Vibrational spectra and rotational isomerism of ethanethiol and ethanethiol-D1

1985 ◽  
Vol 63 (7) ◽  
pp. 1708-1712 ◽  
Author(s):  
Hans Wolff ◽  
Jerzy Szydlowski
Keyword(s):  
Raman Spectrum ◽  
Infrared Spectra ◽  
Low Temperatures ◽  
Room Temperature ◽  
Rotational Isomerism ◽  
Simultaneous Presence ◽  
Bending Vibration ◽  
Doublet Structure ◽  
Vibrational Bands ◽  
Rocking Vibration

The infrared spectra of gaseous, liquid, and solid C2H5SD, and the Raman spectrum of the liquid compound are analyzed and the corresponding spectra of C2H5SH were reinvestigated under improved conditions. In the deuterated compound the CH2 rocking vibration does not interact with the SD bending vibration and therefore does not split into vibrations of the conformers. The measurements suggest for gaseous and liquid C2H5SH and C2H5SD the simultaneous presence of the trans and gauche conformers, appearing at room temperature in the ratio of the order of 1:3. In analogy to solid C2H5SH, the exclusive presence of the gauche conformers can be inferred for solid C2H5SD. The spectra reported in the literature for the C2H5SH molecules embedded in matrices at low temperatures permit a similar interpretation. The doublet structure observed for the vibrational bands, not only of pure solid C2H5SH and C2H5SD but also of their solid mixtures, may be due to non-equivalent sites of the unit cell.

A Raman and infrared spectroscopic study of triethylenediamine (DABCO) and its protonated forms

1988 ◽  
Vol 66 (5) ◽  
pp. 1249-1257 ◽  
Author(s):  
David A. Guzonas ◽  
Donald E. Irish
Keyword(s):  
Raman Spectrum ◽  
Spectroscopic Study ◽  
Infrared Spectra ◽  
Infrared Spectroscopic Study ◽  
Protonated Forms ◽  
Infrared Spectroscopic ◽  
Vibrational Bands

The Raman and infrared spectra of DABCO have been measured as a function of the pH, and the vibrational bands of the two protonated forms of DABCO have been tabulated and assigned. The frequencies of several of the Raman bands were found to exhibit substantial shifts upon protonation, and the appearance of the Raman spectrum in the region between 900 and 1100 cm−1 in particular shows differences which can be used to differentiate between the three forms of DABCO. The values of the two pKa's were determined from the intensity versus pH plots for the three species.

Infrared Spectra of Water in Crystalline Hydrates: KSnCl3•H2O, an Untypical Monohydrate

1974 ◽  
Vol 52 (16) ◽  
pp. 2928-2931 ◽  
Author(s):  
Michael Falk ◽  
Chung-Hsi Huang ◽  
Osvald Knop
Keyword(s):  
Hydrogen Bonds ◽  
Infrared Spectra ◽  
Low Temperatures ◽  
Room Temperature ◽  
Water Molecules ◽  
Crystalline Hydrates

Infrared spectra of polycrystalline KSnCl3•H2O were recorded between 4000 and 300 cm−1 at different degrees of deuteration and at temperatures between 30 and −160 °C. At low temperatures the spectra show a complexity indicative of the presence of several crystallographically distinct water molecules. These molecules occupy sites with nearly identical environments and at room temperature are spectroscopically indistinguishable. The environment of each of these molecules is asymmetric. Hydrogen bonds are very weak and probably highly bent. The water molecules are less separated from one another than in K2SnCl4•H2O and may share their potassium neighbors.

THE INFRARED SPECTRA AND PHASE TRANSITIONS OF SOLID PIPERIDINIUM HALIDES

1962 ◽  
Vol 40 (4) ◽  
pp. 615-621 ◽  
Author(s):  
A. Cabana ◽  
C. Sandorfy
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Infrared Spectra ◽  
Low Temperatures ◽  
Room Temperature ◽  
Solid Films

The infrared spectra of solid films of piperidinium halides were measured at both room temperature and low temperatures. The spectra of the chloride and the bromide are not appreciably affected by cooling, but the spectrum of the iodide exhibits spectacular changes. These changes are explained by assuming the occurrence of a phase transition at about −15 °C. The possibility of a "chair" → "boat" interconversion is also discussed.

