Analysis of torsional vibrations of an ethane molecule

Based on the solution for the Mathieu equation, we obtained wave functions for the internal rotation of an ethane molecule that satisfy the symmetry properties of the group G₃₆. We calculated the frequency of the principal torsional transition (273 cm⁻¹). The types of symmetry of the energy levels and transition probabilities in IR and Raman spectra are determined. We note drawbacks of divisible permutable-inverse nuclear groups and the groups of molecular symmetry associated with their construction, as well as difficulties that appear when equivalent rotations are used. The possibility of avoiding the application of an extended group is indicated. Belarusian State University, 4, F. Skorina Ave., Minsk, 220050, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 26–31, January–February, 1997.     

Vibrational spectrum of RbVOPO4

The infrared and Raman laser spectra of RbVOPO₄ were recorded and briefly discussed with the aid of factor group analysis. Some comparisons with the spectra of related materials were also made.     

Effect of Strong Irradiation on Raman Magnetic Resonance in an AX Spin System

In Raman magnetic resonance an initially prepared multiple quantum coherence (MQC) in a spin system introduces all the possible single quantum (SQ) and multiple quantum (MQ) NMR signals when an irradiation is applied during the detection period. If the irradiation is weak, the induced signals include those MQs up to the very order of this given MQC, while in the strong irradiation case, those MQs beyond the very order of the given MQC will also appear. An analytical approach based on the product formalism is developed to predict the intensities and frequencies of these induced signals. The analysis provides a complete treatment to cover both cases of weak and strong irradiation. It is also demonstrated with an AX spin system. Experimental results are in qualitative agreement with the analysis.     

The disorder-longitudinal acoustic mode of oligo (ethylene glycol)-lithium trifluoromethane sulfonate solutions as studied by FT Raman spectroscopy

This work presents the results of Fourier transform Raman spectroscopy investigations of the disorder-longitudinal acoustic mode (D-LAM) of oligo(ethylene glycol) dimethyl ether-lithium trifluoromethane sulfonate solutions in dependence on oligomer chain length, temperature and salt concentration. The peak position and the bandwidth of this mode depend on the long-range conformational disorder of oligo(ethylene glycol) chains. The addition of salt causes a marked increase of the long-range conformational disorder. The frequency shift of the D-LAM combined with changes in the asymmetric CH₂ stretching bands indicate that the increasing long-range conformational disorder is connected with an increasing short-range conformational disorder of oligomer chains in a linear relationship.     

GaAs-InP异质材料的结构特性和光学特性研究

我们在低压金属有机汽相沉积(MOCVD)设备上采用两步升温法与金属有机源流量周期调制生长界面过渡层方法制备出GaAs-InP材料,并对此进行了X-射线衍射、低温光致发光谱(PL)和Raman谱分析,结果表明,GaAs外延层的位错密度低于用两步升温法得到的GaAs材料,PL谱峰较强,GaAs的特征激子峰和杂质相关的激子峰同时被测到。Raman谱PL谱的峰移表明GaAs外延层处于(100)双轴伸张应力下,应力大小随温度变化是由于GaAs、InP之间的热膨胀系数不同。     

界面有序单分子层膜结构的红外和拉曼光谱表征

本文综述了近十几年来红外和拉曼光谱方法用于表征空气／水界面单分子层（Ｌａｎｇｍｉｕｒ膜）、油／水界面和空气／固界面单分子层（ＬＢ膜）分子结构的最新进展。     

XeCl激光泵浦高压氢的衍射极限SRS斯托克斯光输出

利用XeCl准分子激光在高压氢中产生受激喇曼散射获得峰值功率为0.2MW、衍射极限发射角的一阶(353nm)斯托克斯输出,井研究了泵浦激光发散角对受激喇曼散射转换效率的影响.     

氮化铝结构的高温Raman光谱分析

本文测量了氮化铝在不同温度下的Raman光谱 ,并确定了氮化铝的光学声子模E2 1、A1(TO)、E2 2 、E1(TO)、A1(LO)和E1(LO)Raman散射峰的频率 ,它们分别为 2 5 2cm- 1、6 1 4cm- 1、6 5 8cm- 1、6 72cm- 1、894cm- 1和 91 2cm- 1,其中光学声子模A1(TO)、E2 2 的Raman散射峰比较明显。随着温度的升高 ,A1(TO)、E2 2 散射峰的频率向低波数方向变化 ,表明氮化铝粉末压制体中存在的压应力逐渐减小 ;这两个散射峰的半高宽逐渐增大 ,说明随着温度的升高 ,存在氮原子和铝原子的扩散使得氮化铝粉末压制体中晶体结构逐渐发生变化。由于氮化铝粉末本身在空气中易与水蒸气发生反应 ,生成的Al(OH) 3 或AlOOH在加热过程会发生分解 ,干扰样品高温Raman光谱测量。     

Raman spectra and XPS studies of phase changes in Ge2Sb2Te5 films

Ge_2Sb_2Te_5 film was deposited by RF magnetron sputtering on Si (100) substrate. The structure of amorphous and crystalline Ge_2Sb_2Te_5 thin films was investigated using XRD, Raman spectra and XPS. XRD measurements revealed the existence of two different crystalline phases, which has a FCC structure and a hexagonal structure, respectively. The broad peak in the Raman spectra of amorphous Ge_2Sb_2Te_5 film is due to the amorphous －Te－-Te－ stretching. As the annealing temperature increases, the broad peak separates into two peaks, which indicates that the heteropolar bond in GeTe_4 and the Sb－Sb bond are connected with four Te atoms, and other units such as (TeSb) Sb－Sb (Te_2) and (Sb_2) Sb－Sb (Te_2), where some of the four Te atoms in the above formula are replaced by Sb atoms, remain in crystalline Ge_2Sb_2Te_5 thin film. And from the results of Raman spectra and XPS, higher the annealing temperature, more Te atoms bond to Ge atoms and more Sb atoms substitute Te in (Te_2) Sb－Sb (Te_2).