z ? 63 are reported. The relationship between photoionization relative cross-sections and line relative intensities is examined. Theoretical values of the photoionization cross-sections were used in the calculations of relative intensities of molecular valence levels for AO₄^x? (A = Cl, S, P, Se, As), AF₆^x? (A = S, Si, Al), COS, CS₂ and H₂S.     

Isotope effects in Raman spectra of crystalline sulfur α-S8

The Raman spectra of ³²S, ³³S, and ³⁴S powders, as well as ^naturS powder with the natural isotopic composition, have been measured in the temperature range of 5–300 K. The isotope mass dependences of the vibrational frequencies have been obtained. It has been shown that such a dependence in the region of mixed translational-librational modes differs from the dependences known for monatomic inorganic crystals. The role of zero-point vibrations for low- and high-frequency modes has been revealed throughout the entire temperature range.     

Raman and IR spectra of crystalline phosphine in the γ phase

The γ phase of crystalline phosphine has been studied using IR and Raman spectroscopy. The observations include both pure phases, PH₃ and PD₃, and many of the modes of PH₃, PH₂D and PHD₂ dilute in PD₃ as well as of PD₃, PD₂H and PDH₃ dilute in PH₃. The phase transition β → γ is very slow for PH₃, but much more rapid for PD₃.Evidence is adduced pointing to the existence of inequivalent sites in this crystal, but none of a number of suggested models for the unit cell is entirely consistent with the numbers of multiplet components of the internal modes, nor with the numbers of external (lattice) modes observed in the IR and Raman.     

Isotope effects in Raman spectra of crystalline alkali-metal chlorates and bromates

Halogen and oxygen atom isotope effects have been observed in Raman spectra of single crystal NaClO₃, KClO₃, NaBrO₃, and KBrO₃. Orientational splitting of ³⁵Cl¹⁶O₂¹⁸O^? and ³⁷Cl¹⁶O₂¹⁸O^? ion vibrational modes was observed in KClO₃. Splitting of the v₁ mode of ⁷⁹Br and ⁸¹Br isotopes of singly substituted ¹⁷O and ¹⁸O bromate ions in NaBrO₃ and KBrO₃ is on the order of 1.5 cm^?1 in agreement with a calculation of isotopic frequencies. However, the predicted splitting between v₁ of the major isotopes, ⁷⁹Br¹⁶O₃^? and ⁸¹Br¹⁶O₃^?, was not observed, and the results of a band contour analysis suggest that a single k = 0 phonon is derived from the totally symmetric stretching mode of both species.     

分子束外延PbTe单晶薄膜的反常拉曼光谱研究

采用分子束外延(MBE)方法在BaF₂(111)衬底上生长了高质量的PbTe单晶薄膜， 拉曼光谱测量观察到了表面氧化物的振动模、布里渊区中心(q≈0)纵光学(LO)声子振动模以 及声子-等离子激元耦合模振动.随着显微拉曼光谱仪激光光斑聚焦深度的改变，各拉曼散射 峰的峰位、积分强度、半高宽等都表现出不同的变化趋势. 随着激光光斑聚焦位置从样品表 面上方3μm处变化到表面下方3μm处，PbTe外延薄膜的LO声子频率从119cm^-1移 动到124cm^{-1关键词： PbTe外延薄膜 拉曼散射 纵光学声子}     

The effects of microcrystal size and shape on the one phonon Raman spectra of crystalline semiconductors

Small physical dimensions of the scattering crystals lead to a downshift and broadening of the first order Raman line through a relaxation of the q = 0 selection rule. We consider the effect of the exact shape of the microcrystal and show that there are significant differences between spherical, columnar and thin slab microcrystals. The relationship between the width, shift and asymmetry of the Raman line is calculated and is in good agreement with available experimental data.     

Raman spectra of fosterite

The normal modes of the Raman-active phonons in the center of the Brillouin zone in a natural monocrystal of Mg₂SiO₄ were measured by using Raman scattering. All of the modes predicted by group theory were observed and measured. Some deviations from previously published values in synthetic samples were observed for the low energy phonons.     

Raman spectra of carbyne-fullerene structures

Carbon films grown based on sintering of carbon nanoclusters 1–3 nm in size are studied by the Raman scattering (RS) method. A comparison of RS spectra of fullerene, β-carbyne, diamond, and obtained carbon films allowed the assumption that the film structure corresponds to “carbyne-fullerenes” whose existence was theoretically predicted in [14–16].     

Raman spectra of amorphous SiC

It has been found that the condition of the sample preparation exerts large influence on the structural disorder of the films. For the sample prepared by sputtering method, the dependence of CC band on substrate temperature T_s and partial pressure of SiH₄ during the sputtering has been measured.     

Raman spectra of silicon monoxide

The stoichiometric thin films of SiO have been studied by Raman scattering. The spectra indicate three main peaks at 444 cm⁻¹, 454 cm⁻¹ and 502 cm⁻¹ which may correspond to an atomic arrangement of tetrahedra of the type SiSi_yO_4−y where y ≠ 0 and y ≠ 1. The results contradict the mixture model (Si+SiO₂) and show that the SiO oxide cannot be considered as a mixture of Si and SiO₂.     

近代Raman光谱技术

介绍几种近代拉曼（Raman）光谱技术及其在科学中的应用。