Vibrational Spectra and Normal Coordinate Analysis of Disulfuryl Difluoride S2O5F2 and Diselenonyl Difluoride Se2O5F2

1993 ◽  
Vol 58 (3) ◽  
pp. 517-529 ◽  
Author(s):  
Jiří Toužín ◽  
Miloš Černík
Keyword(s):  
Raman Spectrum ◽  
Force Field ◽  
Raman Spectra ◽  
Infrared Spectra ◽  
Vibrational Spectra ◽  
Room Temperature ◽  
Normal Coordinate Analysis ◽  
Normal Coordinate ◽  
Valence Force Field ◽  
Overlapping Bands

Raman spectra (1 600 - 100 cm-1) of liquid S2O5F2 and Se2O5F2 and infrared spectra of liquid and gaseous S2O5F2 were measured. A modified general valence force field was used for their interpretation by normal coordinate analysis. Refinement of the number of lines in the Raman spectrum of S2O5F2 by means of numerical separation of the overlapping bands led to the conclusion that liquid S2O5F2 consists at least of three rotamers at room temperature.

Infrared spectra of N-acetyl-L-α-amino-acid N'-methylamides with aliphatic side chains in non-polar solvents

1981 ◽  
Vol 46 (3) ◽  
pp. 772-780 ◽  
Author(s):  
Jorga Smolíková ◽  
Jan Pospíšek ◽  
Karel Bláha
Keyword(s):  
Amino Acid ◽  
Conformational Changes ◽  
Infrared Spectra ◽  
Room Temperature ◽  
Side Chains ◽  
Polar Solvents

Infrared spectra of the L-alanine (I), L-leucine (II), L-valine (III) and L-tert-leucine (IV) N-acetyl N'-methylamides were measured. Amides I-IV are not self associated in tetrachlormethane in the concentration 2 . 10-5 mol l-1 at room temperature and in tetrachloroethylene in the concentration 1.5 . 10-4 mol l-1 at temperatures above 65° C. True conformational changes are observable only with the least flexible amide IV which exists at room temperature in a C5 conformation. This conformational type is also highly populated in the valine derivative III, but is less important in the alanine and leucine derivatives I and II in which the intramolecularly bonded C7 and the distorted hydrogen-nonbonded conformations contribute seriously.

scholarly journals Resonanz-Raman-Effekt von Thiocyanatkomplexen einiger Übergangsmetalle

1970 ◽  
Vol 25 (10) ◽  
pp. 1394-1400 ◽  
Author(s):  
W. Krasser ◽  
H. W. Nürnberg
Keyword(s):  
Raman Spectrum ◽  
Infrared Spectra ◽  
High Intensity ◽  
High Frequency ◽  
Resonance Raman ◽  
Ammonium Salts ◽  
Iron Cobalt ◽  
Decay Products ◽  
Thiocyanate Complexes ◽  
Resonance Raman Spectra

Abstract The thiocyanates of the transition metals iron, cobalt, copper as well as of rhenium and of tech-netium appear in solution as strongly coloured complexes. The resonance raman bands in the sol-vent acetonitrile are investigated. To achieve an unambiguous identification the infrared spectra were recorded too. The change in position and structure of the acetonitrile bands indicates strong complexation of iron, cobalt and copper with acetonitrile, thus indicating the existence of mixed acetonitrile-thiocyanate complexes. The resonance raman spectra of the rhenium-and technetium-thiocyanates present as tetramethyl ammonium salts show however no raman-and infrared-bands of complexed acetonitrile molecules.In the raman spectrum of the thiocyanates of iron, cobalt and copper mainly the totally sym-metric C≡N, S-C, Me-S and Me-N valence vibrations are observed, among which the S-C vibration shows a remarkably high intensity. Besides, a series of bands is obtained which is inter-preted partly as caused by decay products, and partly as bands of complexed acetonitrile. The thiocyanates of rhenium and of technetium show the three possible valence vibrations only. The high frequency of the S-C valence indicates the N-coordination of the thiocyanate group.

scholarly journals Review of Multi-Physics Modeling on the Active Magnetic Regenerative Refrigeration

2021 ◽  
Vol 26 (2) ◽  
pp. 47
Author(s):  
Julien Eustache ◽  
Antony Plait ◽  
Frédéric Dubas ◽  
Raynal Glises
Keyword(s):  
Magnetic Field ◽  
Low Temperatures ◽  
Room Temperature ◽  
State Of The Art ◽  
Vapor Compression ◽  
Crucial Step ◽  
Potential Alternative ◽  
Vapor Compression Refrigeration ◽  
Preliminary Study ◽  
Physics Modeling

Compared to conventional vapor-compression refrigeration systems, magnetic refrigeration is a promising and potential alternative technology. The magnetocaloric effect (MCE) is used to produce heat and cold sources through a magnetocaloric material (MCM). The material is submitted to a magnetic field with active magnetic regenerative refrigeration (AMRR) cycles. Initially, this effect was widely used for cryogenic applications to achieve very low temperatures. However, this technology must be improved to replace vapor-compression devices operating around room temperature. Therefore, over the last 30 years, a lot of studies have been done to obtain more efficient devices. Thus, the modeling is a crucial step to perform a preliminary study and optimization. In this paper, after a large introduction on MCE research, a state-of-the-art of multi-physics modeling on the AMRR cycle modeling is made. To end this paper, a suggestion of innovative and advanced modeling solutions to study magnetocaloric regenerator is described.

