摘要:

AbstractThe Raman (4000–10 cm−1) and infrared (4000–50 cm−1) spectra of gaseous and solid 1,1,1,3,3,3‐hexafluoro‐2‐propanimine, (CF3)2CNH, were recorded. Additionally, the Raman spectrum of the liquid was recorded and qualitative depolarization values were obtained. A complete vibrational assignment for the normal modes utilizingCssymmetry is proposed based on band contours, depolarization values and group frequencies. The assignment is supported by a normal coordinate calculation utilizing a modified valence force field to calculate the frequencies and potential energy distribution of the normal modes. A CF3torsional mode was observed in the Raman spectrum of the liquid at approximately 60 cm−1, from which a periodic barrier of 5.0 kcal mol−1(1 kcal = 4.184 kJ) was calculated. The results are compared with similar data for some corr

ISSN:0377-0486    

DOI:10.1002/jrs.1250200802

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractDetailed IR and Raman data for methyl thiolfluoroformate, FC(O)SCH3, point to the existence of atrans(F, CH3) conformer withCssymmetry in both the vapour and liquid phases. For all but the torsional modes of this conformer, wavenumbers are reported and were used to calculate an approximate force field. The study was complemented with the characterization of the compound using the13C19F and1H NMR, UV and mass spectra. A semi‐empirical calculation was performed for the molecule, and the deduced force constants were compared with those derived from experimental dat

ISSN:0377-0486    

DOI:10.1002/jrs.1250200803

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractRaman spectra of carefully purified (n‐C4H9)4N+AuI2−(TBA‐AuI2) were measured between 89 K and room temperature. The bands observed around 110 cm−1in one of the previously reported spectra are ascribed to I3−impurity. Spectra of TBA‐AuI2and TBA‐I3were compared, and the principal bands assigned. The resonance Raman effect of I3−makes its Raman bands prominent in the impure TBA‐AuI2samples. The crystal symmetries of the above two salts at low temperature are

ISSN:0377-0486    

DOI:10.1002/jrs.1250200804

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe polarized IR and Raman spectra of 2‐naphthol as a single crystal, in solution and as a KBr pellet or powder, and the inelastic incoherent neutron scattering spectra of the powder were measured and compared with the corrresponding naphthalene spectra. The previous assignments of fundamental vibrations were confirmed, except for the in‐plane and out‐of‐plane OH bending modes in the crystal. The medium‐dependent relative intensities and frequencies of the vibrational bands are interpreted in terms of the competition between an intramolecular charge transfer interacting with vibrations (vibronic coupling) and hydro

ISSN:0377-0486    

DOI:10.1002/jrs.1250200805

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractPolarization‐sensitive CARS spectra of a 5.7 × 10−3mol dm−3flavin adenine dinucleotide (FAD) solution were recorded under preresonance conditions at a pump wavelength of 532 nm. The depolarization ratios of the vibrations are shown to be close to the depolarization ratio of the non‐resonant background. This results in a severe reduction of the vibration resonant signal (a factor of 700‐900) in the polarization CARS spectrum, and a poor improvement in the ratio of the resonant signal and the non‐resonant background (<10).In this context, a non‐resonant background suppression technique is discussed and demonstrated for 5.7 × 10−3and 1.4 × 10−3mol dm−3FAD solutions excited at 532 nm; the non‐resonant susceptibility of the walls of the cuvette, which contains the FAD solution, is used to compensate the non‐resonant signal contribution of the solution. An improvement in the signal‐to‐noise ratio of ca. 50 is achieved at the cost of a factor of 30 in the resonant signal strength. Lorentzian‐shaped spectral bands are obtained, facilitating the determination of band position, width and intensity. Line shape parameters and depolarization ratios for FAD are extracted from the presented spectra by curve fitting. The signal strength and background suppression achieved with these techniques and the resonance CARS technique (at a pump wavelength of 48

ISSN:0377-0486    

DOI:10.1002/jrs.1250200806

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe temperature dependence of the Raman scattering from a single crystal of acetanilide (ACN‐H) and fully deuterated acetanilide (ACN‐D) in the low‐frequency (phonon) and CO stretching regions was studied. The observed normal behaviour of the frequency shift of the CO stretching modes in ACN‐D, raises questions concerning several theoretical models previously proposed to explain the peculiar behaviour with temperature of theA1gstretching modes observed in ACN‐H. The forms of the low‐frequency Raman spectra for ACN‐H and ACN‐D are very similar, except in the frequency range 70‐120 cm−1, where an additional mode (denoted D′) is seen in the Raman spectrum of ACN‐D. A strong temperature dependence of the frequency of this band is observed. The origin of t

ISSN:0377-0486    

DOI:10.1002/jrs.1250200807

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractRaman spectra of Mg(ClO4)2NaNCSH2O mixtures were analysed as a function of the concentration ratio of the components at ambient and elevated temperatures. The strong perturbation of the thiocyanate spectrum observed in the regions of the ν1and ν3vibrations is interpreted in terms of complex formation. Band intensity measurements of resolved bands gave evidence for two complex species: [MgNCS]+and [Mg(NCS)2], the former being discernible over the whole concentration range studied. The variations in the spectrum of theTdperchlorate ion at very low water‐to‐salt molar ratios are explained as indicating a coordination of ClO4−unit and lowering of the sym

ISSN:0377-0486    

DOI:10.1002/jrs.1250200808

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe Raman and infrared spectra ofo‐,m‐ andp‐fluoronitrobenzenes,o‐,m‐ andp‐chloronitrobenzenes,m‐ andp‐bromonitrobenzenes ando‐,m‐ andp‐iodonitrobenzenes were measured. Far‐infrared and Raman polarization measurements were made wherever possible. A normal coordinate analysis was carried out for both the in‐plane and out‐of‐plane vibrations of these molecules using an 82‐parameter modified valence force field. An overlay least‐squares technique was employed to refine the force constants using 378 frequencies of the molecules to obtain a converged set of meaningful force constants. The reliability of the force constants so obtained was tested by making a zero‐order calculation foro‐bromonitrobenzene. The potential energy distributions and eigenvectors calculated in the process were used to make unambiguous vibrationa

ISSN:0377-0486    

DOI:10.1002/jrs.1250200809

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractIn order to obtain the Raman spectra of small molecules inside proteins (or other large macromolecules) and/or small molecular groups of a protein, techniques were developed to perform sensitive Raman difference spectroscopy. The macromolecule–small molecule complex Raman spectrum is taken in addition to the Raman spectrum of the macromolecule, and the two are computer subtracted. For studies on proteins, it is necessary to use optical multichannel detectors, as spectrometers employing photomultiplier detectors are too slow optically to collect signals from dilute samples. The apparatus is described and characterized in detail. A subtraction fidelity of 0.1% can be achieved for samples, such as proteins, which contain broad bands in their Raman spectra. Hence it is possible to obtain fairly good Raman spectra of very small molecular groups inside proteins. An example from recent work is presente

ISSN:0377-0486    

DOI:10.1002/jrs.1250200810

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe interaction ofp‐benzoquinone with proline, pyrrolidine, trytophan and glutathione was investigated by resenance Raman spectroscopy. The intensely coloured solutions formed show an absorption maximum around 530 nm and the excitation of the Raman spectra in resonance conditions indicated in all cases an enhancement of several benzoquinone modes. Such behaviour strongly suggests the formation of an n–π* charge‐transfer complex, as suggested previously by other workers. The ESR spectra of the coloured solutions preclude the benzoquinone anion radical as the main chromophoric species in so

ISSN:0377-0486    

DOI:10.1002/jrs.1250200811

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY