Metastable fragmentation and photodissociation of sulfur-containing molecular cluster ions

CHED 1003

Luke A. Erickson, hales@hendrix.edu and David A. Hales, hales@hendrix.edu. Department of Chemistry, Hendrix College, 1600 Washington Avenue, Conway, AR 72032
Sulfur-containing compounds are investigated for potential use in forming stratospheric aerosol particles intended to reflect sunlight and slow global warming. Clusters of dimethyl sulfide, dimethyl disulfide, and thiophene are ionized with two photons of 248 or 193 nm light in a time-of-flight mass spectrometer. Metastable fragmentation of mass-selected cluster ions shows that these cluster ions eliminate both whole molecules and various molecular fragments. Photofragmentation (1064, 532, 355 nm) enhances some of these dissociation channels and also introduces others. Doping clusters of dimethyl sulfide and dimethyl disulfide with thiophene can significantly increase photoionization efficiency. Mixed cluster studies with water and oxygen are attempted in search of evidence for the formation of SOn+ (n = 2 or 3) ions, which could function as precursors to atmospheric sulfate aerosol particles.