首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Abstract

Vibrational spectra of 2,2′-pyridil and 2,2′-pyridil-18O in the solid state and in solutions have been measured in the Raman (4000–50 cm?1) and infrared (4000–100 cm?1). The assignment of the bands observed is performed using the group vibrational concept and isotopic shifts data of the normal modes. The presence of synand anti-phase vibrations of both pyridyl rings is discussed. The results are compared to the corresponding data for some similar molecules.  相似文献   

2.
Abstract

Vibrational spectra of 2-benzoyl pyridine and 2-benzoyl pyridine-18O have been recorded in the solid and molten state in the infrared (4000–100 cm?1) and in the Raman (4000–50 cm?1). Polarized Raman spectra in the molten state have also been measured. The assignment of the vibrational bands is performed using the group vibrational concept, isotopic shifts and polarization features of the normal modes.  相似文献   

3.
Abstract

Infrared and Raman spectra of 4-benzoylpiridine (4BP) and its 18O substituted derivative have been recorded in the solid and in the molten state. Polarized Raman spectra in the molten state have also been measured. The assignment of the vibrational bands is performed on the basis of isotopic shifts, group vibrational concept and polarization features of the normal modes. The previous assignment of the in- and out-of-plane deformations of the carbonyl group and the fundamentals below 700 cm?1 are questioned and corrected.  相似文献   

4.
Polarized Raman and IR spectra of a PbB4O7 single crystal were measured. The obtained spectra are discussed within the factor group approach for the orthorhombic P21nm(C2v7) space group with Z = 2 assuming that the crystal structure is built up of the (B4O7)2− framework and Pb2+ ions. It has been shown that vibrations of borate and Pb2+ units are observed above 240 and below 160 cm−1, respectively. The results obtained for the spontaneous Raman scattering have also been used in the discussion of the stimulated Raman spectra of the material studied—a new Raman‐laser crystal. The obtained results revealed that mainly translational motions of Pb2+ ions participate efficiently in the SRS effect. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

5.
Abstract

Vibrational spectra of 9-Fluorenone, 9-Fluorenone-18O and 9-Fluorenone-d8 have been recorded in the solid state and solutions in the infrared and (4000–100 cm?1) and in the Raman (4000–50 cm?1). Differential infrared linear dichroic spectra have also been measured. The assignment of the vibrational bands is performed using the group vibrational concept, isotopic shifts and polarization features of the normal modes.  相似文献   

6.
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.  相似文献   

7.
The IR spectra and polarized Raman spectra of crystals of hexahydrates of zinc potassium and ammonium sulfates have been obtained experimentally at 93 K and at room temperature. The frequencies and modes of normal vibrations of the octahedral complex [Zn(H2O)6]2+ have been calculated. The assignment of the observed lines of the internal and external vibrations of the crystal cell has been made by calculations and by factor-group analysis. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 2, pp. 162–168, March–April, 2000.  相似文献   

8.
The geometric parameters, the force field, and the absolute intensities of the IR and Raman spectra of acridone, the hydrogen-bonded dimer of acridone, and its N-deuterated analogue are calculated quantum mechanically in terms of the density functional theory by the B3LYP/6-31G(d) method. The vibrational bands in the IR and Raman spectra of acridone are assigned and interpreted using the calculational data on acridone dimers and the data on the isotopic shifts of vibrational frequencies upon deuteration. The vibrations of acridone and anthraquinone are comparatively analyzed. Original Russian Text ¢ K.V. Berezin, T.V. Krivokhizhina, V.V. Nechaev, 2006, published in Optika i Spektroskopiya, 2006, Vol. 100, No. 1, pp. 20–27.  相似文献   

