A study of some atmospherically important reactions with U.V. photoelectron spectroscopy

A number of reactions relevant to atmospheric chemistry have been studied by photoelectron spectroscopy (PES) in this worlc. PES studies of the Ci+DI^S (dimethyl sulphide), CI+DMDS (dimethyl disulphide), CI2+DMS and CI2+DMDS reactions were performed for different reaction times at low pressure (<^1 x 10'^ mbar in the ionization cell) and 298 K. It was found that the reaction CI2+DMS proceeds through a 1:1 complex HO: CH3SCH2CI which decays later to CH3SCH2CI+HCI; DMDS reacts with CI2 directly to form CH3SCI with no complex formation. Both atom-molecule reactions, DMS+CI and DMDS+CI proceed through two + CH3SCH2. channels. For the DMS reaction the first channel is CI + DMS HCI Further reaction of CH3SCH2 with CI2 gives HCI + CH3 + HCICS (la). The second channel is CI + DMS CH3SCI + CH3 (lb). For the CI+DI^DS reaction the first channel is CI + DMDS HCI + CH3SSCH2. Further reaction of CH3SSCH2 with CI2 gives HCI + HCICS + CH3S (CH3S is short-lived and it forms either CH3SH on reaction with DMS, or CH3CI on reaction with CI2) (2a). The second channel is CI + DMDS CH3SCI + CH3S. In studying these reactions, chlorine atoms were produced from two different sources: SiC^and CI2 microwave discharges. The final reaction studied was ethylene plus ozone. The main product of this reaction is formaldehyde but the main interest in this reaction is the role of one of its intermediates, the Criegee intermediate (alkene peroxy radical). The observation of O2 alAg from the reaction is consistent with the presence of the Criegee intermediate in its singlet state.

University of Southampton

De Frutos Del Rio, Santiago

362eaeac-035b-4a77-929f-2f7090f9c421

2002

De Frutos Del Rio, Santiago

362eaeac-035b-4a77-929f-2f7090f9c421

De Frutos Del Rio, Santiago (2002) A study of some atmospherically important reactions with U.V. photoelectron spectroscopy. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)