DISSOCIATIVE SINGLE, DOUBLE, AND TRIPLE PHOTOIONIZATION OF OCS IN THE REGION H-UPSILON = 20-100 EV STUDIED BY MASS-SPECTROMETRY AND THE PHOTOION PHOTOION COINCIDENCE METHOD

The photoionization of OCS in the photon energy region of 20-100 eV has been studied using time-of-flight (TOF) mass spectrometry and the photoion-photoion coincidence (PIPICO) method together with linearly polarized synchrotron radiation. The TOF mass spectrometer facilitates relatively efficient extraction of energetic ions, which is essential for quantitative measurements. The double photoionization threshold is measured to be 31.0 +/- 0.5 eV. Photoion branching ratios are reported for singly and doubly charged ions which are measured parallel and perpendicular to the electric vector of the incident photon beam. It is found that the ion intensities in the TOF mass spectra are affected by anisotropic angular distributions of photoelectrons relevant to the production of the OCS+, S+, and CS+ ions. PIPICO branching ratios are also reported, dissociation of OCS3+ into OC+ + S2+ being observed in the, PIPICO spectra with a threshold at 63 +/- 3 eV.