9.
In this work, the Raman spectra of furan, furfuryl alcohol (FA), furfural, hydroxymethylfurfural (HMF), and levulinic acid were obtained in the 500 to 4000 cm−1 spectral region at room temperature. Vibrational wavenumbers were calculated for these compounds with the B3LYP method using the 6‐31 + G(2df,p) basis set. The experimentally determined CC and C C wavenumbers for furan and furan derivatives were in good agreement with the calculated wavenumbers without scaling factor, while the calculated CO and C H wavenumbers at ∼1660 and 3000 cm−1, respectively, showed larger deviations from the measured ones. The Raman spectra for furan and furan derivatives showed intense CC bands, whereas the levulinic acid spectrum showed intense C H vibrations with broad doublet CO bands. We also found that an empirical method based on the chemical structure similarities is able to predict the HMF Raman spectrum from the combined furfural and FA spectra. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

10.
α-Pyrazinamide and its α-Pyrazinamide-d2 as well as the 15N-isotopic derivative were synthesized with an isotopic content of 99.4% and their Raman and infrared spectra were recorded and assigned on the basis of isotopic shifts.  相似文献   

11.
The Raman and IR. spectra of solid diamminediiodidezinc (II) with 15N and 2H isotopic substitution have been measured. The spectra have been interpreted assuming C2v symmetry for the Zn(NH3)2I2 complex structure. The skeletal stretching metal-ligand modes vs(ZnN), vas(ZnN), vs(ZnI), vas(ZnI) as well as the three bending modes δ(NZnN), δ(IZnI) and δ(IZnN) were assigned by comparison with the spectra of Zn(NH3)2C12 and Zn(NH3)2Br2, and by the observed isotopic shifts of the frequencies. A normal coordinate analysis for the whole complex was carried out using the Local Symmetry Force Field Model.  相似文献   

12.
The infrared spectra of matrix-isolated sodium and potassium cyanides in neon, argon, krypton, and nitrogen matrices were examined over the range 4000 cm?1 to 33 cm?1. The effect of temperature cycling, which normally results in migration of trapped molecules to generate polymeric species, has been pursued. A careful study of the effect of superheating the vapor species on the spectra has also been carried out. By these means it has been possible to identify the bands in the spectrum due to monomeric and polymeric species. Isotopic frequency shifts were measured for a 13C-enriched sample of sodium cyanide and 13C- and 15N-enriched samples of potassium cyanide. From the measured isotopic shifts it was possible to determine the structure of these two compounds as being linear NaCN and KCN. Accurate force constants were calculated using the measured frequency values for the three fundamental vibrational modes of the different isotopic molecules of NaCN and KCN. Bands due to sodium and potassium cyanates were also identified in some of these systems. 13C and 15N isotopic frequency shifts were also observed for NaOCN and KOCN.  相似文献   

13.
Experimental Raman and FT‐IR spectra of solid‐state non‐deuterated and N‐deuterated samples of cyclo(L ‐Met‐L ‐Met) are reported and discussed. The Raman and FT‐IR results show characteristic amide I vibrations (Raman: 1649 cm−1, infrared: 1675 cm−1) for molecules exhibiting a cis amide conformation. A Raman band, assigned to the cis amide II vibrational mode, is observed at ∼1493 cm−1 but no IR band is observed in this region. Cyclo(L ‐Met‐L ‐Met) crystallises in the triclinic space group P1 with one molecule per unit cell. The overall shape of the diketopiperazine (DKP) ring displays a (slightly distorted) boat conformation. The crystal packing employs two strong hydrogen bonds, which traverse the entire crystal via translational repeats. B3‐LYP/cc‐pVDZ calculations of the structure of the molecule predict a boat conformation for the DKP ring, in agreement with the experimentally determined X‐ray structure. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

14.
The polarized Fourier-transform Raman spectra of oriented single crystals of K, Rb, and Tl hydrogen phthalates, as well as of deuterated potassium hydrogen phthalate, are studied in the range 50–3300 cm?1 in different scattering geometries. The frequencies of internal vibrations in the spectra of these compounds are assigned to vibrations of the orthophenylene and carboxyl groups. The replacement of K with Rb or Tl leads to an insignificant low-frequency shift of vibrations. A multiband structure of OH(D) stretching vibrations is observed in the range 1900–2800 cm?1 in the spectra of all hydrogen phthalates, which is caused by Fermi-resonance interactions. A number of additional bands are observed in the spectrum of deuterated potassium hydrogen phthalate, which indicates that deuterium atoms partially replace hydrogen atoms in both the orthophenylene and the carboxyl groups.  相似文献   

