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The matrix isolation-IR and time-of-flight mass spectrometric study of metal-containing chemical intermediates formed in a DC electrical discharge

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posted on 2014-12-15, 10:35 authored by Barry James. Pollard
A new instrument has been designed and constructed to combine matrix isolation infra-red spectroscopy with an electrical discharge supersonic nozzle. The principal aim of this apparatus was to study reactive metal-containing molecules by fragmentation and/or cathode sputtering inside the nozzle.;The discharge of chromium and molybdenum hexacarbonyls has been studied by isolating the products in argon matrices. IR spectroscopy was used to identify Cr(CO)n (n = 5,4) and Mo(CO)m (m = 5-3), the first time these metal carbonyls have been produced by discharge fragmentation.;The discharge fragmentation of the group 13 metal trialkyls, A1(CH3)3 and Ga(CH3)3 has been investigated. For trimethylaluminium (TMA), which is mainly dimeric at room temperature, the major product was monomeric TMA. No new metal-containing intermediates were identified due to the congested nature of the IR spectra. However, in comparable experiments on trimethylgallium (TMG) which is a monomer under normal conditions, monomethylgallium, GaCH3, has been observed. There have been no previous spectroscopic reports of this molecule. The spectra were assigned with the aid of isotopic substitution studies, as well as ab initio calculations.;The final chapter details other tests carried out in the commissioning of the experiment. These have included tests carried out to ascertain the extent of fragmentation in the discharge, the sputtering of metal atoms in the discharge, and the introduction of a time-of-flight spectrometer for rapid optimisation of the discharge conditions.

History

Date of award

1999-01-01

Author affiliation

Chemistry

Awarding institution

University of Leicester

Qualification level

  • Doctoral

Qualification name

  • PhD

Language

en

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