The Vibrational Spectrum of Methyl isothiocyanate

1959 ◽  
Vol 12 (4) ◽  
pp. 601 ◽  
Author(s):  
AJ Costoulas ◽  
RL Werner
Keyword(s):  
Raman Spectrum ◽  
Vibrational Spectrum ◽  
Methyl Isothiocyanate ◽  
Infra Red ◽  
Parallel Band

Methyl isothiocyanate has been studied in the infra-red region from 10,000 to 250 cm-1 as vapour, solid, and melt, while the Raman spectrum has been recorded in the molten condition. The molecule is close to a symmetric top and the bands of the vapour exhibit contours generally similar to that type of molecule. A satisfactory assignment of all fundamentals has been made. Of interest is the pseudo-symmetric NCS stretching mode which has been assigned to the parallel band at 676 cm-1 in the vapour. In the Raman spectrum, the corresponding mode is observed as a strong polarized line at 656 cm-1.

scholarly journals The theory of the vibrations and the Raman spectrum of the diamond lattice

1948 ◽  
Vol 241 (829) ◽  
pp. 105-145 ◽  
Keyword(s):  
Raman Spectrum ◽  
Vibrational Spectrum ◽  
Frequency Shift ◽  
Raman Line ◽  
Elastic Constants ◽  
Lattice Dynamics ◽  
Ultra Violet ◽  
Force Constants ◽  
X Ray ◽  
Infra Red

The crystal structure of diamond was first determined by Bragg in 1913 from X-ray photographs; the carbon atoms are arranged at the apices and median points of interlinked tetrahedra. Born (1914) derived expressions for the three elastic constants of diamond in terms of two force constants related to the valency bonds between neighbouring atoms. But, at that time, the only experimental data available were the compressibility and the Debye characteristic temperature 0, and precise determination of the valence force constants was not possible. Meanwhile, investigation of the optical properties of diamond had produced evidence for the existence of two distinct types, one with an absorption band at 8 [i in the infra-red, the other transparent at this point. Robertson, Fox & Martin (1934) took up this problem and found that absorption in the infra-red is associated with absorption in the ultra-violet; diamonds transparent at 8y transmit much farther into the ultra-violet. Both types of diamond have Bragg’s tetrahedral structure, the same refractive index, specific gravity, dielectric constant and electron diffraction. Their infra-red spectra are identical up to 7y, and the frequency shift of the principal Raman line is the same. The derivation of the elastic constants was again considered by Nagendra Nath (1934). He extended the theory to include central forces between second neighbours in the lattice. He also suggested that the frequency shift of the principal Raman line corresponds to the relative vibration of the two carbon atoms in the unit cell, along the line joining their nuclei. Raman and his collaborators have recently (1941) put forward a new theory of lattice dynamics according to which the vibrational spectrum of a crystal consists of a few discrete lines. This is in direct contradiction to the quasi-continuous vibrational spectrum predicted by classical or quantum mechanics. On this new theory there are eight fundamental frequencies of vibration for diamond; the values of these frequencies are deduced from the observed specific heat, ultra-violet absorption and Raman spectrum, which, it is claimed, cannot be explained by ‘orthodox’ lattice dynamics. Raman (1944) has suggested that there are, not two, but four types of diamond, two with tetrahedral symmetry and two with octahedral symmetry depending on the electronic configurations, but X-ray analysis gives no indication of this and the attempts of his school to explain the observed infra-red spectra on the basis of their new lattice theory have been, up to now, unsuccessful.

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.

A reinvestigation of the vibrational spectrum of SeO2F− and the preparation and raman spectrum of SeO2F22−

1976 ◽  
Vol 7 (1-3) ◽  
pp. 43-54 ◽  
Author(s):  
Ronald James Gillespie ◽  
Paul Spekkens ◽  
John Buchanan Milne ◽  
Duncan Moffett
Keyword(s):  
Raman Spectrum ◽  
Vibrational Spectrum

scholarly journals The Raman spectrum of rock-salt

1946 ◽  
Vol 187 (1009) ◽  
pp. 188-196 ◽  
Keyword(s):  
Raman Spectrum ◽  
Rock Salt ◽  
Lattice Dynamics ◽  
Vibration Spectrum ◽  
Raman Effect ◽  
Frequency Shifts ◽  
Crystal Lattices ◽  
Absorption Frequency ◽  
Infra Red ◽  
Quartz Spectrograph

