Trevor R. Gilson

Vibrational structure in the laser excitation spectrum of nickel dichloride at 360 nm

Abstract Nickel dichloride has been formed “cold” in the vapor phase by heating the solid to about 750°C, entraining the vapor in a high pressure of argon and expanding it supersonically through a small hole into a vacuum chamber. The laser excitation spectrum of the sample prepared in this way has been recorded in the region of 360 nm. Under these conditions, it is possible to resolve both vibrational and rotational fine structure. The same spectrum was recorded when carbon tetrachloride vapor was passed over the hot metal and expanded through the nozzle. Some “hot” bands have been identified by dispersing the fluorescence with a small monochromator. Virtually no chlorine isotope structure could be identified, even when isotopically enriched samples were used. A partial analysis of the vibrational structure has been achieved in which several progressions in the symmetric stretching vibration have been identified. These progressions are consistent with a value for v 1 of 360 cm −1 for the lower electronic state and 345 cm −1 for the upper electronic state. The complications in the observed spectrum may be caused by two or more upper electronic states being involved in the band system.

the dispersed fluorescence of nickel dichloride under molecular beam conditions: A determination of ground-state vibrational intervals

Abstract Cold nickel dichloride, NiCl2, has been produced in a supersonic beam by expansion of its vapour through a heated nozzle. Fluorescence has been excited with the 364 nm line of an argon ion laser and dispersed to reveal extensive vibrational progressions of 357 cm−1 at spacings of 177, 401 and 1026 cm−1 from the laser frequency. These have been assigned to the symmetric stretching frequency (ν1 = 357 cm−1), twice the bending frequency (2ν2=177 cm−1) and twice the antisymmetric stretching frequency (2ν3 = 1026 cm−1). No definite assignment for the 401 cm−1 interval can be suggested.

Characterisation of ortho- and meta-boric acids in the vapour phase

Vibrational spectroscopy in the vapour phase has shown metaboric acid cyclic trimer in equilibrium with monomeric orthoboric acid and water. An approximately equal amount of boron (1 : 3 mole ratio) is present as (HBO2)3 and as H3BO3, at 350 °C and a few atmospheres total (water and boric acid) pressure; a condensed phase of widely variable composition is also present. Proportionately very much less trimer is present at the lowest temperatures (just over 100 °C for IR work).

Mass spectra and vibrational spectra of ‘TeCl2Br2’. The vibrational spectrum of tellurium tetrachloride

Mass spectrometric studies show the presence of more than one compound in the vapour above TeCl2Br2. In agreement with this observation, at least five ‘stretching modes’ are found from Raman and i.r. studies of ‘TeCl2Br2’ in the gas-phase. A previous assignment of stereochemistry on the basis of the Raman spectrum of TeCl2Br2 cannot be confirmed. Matrix i.r. and Raman spectra, and gas-phase i.r. spectra (using an i.r. cell with sealed-in silicon windows), are reported for tellurium tetrachloride. The results do not disagree with a C2ν, formulation for this molecule.

Gas phase Raman spectrum of CdI2 and of a 1:8 mol ratio of CsI-CdI2

Abstract The Raman spectrum of gaseous CdI 2 shows a strong polarized band at 153 cm −1 which is the symmetric stretching vibration (ν 1 ) of this molecule. No detectable change could be found in the presence of CsI even at 1030°C and a total pressure of the order of five atmospheres.

Matrix isolation studies of monomeric boron trisulphide

The i.r. spectrum of diboron trisulphide isolated in argon and nitrogen matrices is reported. The use of partial isotopic substitution (10B/11B and 32S/34S) enables the observed bands to be assigned to in-phase and out-of-phase vibrations of two –BS residues in a non-linear arrangement. This, coupled with mass spectrometric evidence and the assumption of linear SB–S linkages, show the shape of monomeric B2S3 to be based on a planar C2v molecule with a BSB bond angle of ca. 120°.

Coherent Antistokes Raman Spectroscopy In Sooty Diffusion Flames

The main reason for doing spectroscopy in a sooty diffusion flame, rather than in a well characterized and controlled environment, is that such a flame is thought to be a good model for the early stages of many jet combustors where particle concentrations, temperature, and possibly turbulence are likely to be similar. However, there are important differences. For example, the total pressure in a practical combustor is several atmospheres and it is pressure rather than an excess of fuel which causes soot formation in that case.