An experimental study and computation of the infrared absorption spectrum of 3,5-dimethyl-4-phenylpyridine

The infrared absorption spectrum of 3,5-dimethyl-4-phenylpyridine in the 400–2000 cm^–1 range was obtained. A valence-force model was used to compute the fundamental frequencies and normal vibrational modes. The experimental and computed data were found to be in good agreement. The addition of two methyl groups in the 3,5-positions of the-phenylpyridine molecule reduces conjugation between the benzene and pyridine rings, rendering the molecule noncoplanar. The free rotation of the methyl groups about the C-C bond is retarded by the free electron pair in the nitrogen atom of the pyridine ring.     

The infrared absorption spectrum of γ-phenylpyridine

The infrared absorption spectrum of-phenylpyridine has been recorded experimentally in the range 600–2000 cm^–1 and the fundamental frequencies and forms of the normal vibrations have been calculated using the valence force field. The experimental and calculated data show satisfactory agreement.In conclusion the authors wish to thank L. A. Gribov for assistance and discussion of the results.     

Calculation and investigation of infrared absorption spectrum of rhodanine

The IR absorption spectrum of rhodanine was obtained in the 400–3500 cm^–1 region. A full set of frequencies for the vibrational spectrum was determined by a mechanical model with C_s symmetry, and an interpretation of the bands in the IR spectrum of rhodanine is given. The change in the IR spectrum of cyclopentane when the structure of the ring is complicated by introduction of two heteroatoms is examined. It is shown that a sulfur atom reduces and a nitrogen atom increases the frequencies of the ring stretching vibrations. Successive increase in the number of heteroatoms in the cyclopentane ring lowers the D_5h symmetry of the molecule, but traces of high symmetry remain in the spectrum of rhodanine.     

Calculation and study of the IR absorption spectrum of hydantoin

The IR absorption spectrum of hydantoin has been obtained in the range 400–3500 cm^–1, and the normal-vibration frequencies are calculated on the basis of the mechanical model. The spectrum is interpreted.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol. 12, No. 6, pp. 116–120, June, 1969.     

Measurement and analysis of the infrared absorption spectrum of the 2ν2 band of 12CH4

Approximately 500 infrared absorption lines with room-temperature strengths between 3 × 10^?5 and 1 × 10^?2 atm^?1 were assigned to the 2ν₂ band of ¹²CH₄ in the region from 2930 to 3250 cm^?1. These determine 207 of the 212 upper-state energy levels through J′ = 12 as well as a number of levels with J′ = 13 and 14. All but 17 of the levels with J′ ≤ 12 are calculated to 0.03 cm^?1 or better on the basis of a Hamiltonion that contains Coriolis and Fermi interaction terms coupling the upper states of the five bands, 2ν₄, ν₂ + ν₄, ν₁, ν₃, and 2ν₂.     

Measurement and analysis of the far infrared absorption spectrum of the gaseous mixture H2-CH4

The collision-induced absorption of H₂-CH₄ mixtures was measured from ∼20 to 900 cm^-1 at 195 and 297 K. By subtracting the absorption due to H₂-H₂ and CH₄-CH₄ collisions from that of the mixture, the absorption due to H₂-CH₄ collisions was obtained. This spectrum was analyzed using the BC model line shape to provide a way of estimating the far-i.r. spectrum of H₂-CH₄ for various concentrations of H₂ and CH₄. Theoretical spectral moments were computed with different potential functions and compared with experimental values.     

Calculation and study of the ir absorption spectrum of 2,4-thiazolidinedione

The IR absorption spectrum is found for 2,4-thiazolidinedione in the range 400–3500 cm^–1, and the normal modes are calculated on the basis of a model for this molecule. The spectrum is interpreted.Translated from Izvestiya VUZ. Fizika, No. 12, pp. 64–68, December, 1969.     

反常吸收与高质量的远红外光谱

在水汽含量恒定但相对湿度较大的情况下,远红外光谱仪得不到理想的100%线。这表明过高的水汽含量将会导致反常吸收现象。反常吸收的出现将严重影响远红外光谱的质量。研究了光谱仪内部空气相对湿度和光谱分辨率对反常吸收的影响,发现降低水汽含量和采用适当光谱分辨率可以有效抑制反常吸收现象,对获得高质量的远红外光谱很有益处。在无反常吸收现象发生的实验条件下,采用"湿度中和法"在空气湿度波动的情况下也可以得到理想的100%线,这为快速获得高质量的远红外光谱提供了新测量方法。     

Ab initio prediction of the infrared absorption spectrum of the C2Br radical

The first three electronic states of the C₂Br radical, correlating at linear geometries with ²Σ⁺ and ²Π states, have been studied ab initio, using Multi Reference Configuration Interaction techniques. The electronic ground state is found to have a bent equilibrium geometry, RCC=1.2621Å, R _CBr=1.7967Å, ∠ CCBr=156.1°, with a very low barrier to linearity. Similarly to the valence isoelectronic radicals C₂F and C₂Cl, this anomalous behaviour is attributed to a strong three-state non-adiabatic electronic interaction. The Σ ,Π_1/2,Π_3/2 vibronic energy levels and their absolute infrared absorption intensities at a temperature of 5 K have been calculated for the ¹² C¹² C⁷⁹Br isotopomer, to an upper limit of 2000 cm^?1, using ab initio diabatic potential energy and dipole moment surfaces and a recently developed variational method.     

