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 time-of-flight mass spectroscopy. Photoion branching ratios indicate that fragmentation to atomic ions increases at the onset of S 1s excitation and that the yield of multiply charged ions increases at the onset of S 1s excitation and again at the S 1s ionization threshold. Cleavage of the carbon–sulphur 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 fragmentation channels following S 1s→π∗ excitation and explore the fragmentation dynamics.