The Raman Spectrum of Tetramethyldiborane. Apparatus for the Production of Raman Spectra at Low Temperatures

1951 ◽  
Vol 73 (5) ◽  
pp. 2306-2307 ◽  
Author(s):  
Bernard Rice ◽  
J. M. Gonzalez Barredo ◽  
T. F. Young
Keyword(s):  
Raman Spectrum ◽  
Raman Spectra ◽  
Low Temperatures

scholarly journals Experiments on the raman effect at very low temperatures

1933 ◽  
Vol 141 (845) ◽  
pp. 535-549 ◽  
Keyword(s):  
Raman Spectrum ◽  
Raman Spectra ◽  
Low Temperatures ◽  
Vibrational Energy ◽  
Raman Effect ◽  
Energy Levels ◽  
Solid Carbon Dioxide ◽  
Nitrogen Tetroxide ◽  
Primary Object ◽  
Vibrational Energy Levels

Hitherto, the experiments which have been carried out oil the Raman effect at low temperatures have been performed on substances of which the Raman spectra were unobtainable, or only obtainable with difficulty, at ordinary temperatures. Thus Daure* has obtained the Raman spectra of liquid methane, ethylene, ethane, propane, and ammonia, while McLennan and his co-workers have studied those of liquid hydrogen, oxygen, nitrogen, methane, helium, nitrous oxide and solid carbon dioxide. The primary object in these researches was to obtain the spectrum of the substance, and the influence of temperature on the spectrum has received very little attention. While the present work began as an attempt to obtain the Raman spectrum of nitrogen tetroxide, it has become increasingly evident in the course of it that the study of Raman spectra at very low temperatures may well prove to be a very fruitful field of research. It is clear that there will be at least two distinct possible effects of a change in temperature of the scattering substance on its Raman spectrum. If the change in temperature causes a change in the molecular structure of the substance (such as association of simple molecules into more complex aggregates, or a change in the crystalline form of the substance), then one may expect the appearance of new lines in the spectrum. Secondly, a change in temperature will result in a new distribution of the molecules in the various rotational and vibrational energy levels ; the effect of this will be to alter the character of the individual lines and bands in the spectrum without, however, giving rise to any new lines. The following paper gives a description of a new and very simple apparatus for the observation of Raman spectra at low temperatures, together with the results and discussion of the preliminary experiments on a few simple substances.

The resonance Raman spectra and excitation profiles of some 4-sulfamylazobenzenes

1977 ◽  
Vol 55 (9) ◽  
pp. 1444-1453 ◽  
Author(s):  
Kamal Kumar ◽  
P. R. Carey
Keyword(s):  
Raman Spectrum ◽  
Raman Spectra ◽  
Resonance Raman ◽  
Valence Bond ◽  
Wavelength Dependence ◽  
Accurate Estimation ◽  
Intensity Changes ◽  
Stretching Vibration ◽  
Resonance Raman Spectra ◽  
Frequency Changes

The resonance Raman spectra of three pharmacologically important sulfonamides, 4-sulfamyl-4′-dimethylaminoazobenzene (1), 4-sulfamyl-4′-hydroxyazobenzene (2), and 4-sulfamyl-4′-aminoazobenzene (3), are compared with those of analogues lacking the sulfonamide group. The —SO2NH2 moiety does not directly contribute intense or moderately intense bands to the resonance Raman spectra of 1, 2, and 3. However, —SO2NH2 ionization is reflected by frequency changes in a band near 1140 cm−1 and intensity changes in the 1420 cm−1 region. The normal Raman spectrum of 2 confirms that the intensity changes reflect —SO2NH2 ionization rather than unrelated changes in vibronic coupling. The effect of —OH ionization on the resonance Raman spectrum of 2 emphasizes that caution must be exercised when relating spectral perturbations to changes in contributions from valence bond type structures. Resonance Raman excitation profiles for the 1138, 1387, and 1416 cm−1 bands of 2 show that these bands gain intensity by coupling with the electronic transitions in the 240 to 450 nm region and that, more than 1000 cm−1 to the red of λmax, the wavelength dependence can be closely reproduced by the FB type terms of Albrecht and Hutley. The excitation profile for each band shows evidence for structure in the 470 nm region, although lack of sufficient excitation wavelengths prevents accurate estimation of the spacing. Under conditions of rigorous resonance the intense Raman lines all occur in the 1400 cm−1 region, i.e. they are 'bunched' in the region known to contain the —N=N— stretching vibration.

Studies of the Jahn - Teller effect IV. The vibrational spectra of spin-degenerate molecules

1962 ◽  
Vol 255 (1050) ◽  
pp. 31-53 ◽  
Keyword(s):  
Raman Spectrum ◽  
Raman Spectra ◽  
Vibrational Spectra ◽  
Physical Theory ◽  
Vibronic Coupling ◽  
Infra Red ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Active Vibration ◽  
Degenerate States

The physical theory necessary for interpreting the vibrational spectra of spin-degenerate molecules is developed in this paper. Particular attention is paid to those molecules whose behaviour is expected to be markedly different from that of both orbitally non-degenerate molecules and those with purely spatial degeneracy. These include certain Kramers degenerate molecules, whose Raman spectra are expected to contain reverse-polarized contributions, and also tetrahedral and octahedral molecules in fourfold degenerate states. The case of a fourfold degenerate octahedral molecule is investigated in the limits of strong vibronic coupling by one of the Jahn—Teller active vibrations (e g and t 2g ). It turns out that the forbidden t 2u vibration may be infra-red active, that the Raman spectrum may contain reverse-polarized contributions and that both infra-red and Raman spectra may contain strong progressions of bands involving multiple excitations of the vibronically active vibration.