scholarly journals On the measurement of the ratio of the specific heats using small volumes of gas.—The ratios of the specific heat of air and of hydrogen at atmospheric pressure and a temperatures between 20°C. and —183°C

1925 ◽  
Vol 107 (743) ◽  
pp. 510-543 ◽  
Keyword(s):  
Systematic Error ◽  
Low Temperatures ◽  
Room Temperature ◽  
Expansion Chamber ◽  
Small Vessels ◽  
Specific Heats ◽  
Large Expansion ◽  
Before And After ◽  
The One ◽  
Chamber Capacity

Introduction .—In nearly all the previous determinations of the ratio of the specific heats of gases, from measurements of the pressures and temperature before and after an adiabatic expansion, large expansion chambers of fror 50 to 130 litres capacity have been used. Professor Callendar first suggests the use of smaller vessels, and in 1914, Mercer (‘Proc. Phys. Soc.,’ vol. 26 p. 155) made some measurements with several gases, but at room temperature only, using volumes of about 300 and 2000 c. c. respectively. He obtained values which indicated that small vessels could be used, and that, with proper corrections, a considerable degree of accuracy might be obtained. The one other experimenter who has used a small expansion chamber, capacity about 1 litre, is M. C. Shields (‘Phys. Rev.,’ 1917), who measured this ratio for air and for hydrogen at room temperature, about 18° C., and its value for hydroger at — 190° C. The chief advantage gained by the use of large expansion chambers is that no correction, or at the most, a very small one, has to be made for any systematic error due to the size of the containing vessels, but it is clear that, in the determinations of the ratio of the specific heats of gases at low temperatures, the use of small vessels becomes a practical necessity in order that uniform and steady temperature conditions may be obtained. Owing, however, to the presence of a systematic error depending upon the dimensions of the expansion chamber, the magnitude of which had not been definitely settled by experiment, the following work was undertaken with the object of investigating the method more fully, especially with regard to it? applicability to the determination of this ratio at low temperatures.

scholarly journals Preparation and the Microwave and Infrared Spectra of Vinyl Ketene

1979 ◽  
Vol 34 (11) ◽  
pp. 1269-1274 ◽  
Author(s):  
Erik Bjarnov
Keyword(s):  
Dipole Moment ◽  
Gas Phase ◽  
Infrared Spectra ◽  
Room Temperature ◽  
Normal Modes ◽  
Spectroscopic Constants ◽  
Electrical Dipole ◽  
Electrical Dipole Moment ◽  
Vacuum Pyrolysis ◽  
Modes Of Vibration

Vinyl ketene (1,3-butadiene-1-one) has been synthesized by vacuum pyrolysis of 3-butenoic 2-butenoic anhydride. The microwave and infrared spectra of vinyl ketene in the gas phase at room temperature have been studied. The trans-rotamer has been identified, and the spectroscopic constants were found to be Ã= 39571(48) MHz, B̃ = 2392.9252(28) MHz, C̃ = 2256.0089(28) MHz, ⊿j = 0.414(31) kHz, and ⊿JK = - 34.694(92) kHz. The electrical dipole moment was found to be 0.987(23) D with μa = 0.865(14) D and μb = 0.475(41) D. A tentative assignment has been made for 17 of the 21 normal modes of vibration

Infrared spectra of the ammonium ion in crystals. Part VIII. Spectroscopic criteria of highly-bent hydrogen bonds

1980 ◽  
Vol 58 (9) ◽  
pp. 867-874 ◽  
Author(s):  
Osvald Knop ◽  
Wolfgang J. Westerhaus ◽  
Michael Falk
Keyword(s):  
Low Temperature ◽  
Hydrogen Bonds ◽  
Infrared Spectra ◽  
Room Temperature ◽  
Ammonium Ion ◽  
Temperature Transition ◽  
Increasing Temperature

Available evidence suggests that (1) the stretching frequencies of highly-bent hydrogen bonds decrease with increasing temperature, regardless of whether the bonds are static or dynamic in character, to a single acceptor or to several competing acceptors; and (2) departures from symmetric trifurcation (or bifurcation) toward asymmetric situations lower the stretching frequency. In further support of these criteria isotopic probe ion spectra between 10 K and room temperature have been obtained for taurine and for trigonal (NH4)2MF6 (M = Si, Ge, Sn, Ti). Evidence of a low-temperature transition at 100(10) K in trigonal (NH4)2SnF6 is presented, and existence of the previously reported transition at 38.6 K in trigonal (NH4)2SiF6 is confirmed. Symmetry changes associated with these transitions are discussed.

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