Computer checking of rotational line intensity factors for diatomic transitions

Previously published analytical formulae for the rotational line intensity factors of diatomic molecules have been compared with results from a comprehensive computer program, which determines numerical intensity factors for both spin-allowed and spin-forbidden electric and magnetic dipole transitions in diatomic molecules. The comparison uncovered several typographical errors and a few algebraic errors in the published formulae. The changes required in the formulae to give agreement with the results from the computer program are tabulated.     

测定汞原子塞曼谱线相对强度

在原塞曼效应实验基础上，测定了塞曼分裂各谱线的相对强度，以作为原实验的补充．     

A current operator for the rotational model

A current operator for the rotational model is given. This operator is then used to calculate experimentally observable transition current multipoles.     

Choice of the informative parts of the rotational raman spectrum when measuring gas temperatures in the range 300–1200°K

The question of choosing the most informative parts of the rotational Raman spectrum for purposes of temperature measurements is considered, and to this end relationships for calculating the theoretical accuracy of temperature determination are derived. The results of some practical calculations relating to the measurements of air temperature at 300–1200°K are presented.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 116–119, January, 1977.     

水声波导中包络线谱强度数值预报

为了预报声呐远距离检测包络线谱的性能,本文分析在辐射噪声传播过程中包络线谱强度衰减的原因及提出在水声波导中包络线谱强度的数值预报方法。依据周期性局部平稳过程对舰船辐射噪声建模,推导出无噪声干扰及有噪声干扰下的包络线谱强度的数学表达式,获得了包络线谱强度传播衰减的规律,在水声波导中包络线谱声级传播规律与平稳谱一致,但包络线谱高出连续谱的强度的衰减取决于随信噪比变化的调幅深度修正因子。包络线谱强度数值预报方法如下:先利用传播衰减的数值方法例如用简正波方法波数积分方法PE方法等求出平稳辐射噪声的传播衰减,再求信噪比,最后依据调幅深度修正因子获得包络线谱强度降低的分贝数,预报出在水声波导中任意一点包络线谱信号高度。该理论和数值预报方法具有创新性,实用,简单,适合工程应用。     

汞原子塞曼效应分裂谱线相对强度的测量

为了研究塞曼效应分裂谱线的相对强度,分析了Hg(546.1 nm)谱线能级在外磁场中的分裂情况,详细给出了分裂能级的量子数分布和理论相对强度;在此基础上采用CCD拍摄了分裂谱线干涉圆环的图像,并对其进行了强度分析,通过图像强度处理得到各分裂谱线相对强度与理论分析结果十分接近;表明采用CCD图像技术能较好的分析塞曼效应现象和规律.     

Anomalies in the polarized raman spectrum of crystal quartz

Summary By means of coherent Raman scattering we have measured in quartz the dispersion of the elements of the Raman tensor in the range (900÷1070) cm⁻¹. The results determine with good accuracy the relative contribution of the various modes to the second-order nonlinear susceptibility. For some elements of the Raman tensor the present results greatly improve the precision of data already known; for others the dispersion and the relative strengths have been measured for the first time. In particular, a strong, frequency-dependent, asymmetry of the Raman tensor has been evidentiated; this asymmetry is interpreted in terms of optical Raman activity.     

Calculation of torsional and rotational raman spectra of hydrogen peroxide

We present calculated intensity distributions in torsional, rotational, and torsional-rotational Raman lines in spectra of hydrogen peroxide. Ab initio calculations of polarizability tensor components as functions of internal rotation angle were carried out in the HF/6-311G approximation. It is shown that the structure and transformational properties of the polarizability tensor components of hydrogen peroxide in extended molecular symmetry group G₄(EM) permit formation of purely rotational and torsional and rotational-torsional Raman spectra. Common expressions to calculate Raman line intensities governed by torsional and rotational motions of the non-rigid symmetric top molecule are obtained. The torsional components of the line intensities have been calculated by estimating the appropriate matrix elements. The contribution of rotational components has been calculated using the 3j-symbols technique.     