The infrared absorption spectrum and the inversion degree of manganese ferrite

Infrared spectra of MnFe₂O₄ with inversion degrees of 0.05 and 0.2 are reported. It can be concluded that the absorption observed at 335 cm^?1 has to be the third fundamental IR active mode.     

氮化铝薄膜的红外吸收光谱和喇曼光谱的研究

本文报道用直流平面磁控溅射法在Si片上生长c轴高度择优取向AIN薄膜的光学特性.俄歇谱分析表明薄膜是高纯的.从红外吸收光谱上分析获得晶格振动纵、横模的频率分别为2.5×10~(13)HZ和1.8×10~(13)Hz.从喇曼光谱上分析获得AIN薄膜的光学声子频率为297、512、607、656、832cm~(-1).与几种已知的纤锌矿结构二元化合物的声子频率模式类比获得AIN的光学声子模式.进一步分析表明AIN是一种静电力大于原子间各向异性力的晶体,且声子的最高频率与r~(-3/2)N~(-1/2)成正比.     

Far-infrared absorption spectrum of the CH4-H2 gaseous mixture

The rototranslational absorption spectrum of the CH₄-H₂ gaseous mixture has been measured at five different temperatures from 296 to 140 K, in the frequency range 150–850 cm^-1. The absorption spectra due to the CH₄-H₂ interactions have been analyzed considering only the quadrupolar induction of H₂ on CH₄ and the octupolar and hexadecapolar inductions of CH₄ on H₂. Under this assumption, the experimental data have been well accounted for, thereby providing a reliable way of predicting the CH₄-H₂ spectrum in a wide temperature range.     

The near infrared cavity-enhanced absorption spectrum of methyl cyanide

The absorption spectrum of methyl cyanide (CH₃CN) has been measured in the near IR between 6000 and 8000 cm^?1 with a resolution of 0.12 cm^?1 using Fourier transform incoherent broadband cavity-enhanced absorption spectroscopy. The spectrum contains several weakly perturbed spectral regions; potential vibrational combination bands contributing to the spectrum are outlined. Line positions and cross-sections of CH₃CN between 6814 and 7067 cm^?1 have been measured at high-resolution of 0.001 cm^?1 using diode laser based off-axis cavity-enhanced absorption spectroscopy. A total of 4630 new absorption lines of CH₃CN are identified in this region. A value for the self-broadening coefficient has determined to be (3.3±0.2)×10^?3 cm^?1 mbar^?1 for one isolated line at 7034.171 cm^?1. Several line series have been identified in these regions and an autocorrelation analysis performed with a view to aiding future assignments of the rotational-vibrational transitions.     

Temperature dependence of the infrared absorption spectrum of antiferromagnetic semiconductor MnTe

The temperature dependence of the phonon absorption band of MnTe, 154 cm^?1, is investigated and an anomalously large shift is observed near the Néel temperature. The frequency variation due to the volume change and the magnetic terms are estimated, the latter fraction being not less than ca. 40%.     

On the absorption and reflection spectrum of amorphous selenium in the infrared region

The spectral' dependence of the reflectivity and the absorption coefficient of amorphous selenium in the region between 2 and 25 were exactly determined in this work on perfectly optically homogeneous samples. Differences in the infrared spectra compared with data from the literature are discussed. The refractive index in the long-wave region was calculated from the dispersion relation on the basis of the entire distribution known today of the absorption coefficient in a wave-length region from approximately 0·13 Å to 150 . The continuous component of the absorption in the long-wave region was found to be approximately proportional to the square of the wave-length. Finally, a theoretical deduction of the temperature dependence of the previously experimentally found wave numbers of absorption bands was shown.The author is grateful to Dr. H. Lundström from the research laboratories of the Bolidens Gruvaktiebolag Company, Skelleftehamn, Sweden, for valuable discussions and for his kind grant of a considerable amount of extremely pure selenium for this work. Thanks are also due to Ing. I. Srb for the preparation of optically homogeneous samples and Ing. S. Martínek for the graphical evaluation of the results.