Raman spectrum of acetonitrile

Raman spectrum of acetonitrile has been re-examined. 19 Raman lines have been recorded which include all the eight fundamental modes, three octaves and six summations. The fundamental mode ν7 which has not been recorded before appears very weakly in the Raman spectrum.

Raman spectrum of ethyl chloroacetate

The Raman spectrum of ethyl chloroacetate has been studied at 13° C., 28° C. and 78° C. The carbonyl frequency was found to be split up into two due to the presence of rotational isomers. The higher frequency line due to thecis isomer was found to decrease in intensity with temperature. It appears that the gauche isomer will predominate in the vapour state. Altogether thirty-eight Raman lines have been recorded. Reasonable assignments for the observed Raman lines were made in comparison with ethyl acetate spectrum.

The emission spectrum of bismuth monofluoride BiF—‘A’ system

The observation of (A-X) system of BiF has been extended up to λ 5316 and twenty new bands belonging to this system have been recorded. The band heads could be represented by the following equation: {Mathematical expression} Seven other faint bands in the region λ 5316-5492 have also been reported, which, however, could not be classified. By our analysis of the present data and from known thermochemical data it has been deduced that the ground state dissociation energy is, in all probability, around 20000 cm.-1 (∼2·5 ev.) and that the dissociation products are the normal Bi and F atoms. The dissociation energy of the upper state and the correlation rules have been used to show that the dissociation products in the upper state are very likely to be Bi atom in the excited state2D3/2 and F atom in its ground state (2P3/2).

Raman spectrum of hydroxylamine hydrochloride (NH3OH.Cl)

The Raman spectrum of hydroxylamine hydrochloride (NH3OH.Cl) in the form of a single crystal has been photographed usingλ 2536·5 excitation. 32 Raman lines with frequency shifts 40, 57, 78, 88, 111, 125, 135, 156, 187, 217, 250, 330, 550, 575, 1004, 1168, 1204, 1470, 1496, 1565, 1590, 1979, 2636, 2710, 2750, 2789, 2926, 2970, 3000, 3050, 3141 and 3220 cm.−1 have been recorded. Of these, the first 8 low-frequency lines belong to the external oscillation, while the four lines at 187, 217, 250 and 330 cm.−1 should be attributed to the vibrations of the hydrogen bond valence vibrations. The remaining Raman lines have been assigned to the vibrations of the NH3OH ion. The O-H and N-H stretching vibrations are very much influenced by the presence of the hydrogen bonds in the crystal.

Raman spectrum of diglycine barium chloride monohydrate

The Raman spectrum of diglycine barium chloride monohydrate in the single crystal form has been recorded using λ 2536·5 excitation. 43 Raman lines (9 lattice and 34 internal) have been recorded. Satisfactory assignments have been given for most of the observed Raman lines. It is concluded from a comparison of the Raman spectrum of this compound with those of glycine and of other addition compounds of glycine, that the glycine unit exists in the zwitterion form in the structure of diglycine barium chloride monohydrate.

Raman spectrum of C-deuteratedγ-glycine (NH 3+ CD2COO−)

The Raman spectrum of C-deuterated γ-glycine (NH3+CD2COO-) in the crystal powder form was taken using λ 2536·5 excitation. 26 Raman lines were recorded. Of these, eight lines are attributed to the external oscillations and eighteen Raman lines to the internal oscillations. Proper assignments are given to the observed frequencies.

Raman spectrum of triglycine selenate (G3Se), [(NH2CH2COOH)3 H2SeO4]

The Raman spectrum of a single crystal of triglycine selenate G3Se which is ferroelectric below 22° C. has been photographed using λ 2537 excitation. 42 Raman lines have been recorded of which 6 belong to the lattice spectrum, 3 are due to NH...O oscillations and the remaining 33 are due to internal oscillations of the ions of glycine and SeO4--. There is a close similarity between the spectrum of triglycine selenate and the spectrum of its isomorph, triglycine sulphate, the frequency shifts due to the SO4-- ion being replaced by the frequency shifts due to the SeO4-- ion. The existence of glycine in the zwitterion form in the structure of G3Se is substantiated by the appearance in the Raman spectrum of lines which are attributable to NH3+ groups and COO- groups. The appearance of the additional C-H line at 2982 cm.-1 in the spectrum of triglycine selenate which is absent in the spectrum of α-glycine indicates the existence of planar monoprotonated glycine also in the structure, as indicated by X-ray studies.

Raman spectrum of sodium iodide

Raman spectrum of a single crystal of sodium iodide has been recorded for the first time using lambda 2537 excitation. The general features of the spectrum are discussed in the light of the existing theories on the dynamics of the alkali halides. The authors wish to thank Professor D.Y.Phadke of the Tata Institute of Fundamental Research, Bombay, for presenting the crystal of Nal used in the present investigation.