The Change in the Raman Spectra of Chloroprene and Isoprene in the Polymerization Process

1943 ◽  
Vol 16 (4) ◽  
pp. 841-847
Author(s):  
A. Gantmacher ◽  
S. Medvedev
Keyword(s):  
Raman Spectrum ◽  
Double Bond ◽  
Raman Spectra ◽  
Polymer Molecule ◽  
Polymerization Process ◽  
High Polymer ◽  
Single Bond ◽  
Double Bonds ◽  
Continuous Background ◽  
Single Bonds

Abstract 1. When chloroprene and isoprene polymerize, besides the frequency characterizing the conjugate double bond in the monomer, there appears a higher frequency corresponding to the isolated double bond in the polymer. In the polymerization process, the intensity of the frequency of the conjugate double bond decreases and the intensity of the frequency of the isolated double bond increases. Because of the increase in the number of single bonds in the polymer, the intensity of the frequency of the single bond 1005 in the polymer is considerably greater than in the monomer. 2. Even in the case of the samples with high polymer contents (greater than 50 per cent), the intensity of the frequency of the conjugate double bond is considerably greater than the intensity of the frequency of the isolated double bond. This is attributable to the fact that part of double bonds disappear during polymerization. 3. The Raman spectra of the chloroprene and isoprene polymers differ essentially from those of the monomers. To characterize the frequencies of vibration in the polymer molecule, it is essential to investigate its Raman spectrum in a medium free of the monomer. 4. The formation of highly polymeric molecules on polymerization does not result in an increase in the intensity of the continuous background in spectrograms.

Theoretical calculations of electronic Raman effects of the NO and O2 molecules

1970 ◽  
Vol 48 (14) ◽  
pp. 1664-1674 ◽  
Author(s):  
D. W. Lepard
Keyword(s):  
Raman Spectrum ◽  
Raman Spectra ◽  
Theoretical Calculations ◽  
Diatomic Molecules ◽  
Wave Functions ◽  
Rotational Structure ◽  
Intermediate Case ◽  
First Time

This paper presents a method for calculating the relative intensities and Raman shifts of the rotational structure in electronic Raman spectra of diatomic molecules. The method is exact in the sense that the wave functions used for the calculations may belong to any intermediate case of Hund's coupling schemes. Using this method, theoretical calculations of the pure rotational and electronic Raman spectrum of NO, and the pure rotational Raman spectrum of O2, are presented. Although a calculated stick spectrum for NO was previously shown by Fast et al., the details of this calculation are given here for the first time.

scholarly journals Darstellung von Cyclopentadekaschwefel (S15) aus Titanocenpentasulfid und Sulfurylchlorid [1]

1988 ◽  
Vol 43 (9) ◽  
pp. 1151-1155 ◽  
Author(s):  
Reinhard Strauss ◽  
Ralf Steudel
Keyword(s):  
Raman Spectra ◽  
Low Temperatures ◽  
Yellow Powder ◽  
Sulfuryl Chloride ◽  
Lemon Yellow ◽  
Stretching Vibrations

Abstract Titanocene pentasulfide reacts with sulfuryl chloride under suitable conditions to give a mixture of mainly S10, S15, and S20 which can be separated by repeated crystallization and precipitation. Pure S15 is obtained as a lemon-yellow powder at low temperatures which transforms to a sticky mass at 20 °C. Solutions of S15 in CS2 are stable at 20 °C for months. Pure S15 does not decompose at 20 °C within a few hours. Raman spectra of S15 show stretching vibrations at 409-480 cm-1 and bending and torsional modes at < 270 cm-1.

Raman spectra of selenious acid at low temperatures

2000 ◽  
Vol 31 (12) ◽  
pp. 1057-1060
Author(s):  
Angela Sanders ◽  
Marilyn Louie ◽  
A. Anderson
Keyword(s):  
Raman Spectra ◽  
Low Temperatures ◽  
Selenious Acid

IR and Raman spectra of AgNO3 at low temperatures

1992 ◽  
Vol 23 (9) ◽  
pp. 509-514 ◽  
Author(s):  
Z. X. Shen ◽  
W. F. Sherman ◽  
M. H. Kuok ◽  
S. H. Tang
Keyword(s):  
Raman Spectra ◽  
Low Temperatures ◽  
Ir And Raman Spectra ◽  
Ir And Raman

Illumination- and Annealing-Induced Changes in the Infrared and Raman Spectra of a-Si:H

2001 ◽  
Vol 664 ◽  
Author(s):  
L.-F. Arsenault ◽  
S. Lebiba ◽  
E. Sacher ◽  
A. Yelon
Keyword(s):  
Raman Spectrum ◽  
Raman Spectra ◽  
Qualitative Agreement ◽  
Raman Signal ◽  
Infrared And Raman Spectra ◽  
Matrix Elements ◽  
Short Term ◽  
Phonon Peak ◽  
Induced Changes ◽  
Ir And Raman

ABSTRACTWe have investigated the changes, produced by light-soaking, in both the IR and Raman responses of the Si-Hn stretching peaks in the 2000-2100 cm−1 range. Our observations of the IR response are in qualitative agreement with those of Kong and co-workers [1]: that is, short-term light soaking produces an increase in the intensity of the signal and a simultaneous shift to lower frequency. In contrast, short-term light soaking decreases the total intensity of the Raman signal in the 2000-2100 cm−1 range, when normalized to the TO phonon peak at about 480 cm−1. In both cases, these modifications are reversed on annealing at 200° C. We suggest that these changes are attributable to alterations in the environments of the Si-Hn bonds, with the resultant transfer of intensity between IR and Raman matrix elements. Details of the evolution of the components of the Raman spectrum in the 2000-2100 cm−1 range are presented, and compared with IR changes in the same range.

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