The rotational spectrum of silacyclohexane

The rotational spectra of the normal and Si-d₂ isotopomers of the chair form of silacyclohexane have been measured by microwave absorption spectroscopy. A partial r₀ structure has been obtained. The rotational spectra of some, the most intense, vibrational satellites have also been measured. They belong to the ring-puckering motions. Their vibrational energies and their shifts of planar moments of inertia with respect to the ground state indicate that the amplitude of these vibrations is larger than in cyclohexane. The dipole moment has also been determined: μ_a = 0.75(2), μ_c = 0.280(2), and μ_tot = 0.80(2) D.     

The rotational spectrum of trichlorofluoromethane

The microwave and millimetre-wave spectra of CF³⁵Cl₃ have been measured in the ground and first excited doubly degenerate (E) vibrational states. Rotational, centrifugal distortion, and quadrupole parameters were obtained for both states. In the E state, strong l-resonance was observed, enabling some rotation-vibration parameters to be accurately determined. In addition, there was a splitting of the (kl − 1) = ± 1 lines due to the asymmetry of the individual quadrupole coupling tensors with respect to the principal inertial axes.     

Intensity of the sulfur dioxide rotational spectrum

The integral band intensity of the pure rotational absorption of SO₂ gas has been determined from far-i.r. spectra. From the curve of growth, the value at 298°K is found to be S^o_b = 35.2±1.5atm^-1 -cm^-2. The entire set of experimental data has been analyzed using an absorption band model. The derived intensity agrees with that obtained from the curve of growth to be better than 10%. This result should be of value in connection with atmospheric models of the planet Venus.     

Temperature dependence of raman line width for a molecular crystal

Nondiagonal elements in the polarization operator explain the anomalous widths of some Raman lines arising at external and internal vibrations of a molecular crystal. Thermal expansion affects the widths of some lines. The treatment is in agreement with the available experimental evidence.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, Vol. 12, No. 1, pp. 37–41, January, 1969.     

A rotational model description of F

Rotational-particle coupling (RPC) model calculations have been performed for the positive parity states of ¹⁹F using a deformed oscillator potential (Nilsson) and a deformed Woods-Saxon potential. The energy spectra and spectroscopic factors (for the ¹⁸O(³He, d)¹⁹F reaction) are very similar for both calculations and in good agreement with experimental values and with recent full intermediate coupling shell-model calculations.     

A line list of allowed and forbidden rotational transition intensities for water

Pure rotational lines are important for monitoring water concentrations in many environments both in space and on earth. A list of line intensities of rotational transitions for H₂¹⁶O is calculated using variational nuclear-motion wave functions and an ab initio dipole moment surface. This methodology should be equally reliable for both allowed and forbidden rotational transitions. Extensive comparisons are made with available intensity data for these transitions including the HITRAN and JPL databases. Problems are identified with some of these data. A list of 555 allowed and 846 forbidden rotational transition lines within the ground vibrational state is made available.     

The millimeter-wave rotational spectrum of fluorobenzene

The room-temperature rotational spectrum of fluorobenzene was studied in the frequency region 167-318 GHz. Rotational transitions were assigned and measured in the ground vibrational state, and all six excited vibrational states with energies below 600 cm⁻¹, i.e., v₁₁ = 1, v₁₁ = 2, v_18b = 1, v_16a = 1, v_16b = 1, and v_6a = 1. Accurate quartic-level spectroscopic constants were determined for all states, allowing spectral predictions well into the submillimeter region. The states v_18b = 1 and v_16a = 1 were found to be connected by a strong Coriolis interaction, which allowed precise determination of their energy separation, ΔE = 7.455088(3) cm⁻¹. Unambiguous assignment of vibrational modes was made on the basis of the calculated inertial defect and nuclear spin statistical weights. Rotational constants for the ¹³C₄ isotopomer have also been redetermined and two new least-squares determinations of the geometry of fluorobenzene, r₀ and are reported.