Using a non-luminescent crystal of rock-salt, a quartz spectrograph with a fine slit, and the 2536.5 A resonance radiations of mercury arc as exciter, the Raman effect in rock-salt has been studied. The spectrum exhibits nine distinct Raman lines with frequency shifts 135, 184, 202, 235, 258, 278, 314, 323 and 350 cm. -1 . The frequency shifts 235 and 184 cm. -1 representing conspicuous lines in the Raman spectrum agree as nearly as could be expected with the position of the two subsidiary infra-red absorption maxima observed by Barnes & Czerny with thin films of rock-salt. The principal infra-red absorption frequency of 163 cm. -1 is inactive in the Raman effect, but its octave is represented. The nature of the Raman spectrum to be expected is deduced on the basis of a theory due to Tamm, as also on the basis of another due to Fermi, the vibration spectrum of the rock-salt lattice being taken to be that worked out by Kellermann on the basis of the Born lattice dynamics. The results are altogether of a different nature from those actually observed experimentally in the present investigation. The conclusion is thus reached that the Born lattice dynamics does not correctly picture the vibration spectrum of the rock-salt lattice. On the other hand the observed facts, both in respect of Raman effect and infra-red absorption, fit into the theoretical picture provided by the dynamics of crystal lattices recently worked out by Sir C. V. Raman.

Schwingungsspektrum und Kristallstruktur des fünffach-koordinierten cis-Dioxo-dipicolinato-vanadat(V)-Anions / Vibrational Spectrum and Crystal Structure of the cis-Dioxo-dipicolinato-vanadium(V) Anion

1978 ◽  
Vol 33 (3) ◽  
pp. 265-267 ◽  
Author(s):  
Bernhard Nuber ◽  
Johannes Weiss ◽  
Karl Wieghardt
Keyword(s):  
Crystal Structure ◽  
Raman Spectrum ◽  
Vibrational Spectrum ◽  
Single Crystal ◽  
Diffraction Analysis ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
X Ray ◽  
Distorted Trigonal Bipyramid ◽  
Ir And Raman

Abstract cis-Dioxo-dipicolinato-vanadate(V), Crystal Structure, IR, Raman The crystal structure of Cs[V(O)2(dipic)]·H2O (dipic = pyridine-2,6-dicarboxylate) has been determined by single crystal x-ray diffraction analysis. The compound crystallizes in the monoclinic space group P21/a, with cell constants a =737.8(3), 6=1917.5(5), c = 792.9(3) pm, β= 94.87(6)°, and Z = 4. The geometry about vanadium is a distorted trigonal bipyramid containing a cis-dioxo moiety (∢ O-V-O 109.9(3)°, V=O bond lengths 161.0(6) and 161.5(6) pm). Vibrational absorptions νs(V - 0) and νas(V=O) were found at 956 and 947 cm-1 in the IR and Raman spectrum, resp.

scholarly journals The normal vibrations of carbonate and nitrate ions

1931 ◽  
Vol 134 (823) ◽  
pp. 265-277 ◽  
Keyword(s):  
Raman Spectrum ◽  
Raman Spectra ◽  
Raman Effect ◽  
Normal Modes ◽  
Potassium Nitrate ◽  
Nitrate Ions ◽  
Carbonate Ion ◽  
Infra Red ◽  
Modes Of Vibration

When the Raman effect was first discovered, it was believed that every line in the Raman spectrum referred to some characteristic vibration of the scatter­ing molecule. Later the tendency was to regard the lines as due to transitions between states of vibration of the molecule, so that the energies corresponded not to energies of vibration directly, but to differences in the energy of vibra­tion of two different modes. It is now realised that the infra-red spectrum of a substance and the Raman spectrum which it scatters give complementary information. Certain modes of vibration are represented solely in the infra­red spectrum, others are found only in the Raman spectrum, while others may appear in both spectra. Quite early a rough criterion on the basis of symmetry was put forward by Schaefer, for the determination of whether or not a particular vibration was to be expected in the Raman effect. Recently a selection rule has been formulated by Placzek; no vibration will appear as a fundamental in the Raman effect if it is such that any symmetrical operation upon it can change the signs of the displacements of the normal co-ordinates, without altering the energy. It is clear that a knowledge of the normal modes of vibration of the molecule under discussion must precede the application of any such rule, and it is the purpose of the present communication to discuss the normal modes of vibration of the carbonate and nitrate ions. In 1929 the writer showed that it was possible to obtain Raman spectra from powdered crystals, and the discovery was made when using powdered crystals of potassium nitrate. The method was applied first to carbonates and nitrates, so it became of interest to attempt to fix the structure of the anions of these salts by means of the Raman spectra combined with the infra-red data. In what follows the carbonate ion will first be dealt with in some detail, and then the nitrate ion can be treated summarily owing to the similarity of structure of the two ions.

