Laser spectroscopy of metal-containing intermediates prepared using electrical discharge methods

• Main Author: Bezant, Andrew John
• Published: University of Leicester 1997
• Subjects: 547
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.696272

Metal-containing reaction intermediates, especially simple organometallics, have been subject to relatively few spectroscopic studies to date. This thesis describes experimental techniques which can be used to study such molecules and presents results from several examples. In particular, the emphasis is on organometallic free radicals. A laser-induced fluorescence (LIF) spectroscopic study has been carried out on monoalkyl zinc free radicals. These were prepared in a supersonic jet from dialkyl zinc precursors using a pulsed electrical discharge nozzle. This method was tested on ZnCH3 and shown be successful. The study was then switched to ZnC2H5, and the first gas-phase spectrum of this molecule has been recorded. The jet-cooled spectrum shows considerable vibrational structure, some of which has been assigned. A new pulsed electrical discharge nozzle has been developed for producing metal-containing intermediates via metal atom reactions. This unique nozzle consists of two channels, which eventually merge into one. One channel is used for metal atom sputtering, while the other supplies an organic or organometallic reagent. The operational feasibility of this nozzle has been tested on several well-known species including PtC, ZnCH3, and CdCH3. The cadmium monoethyl radical was made using the dual-channel discharge nozzle, from the reaction of sputtered cadmium atoms and diethyl zinc precursor. Observation of this intermediate, using LIF spectroscopy, represents the first reported work on this molecule. A time-of-flight mass spectrometer has been constructed for REMPI spectroscopic studies. It is planned to be used for the mass-selective spectroscopic investigation of metal-containing intermediates from complex mixtures, as typically pertain in laser ablation or pulsed discharge studies.