Journal ArticleDOI
Molekül- und Gitterschwingungen des orthorhombischen und ferroelektrischen Thioharnstoffs I. Temperaturabhängigkeit der Infrarot- und Ramanspektren und der berechneten Entropie
Von B. Schrader,W. Meier,K. Gottlieb,H. Agatha,H. Barentzen,P. Bleckmann +5 more
- Vol. 75, Iss: 12, pp 1263-1278
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TLDR
In this paper, the spectra of the deuterated polycrystalline thiourea are obtained using polarized radiation and a complete assignment of all optically active molecular and lattice vibrations is given.Abstract:
Die Infrarot- und Ramanspektren von Thioharnstoff-Einkristallen bei 300 und 120°K werden mit polarisierter Strahlung aufgenommen. Zusatzlich werden die Spektren der deuterierten Verbindung an polykristallinen Proben und die Fern-Infrarot-Spektren an pulverformigen Proben gewonnen. Damit ist eine vollstandige Zuordnung der inneren und der Gitterschwingungen moglich. Durch Kopplung uber zwischenmolekulare Kraftkonstanten und durch Dipol-Wechselwirkung spalten die inneren Schwingungen um ca. 10 — 40 cm−1 auf. Die Umwandlung in die ferroelektrische Phase ist an Aufspaltungen, Intensitatsveranderungen und Frequenzsprungen sichtbar. Aus den beobachteten Daten wird fur den Bereich 25 bis 350 °K die Entropie berechnet, sie ist in guter Ubereinstimmung mit experimentellen Werten.
Infrared and Raman spectra of single crystals of thiourea at 300 and 120°K are recorded using polarized radiation. Furthermore the spectra of the deuterated polycrystalline thiourea are obtained. A complete assignment of all optically active molecular and lattice vibrations is given. Vibrational coupling by intermolecular atom-atom force constants and by dipole interaction lead to a factor group splitting to the order of 10–40 cm−1. The phase transition into the ferroelectric modification is seen from band splittings, variations of intensity and frequency jumps. From the observed data the entropy is calculated for the region from 25 to 350°K. Results are in good agreement with observed values.read more
Citations
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Journal ArticleDOI
Soft-mode spectroscopy: Experimental studies of structural phase transitions
TL;DR: In this article, the experimental studies of displacive phase transitions in solids are summarized, focusing on inelastic light scattering and neutron scattering; related infrared reflectivity measurements, as well as x-ray and EPR analyses are also summarized.
Journal ArticleDOI
Vibrational spectroscopic study of zinc tris(thiourea) sulphate, a new organometallic non-linear optical crystal
TL;DR: In this article, the vibrational spectra of zinc tris(thiourea) sulphate (ZTS), a semiorganic nonlinear optical crystal, were record- ed to determine the symmetries of molecular vibrations.
Journal ArticleDOI
Growth and characterization of nonlinear optical crystal zinc tris (thiourea) sulphate in presence of l-arginine
Sweta Moitra,Tanusree Kar +1 more
TL;DR: In this paper, a single crystal growth and characterization of zinc tris (thiourea) sulphate (ZTS) doped with different molar concentrations of basic amino acid l -arginine was studied.
Journal ArticleDOI
Conformational preferences and internal rotation in alkyl- and phenyl-substituted thiourea derivatives.
TL;DR: Analysis of phenylthiourea reveals that a trans isomer in a syn geometry is the global minimum, whereas a cis isomers in an anti geometry is a local minimum with a relative energy of 2.7 kcal/mol.
References
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Journal ArticleDOI
Infrared Absorption Spectra of Inorganic Coördination Complexes. XIV. Infrared Studies of Some Metal Thiourea Complexes1a
Journal ArticleDOI
Infrared Absorption Spectra of Urea, Thiourea, and Some Thiourea‐Alkali Halide Complexes
TL;DR: In this paper, the infrared spectra of urea, thiourea, and thiamourea complexes with cesium bromide, potassium iodide, potash, potassium bromides, sodium ionide, and sodium iodide have been observed from 2 to 40 μ.
Journal ArticleDOI
Ferroelectric Behavior of Thiourea
G. J. Goldsmith,J. G. White +1 more
TL;DR: The dielectric constant and the ferroelectric, pyroelectric and piezoelectric properties of thiourea crystals have been measured in the temperature range 90°K to 300°K.
Journal ArticleDOI
A neutron diffraction determination of the crystal structures of thiourea and deuterated thiourea above and below the ferroelectric transition
M. M. Elcombe,J. C. Taylor +1 more
TL;DR: In this paper, the structures of thiourea, SC(NH2)2 and deuterated SC(ND 2)2 have been determined at room and liquid nitrogen temperatures from three-dimensional neutron diffraction data.