The raman spectra of some aromatic sulphonyl Halides

1953 ◽  
Vol 6 (2) ◽  
pp. 135 ◽  
Author(s):  
NS Ham ◽  
AN Hambly
Keyword(s):  
Raman Spectrum ◽  
Raman Spectra ◽  
Raman Band ◽  
Absorption Bands ◽  
Strong Band ◽  
Liquid Benzene ◽  
Infra Red ◽  
Group A ◽  
Methyl Benzene ◽  
Sulphonyl Fluoride

The Raman spectra of benzene-, p-chlorobenzene-, p-bromobenzene-, p-methoxybenzene-, and o-, m-, and p-toluene sulphonyl chlorides and fluorides and methylbenzene sulphonate are recorded as well as the infra-red absorption bands of liquid benzene sulphonyl chloride and fluoride between 650 and 3100 cm.-l. A frequency c. 375 cm.-1 is characteristic of the S-Cl bond in sulphonyl chlorides and a strong band at c. 1210 cm.-1 is characteristic of the sulphonyl fluoride group. A Raman band at c. 1080 cm.-l in the chlorides and c. 1095 cm.-l in the fluorides appears to be associated with aromatic sulphonyl derivatives. There is such a band at 1094 cm.-1 in the Raman spectrum of methyl benzene sulphonate.

The infra-red spectrum and crystal structure of gypsum

1956 ◽  
Vol 236 (1207) ◽  
pp. 427-445 ◽  
Keyword(s):  
Crystal Structure ◽  
Nuclear Magnetic Resonance ◽  
Raman Spectrum ◽  
Magnetic Resonance ◽  
Gaseous Phase ◽  
Deformation Mode ◽  
Water Molecules ◽  
Crystalline Field ◽  
Infra Red ◽  
Polarized Radiation

Infra-red spectra of single crystals of gypsum (CaSO 4 .2H 2 O) have been obtained between 450 and 3800 cm -1 by measurement of transmission and reflexion of plane-polarized radiation on three different crystal sections. Analysis of these observations, when combined with previous results on the Raman spectrum of gypsum, makes it possible to assign sixteen out of the eighteen internal fundamental modes of the two sulphate ions, and ten of the twelve internal fundamental modes of the four water molecules in the unit cell. Comparison of the spectra of the sulphate ions and water molecules in gypsum with those given by sulphate ions in solution and water molecules in the gaseous phase provides some information on the nature of the crystalline field. If the intensities and the dichroism of the water bands are used to verify the orientations of the water molecules in the crystal (as determined by nuclear magnetic resonance) the results obtained are anomalous. The agreement between prediction and observation is satisfactory for the deformation mode of vibration but quite unsatisfactory for the two stretching modes. Possible causes of this anomaly are discussed.

Schwingungsspektren der Clusterverbindung Nb6F15/Vibrational Spectrum of the Cluster Compound Nb6F15

1989 ◽  
Vol 44 (1) ◽  
pp. 74-78 ◽  
Author(s):  
G. Kliche ◽  
H. G. von Schnering
Keyword(s):  
Raman Spectrum ◽  
Infrared Spectrum ◽  
Vibrational Spectrum ◽  
Raman Spectra ◽  
Metal Cluster ◽  
Cluster Compound ◽  
Vibrational Modes ◽  
Infrared And Raman Spectra ◽  
Normal Coordinate ◽  
Valence Force

Abstract Infrared and Raman spectra of the metal cluster compound [Nb6F12]F3 (cubic Im3̄m; Z = 2) are reported. The three intense m odes observed in the Raman spectrum at 215. 267, and 337 cm-1 and a weak mode observed in the infrared spectrum at 287 cm-1 are assigned to the T2g, Eg, A1g, and T1u vibrational modes of the Nb6 octahedra. The assignment is supported by normal coordinate analysis and Raman measurements at 47 kbar. The valence force constants are f(Nb-Fi) = 2.04, f(Nb-Fa-a) = 1.30 and f(Nb-Nb) = 0.97 N cm-1 metal-to-metal interaction in the cluster.

The Raman and infra-red spectra of carbon suboxide

1954 ◽  
Vol 223 (1153) ◽  
pp. 251-266 ◽  
Keyword(s):  
Raman Spectrum ◽  
Raman Spectra ◽  
Malonic Acid ◽  
Mass Spectra ◽  
Linear Molecule ◽  
Molecular Symmetry ◽  
Carbon Suboxide ◽  
Photoelectric Recording ◽  
Infra Red

The infra-red and Raman spectra of carbon suboxide have been redetermined since earlier data did not permit an unequivocal decision as to the molecular symmetry. The infra-red spectrum of the gas was measured over the range 275 to 4600 cm -1 using a Perkin-Elmer spectrometer. The Raman spectrum of the liquid (at — 90° C) was investigated using a photoelectric recording spectrometer constructed in this laboratory. No trouble was experienced with decomposition of the sample. The purity of the suboxide which was prepared from malonic acid was carefully checked by following changes in the infra-red and mass spectra at various stages of the purification. In this way several bands previously attributed to the suboxide were shown to be due to impurities. Details of a normal co-ordinate treatment are given, and with its aid all the observed bands are given satisfactory assignments on the basis of a linear molecule, symmetry D ∞λ . This necessitates the postulation of one infra-red active fundamental at about 198 cm -1 . Though this lies outside the region investigated here it has recently been observed by O’Loane in the course of investigations on a series of compounds in the far infra-red.

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