ISSN:0377-0486    

DOI:10.1002/jrs.1250220902

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractFourier transform Raman spectra in the near‐IR region and surface‐enhanced Raman (SER) spectra were used to obtain the vibrational spectra of barbituric acid and its anion, since their ordinary Raman spectra cannot be obtained owing to a strong fluorescence emission. Based on the present data and literature IR data, a tentative vibrational assignment is proposed for the two species. In addition, the SER spectra of barbiturate anion adsorbed on a silver electrode in borate buffer (pH 8.4) were used to infer the geometry of adsorption, which probably involves the participation of at least one of the carbonyl groups, although a more precise definition of the geometry of adsorption depends on additional d

ISSN:0377-0486    

DOI:10.1002/jrs.1250220903

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThis report describes the use of an efficient and convenient silver substrate in the development of surface‐enhanced near‐infrared Fourier transform (FT) Raman scattering as a useful analytical technique that compliments the bulk FT‐Raman method. The SERS‐active material, prepared in the form of solid silver powder by means of chemical precipitation, is particularly well suited for surface Raman enhancement in the near‐IR region. To demonstrate the unique features of surface‐enhanced FT‐Raman, a detailed spectroscopic study of the charge‐transfer donor molecule tetrathiafulvalene (TTF) adsorbed on the silver powder is also reported. The advantages of near‐IR FT‐SERS over bulk FT‐Raman include the ability to analyze dilute solution samples, the acquisition of Raman spectra for near‐IR fluorescent compounds and new vibrational information concerning the mixed‐valence behavior of su

ISSN:0377-0486    

DOI:10.1002/jrs.1250220904

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractIn principle, Raman measurements provide information about vibrational frequencies and intensities. Working with polarized light provides additional information about the Raman scattering tensor components. The special conditions relating to the near‐infrared‐Fourier transform (NIR‐FT) Raman technique may preclude adaptation of some of the techniques employed for measurements with linear polarized light in ‘classical’ Raman spectroscopy in the visible range. The experimental conditions for measurements of depolarization ratios of liquids (benzene, mesitylene,p‐xylene and carbon tetrachloride) using different experimental geometries with an NIR‐FT‐Raman spectrometer were elucidated. The FT technique allows the rapid and simple determination of depolarization ratios with a quality sufficient to assign the bands to totally or non‐totally symmetric species. The possibility of determining the orientation of molecules in non‐crystalline solids is also demonstrated. Finally, the feasibility of measuring the different components of the Raman scattering tensor of a single crystal of sodium chl

ISSN:0377-0486    

DOI:10.1002/jrs.1250220905

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractAs part of a general study on the behaviour of acetaldehyde as an atmospheric pollutant, the Raman and infrared spectra are presented of acetaldehyde isolated in argon and nitrogen matrices. Using the observed frequencies, the thermodynamic functions were calculated. By obtaining the vibrational spectra at low temperature, it was possible to assess the results of the photochemical studies that have been done in matrices with both argon and nitrogen gases. The main products in the photochemical decomposition of acetaldehyde under the conditions adopted are methane and carbon monoxide.

ISSN:0377-0486    

DOI:10.1002/jrs.1250220906

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractA fiber‐optic sample cell designed for use in the near‐infrared region is described. For Fourier transform (FT) Raman spectroscopy, Nd:YAG laser radiation is transmitted to the sample through one fiber bundle, while a second fiber bundle collects and transfers the scattered light to the source compartment of an infrared interferometer equipped with a CaF2beam splitter and an InGaAs detector. Because the two fiber bundles are mounted in the aluminum body of the cell, virtually no optical alignment is required. In addition to its utility in FT‐Raman spectroscopy, the cell may be used for obtaining near‐infrared absorption spectra of liquids and reflectance spectra of solids without changing its configuration. Examples of the many uses of the cell are provided, and modifications which would potentially improve its efficiency and expand its capabilities are di

ISSN:0377-0486    

DOI:10.1002/jrs.1250220907

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractWe (J. R. Durig and T. S. Little, Department of Chemistry, University of South Carolina, Columbia, SC, USA) recently had an opportunity to visit the Molecular Spectroscopy Laboratory housed in the Institute of Chemistry at the University of São Paulo. This laboratory, directed and maintained by Professor O. Sala, is steeped in the history of Raman spectroscopy. The presence of the original Raman spectrograph, hand tooled by Professor Hans Stammreich in the 1940s, with the helium lamps still intact and located near the most modern of Raman equipment, created an unforgettable air of nostalgia. We kindly requested one of Professor Sala's close co‐workers (P. S. Santos) to provide the present article on the historical perspectives and significance of Raman spectroscopy at the University of São Paulo. We are pleased to present this overview to the readership of theJournal of Raman Spectrosc

ISSN:0377-0486    

DOI:10.1002/jrs.1250220908

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe Raman and infrared spectra of methyltrans‐cinnamate were measured as a function of temperature in the liquid and solid phases. The temperature dependence of the band intensities established the presence of two conformers in the liquid phase (thes‐cisands‐transforms, with CCCO dihedral angles equal to 0° and 180°, respectively; ΔH(s‐trans)‐(s‐cis)= 3.43 ± 0.84 kJ mol−1) and led to the conclusion that the thermodynamically most stables‐cisform is the only

ISSN:0377-0486    

DOI:10.1002/jrs.1250220909

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe Raman spectrum of a CuSO4· 5H2O single crystal was measured at 95 K. The assignment of the internal modes of the molecular complex Cu2+(H2O)4and of differently bonded water molecules is discussed

ISSN:0377-0486    

DOI:10.1002/jrs.1250220910

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractTemperature‐dependent first‐order Raman scattering studies in the range 30–290 K were carried out in LiCsSO4in order to investigate its phonon spectra in relation to the phase transitions in the crystal. Complete spectra were obtained for thez(xx)yandz(xz)ygeometries. A careful analysis of the spectra shows that both the low‐ and high‐energy Raman modes exhibit variations either in frequency or intensity or both with temperature of the crystal, indicating that theD2knormal phase undergoes a transition at theTi(202 K) and one to the commensurate phase atca160 K (Tc). Below theTc, in theC2νphase, the lattice mode at 44 cm−1was observed to be a soft phonon with its frequency decreasing to 32 cm−1at 30 K, indicating the possibility of a new structural phase transition of unlocking type in the crystal at a temperatureTubelow 20 K. Another observation is the oscillating behaviour of Rayleigh scattering near the phase trans

ISSN:0377-0486    

DOI:10.1002/jrs.1250220911

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY