Photofragmentation of OCS at the S 1s edge

The photofragmentation of carbonyl sulphide following sulphur 1s excitation has been investigated using monochromated synchrotron radiation and ion ti me-of-flight mass spectroscopy. Photoion branching ratios indicate that fra gmentation to atomic ions increases at the onset of S 1s excitation and tha t the yield of multiply charged ions increases at the onset of S 1s excitat ion and again at the S 1s ionization threshold. Cleavage of the carbon-sulp hur bond is favoured over cleavage of the oxygen-carbon bond both above and below the sulphur 1s ionization threshold. The multi-coincident detection of up to three photoions per ionization event is used to identify the fragm entation channels following S 1s-->pi* excitation and explore the fragmenta tion dynamics. (C) 1999 Elsevier Science B.V. All rights reserved.