Near-dissociation studies of diatomic cluster ions

Pyne, Christopher Hugh (1994) Near-dissociation studies of diatomic cluster ions. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

Microwave transitions involving vibration-rotation levels lying less than 10 cm^-1 (300 GHz) from the lowest dissociation limit have been recorded in the diatomic cluster ions He₂⁺ and He Kr⁺, and in the hydrogenic ion HD⁺. Indirect detection methods have been developed concentrating upon electric field induced dissociation of an ion beam; the ion fragments formed in a region of strong electric field were monitored for any change in intensity induced by a spectroscopic transition.

Two transitions are reported for HD⁺; their frequencies were found to agree with current nonadiabatic theory to within 2 MHz. Both of the transitions were split into multiple lines by nuclear hyperfine effects; the experimentally measured hyperfine splittings were found to differ from the calculated values by less than 0.2 MHz. Seven microwave transitions were observed in He₂⁺, all of which have been assigned using a combination of further experiments and ab-initio calculations, with an average error of 46 MHz. Results are also presented for He⁸⁴Kr⁺ where seven transitions have been recorded and assigned experimentally using the magnetic Zeeman effect; a further fourteen absorptions, detected using a variety of experimental techniques, are presented.

An experimental investigation of the pressure dependency of the number of fragments observed from a parent ion undergoing electric field dissociation has been undertaken. The results predict candidate molecules for future microwave spectroscopic studies. (DX183,753)

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