15.
The Raman and IR absorption spectra of single crystals of germanium isotopes 72Ge, 73Ge, 74Ge, and 76Ge in the region of phonon absorption and interband electronic transitions are studied at room temperature. The dependence of the Raman peak position on the atomic mass has the form ν ~ M–1/2. The shifts of the phonon absorption peaks of individual isotopes with respect to germanium of natural isotopic composition natGe are determined. With increasing average atomic mass of germanium, these peaks shift to longer wavelengths. In the region of interband electronic transitions, the intrinsic absorption edge of 76Ge is observed to shift by 1 meV to higher energies with respect to Ge of natural isotopic composition. For isotopes with atomic masses close to that of natural germanium (72Ge,73Ge, 74Ge), we found no significant difference in the band gap width at room temperature.  相似文献   

16.
The infrared and laser Raman spectra (100-4000 cm1) of benzocaine hydrochloride were recorded and its vibrations analysed. A theoretical spectrum with the AM1 semiempirical method was calculated. An infrared study with the temperature was also made. From the experimental data, the torsion and inversion barriers of amine group were calculated.  相似文献   

17.
IR and Raman spectra of (NH4)3ZnCl5 have been recorded. The observed spectra have been analysed on the basis of the vibrations of ZnCl 4 2− and NH 4 + ions. The appearance of multiple Raman bands indicates the presence of two different types of ammonium ions. The effect of anisotropic crystalline field over the ZnCl4 and NH4 tetrahedra is also discussed. The assignment of internal modes has been verified by the potential energy distribution calculations.  相似文献   

18.
The Raman intensities of counterion vibrations with respect to the phosphate groups of the double-helix backbone (ion-phosphate modes) in the low-frequency spectra (< 200 cm-1) of B -DNA with different alkali metal counterions have been calculated using the model for DNA conformational vibrations and the valence-optic approach. The results have showed that the spectra of DNA with heavy counterions ( Rb+ and Cs+ differ from the spectra of DNA with light counterions ( Na+ and K+ . The calculated spectra of DNA with heavy counterions are characterized by intensive modes of ion-phosphate vibrations that form one united band near 115cm-1. Ion-phosphate modes in the spectra of DNA with light counterions are characterized by higher frequencies (near 180cm-1) and much lower intensity. Our calculations explain why the modes of ion-phosphate vibrations are observed in Cs-DNA spectra rather than in Na-DNA. The determined sensitivity of the intensities of DNA low-frequency spectra to the counterion type proves the existence of the ion-phosphate modes.  相似文献   

19.
The infrared and Raman spectra of CH3CH2CN, CH3CD2CN, and CD3CH2CN, and the infrared spectrum of CH3CH213CN were investigated in detail between 6000 and 100 cm−1. Some infrared measurements of other isotopic species are also reported and partial assignments given. All fundamentals of propionitrile-d0, -d2, -d3, and -13CN were assigned, together with a large number of mainly binary combination bands for which a general method of assignment is given. Several Fermi resonances were detected and the unperturbed positions of some of the levels involved were calculated. Special attention was paid to the CH stretching vibrations for which persisting wrong assignments exist in the literature, and to the methyl torsion frequencies which were determined for the four isotopic species above. A valence force field was calculated, and the potential energy distribution of the normal vibrations is tabulated.  相似文献   

20.
R P Singh  R N Singh 《Pramana》1988,30(3):217-223
The infrared and laser Raman spectra of 2, 3 dichloro aniline and 2, 6 dichloro aniline have been recorded. The vibrational spectra have been analysed assumingC s andC 2v point groups for 2, 3 dichloro aniline and 2, 6 dichloro aniline respectively. Assignments for fundamental vibrations, combination and overtone frequencies and internal modes of vibration of amino group have been proposed.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号