Raman spectrum of lanthanum ethyl sulphate nonahydrate

Raman spectrum of a single crystal of lanthanum ethyl sulphate has been recorded for the first time using the λ 2537 radiation Forty-one lines have been identified out of which eight belong to the lattice oscillations, seven to the internal vibrations of the water molecule and the remaining twenty-six to the internal vibrations of the ethyl sulphate group. The Raman spectrum of ethyl sulphate (liquid) has also been recorded using the λ 4358 excitation and is compared with the spectrum of lanthanum ethyl sulphate. Thirty Raman lines could be identified in the spectrum of ethyl sulphate, of which fourteen are recorded for the first time. Probable assignments of the observed frequencies are also given. The sulphate group is found to have O-SO3 structure in lanthanum ethyl sulphate, while it has a co-ordination {Mathematical expression} in ethyl sulphate.

The Raman spectrum of cyclohexanol

The Raman spectrum of cyclohexanol has been studied in detail in the liquid state at 30° C. and at about 68° C. and in the solid state at about 13° C. The O-H stretching frequency of cyclohexanol has been found to extend from 3106-3571 cm.-1 in the liquid state at 30° C. and from 3204-3652 cm.-1 at 68° C. The 38 lines recorded in the present investigation have been following frequency shifts: 342, 408, 458, 478, 555, 653, 789, 834, 843, 863, 887, 920, 966, 978, 1024, 1047, 1070, 1139, 1173, 1184, 1210, 1235, 1252, 1301, 1329, 1346, 1362, 1438, 1448, 1464, 2660, 2684, 2710, 2854, 2896, 2925, 2940, 3106 to 3511 (band). Those lines which are italicized are the additional lines observed for the first time. The Raman lines at 966 cm.-1 and 1070 cm.-1 have been assigned to C-OH stretching vibrations of the axial and equatorial isomers. The ratio of the integrated intensity of the 1070 cm.-1 line to the 966 cm.-1 gave the equilibrium constant K as 2·896 at 30° C. and as 2·66 at 68° C. Knowing K, the free energy different Δ F was calculated and it was found to be 0·64 Kcal./mole at 30° C. and 0·66 Kcal./mole at about 68° C. Reasonable assignment has been made for most of the observed Raman lines.

The Raman spectrum of boric acid

The Raman spectrum of crystalline boric acid is recorded using mercuryλ2537 excitation. Fifteen Raman lines, three of them belonging to the lattice spectrum, are reported. Satisfactory assignments of all the observed Raman frequencies are made using the available X-ray crystal structure data. From the presence of a new high frequency Raman band at about 3420 cm.−1 it is suggested that there might be a small number of long, weak O-H....O hydrogen bonds in the crystal, in addition to the hydrogen bonds of moderate strength reported from X-ray diffraction data.

The emission spectrum of bismuth bromide (BiBr)-"A" system

The emission spectrum of bismuth monobromide has been investigated and a vibrational analysis of the A→X system has been made. About 286 bands were recorded in the region λλ 4595–6063 and the isotope effect due to Br79 and Br81 was observed in about 87 bands. A value of 2·74 ev. for the dissociation energy of the excited state has been obtained and arguments have been given to show that the dissociation products in the excited state are Bi(4S3/2) and Br(2P3/2) and that those of the ground state are most probably Bi (4S3/2) and Br (2P1/2) atoms.

Raman spectrum of l-asparagine monohydrate

The Raman spectrum of l-asparagine monohydrate in the form of a single crystal has been recorded for the first time. λ 2537 excitation has been used. Fifty-three Raman frequency shifts have been recorded. They are grouped as follows: Eight Raman lines coming under the lattice spectrum, three Raman lines arising from low-frequency vibrations of the hydrogen bonds and the remaining forty-two arising from the internal oscillations of the asparagine molecule. Appropriate assignments have been given for the observed Raman lines

Raman spectrum of strontium titanate

The Raman spectrum of strontium titanate has been recorded using λ 4358 of mercury as exciter. The observed spectrum consists of 7 Raman lines, one of which is of low frequency, as expected from the recent theory of Cochran. 6 of these Raman lines have been interpreted as the first order spectrum arising from a small deviation of the cubic strontium titanate from its idealized symmetry. It has been shown that one normal mode of SrTiO3 neglected by J.T. Last, will be really active in infrared absorption in the region of 440 cm-1 and that it has to be taken into account in the interpretation of the infrared spectra of titanates. The four vibrational modes of the unit cell of SrTiO3 correspond to frequencies of 90, 335, 441 and 620 cm-1 observed in Raman effect. The large width of the Raman lines and the additional lines at 256 cm-1 and 726 cm-1 have been attributed to a splitting of the longitudinal and transverse optical modes. With the observed frequencies it has been found possible to account for in a satisfactory manner the specific heat of SrTiO3 in the range 54·84° K to 1800° K.