Roger P. Morgan

Field ionisation kinetics: reproducibility in the determination of short lifetimes

Abstract An extremely simple but highly sensitive field ionisation (FI) source is described, together with modifications to be commercial MS-9 double focusing mass spectrometer, which allow the instrument to be used for field ionisation kinetics (FIK) measurements. It is established that the lifetimes and rate constants determined through these measurements are reproducible from laboratory to laboratory. It is suggested that the “conditioning” of the emitter of an FI source may alter the internal energy distribution P(E) of the molecular ions produced by FI. Following FI, collision-induced decompositions may make significant contributions to metastable peaks even at normal (10 μPa) analyser pressures.

Kinetics and mechanisms of the decompositions of the molecular ions of pentanal and its monomethyl-substituted homologues in the picosecond to microsecond time interval following field ionization

The kinetics of decomposition of pentanal and its monomethyl homologues, including hexanal, have been studied as a function of time following field ionisation (FI). With the aid of these results and other energetic measurements, the McLafferty rearrangement in the case of hexanal is shown to occur by a stepwise mechanism.

Kinetics and mechanisms of unimolecular gas-phase γ-hydrogen rearrangements of aliphatic aldehydes at times of the order of 10 picoseconds and longer following field ionisation

Evidence is presented that the γ-hydrogen transfer in the decomposition processes of aliphatic aldehydes referred to as McLafferty rearrangement occurs as a discrete step at times longer than ca. 20ps following field ionisation.

Unimolecular decomposition in the picosecond time-frame following field ionization of acyclic C4H8 alkenes

The kinetics of decomposition of 2H- and 13C-labelled but-1-ene and 2-methylpropene and 2H-labelled cis-but-2-ene following field ionization have been determined in the picosecond time-frame. Mechanisms are proposed to account for the major decomposition processes. Carbon randomization in the [but-1-ene]+˙ ion is a relatively slow process, and it is suggested that this fact could be due to slow vibrational relaxation.

Novel organoborane compound type from the reaction of diphenylbromoborane with di-isopropylcarbamoyl-lithium

Addition of diphenylbromoborane to di-isopropylcarbamoyl-lithium at low temperature followed by warming to ambient, and passage through silica gives 5-(di-isopropyliminio)-2,2,4,4-tetraphenyl-2,4-diborata-1-oxa-3-oxoniacyclopentane (2).