First results from gas-phase photoionisation experiments at Indus-1

A new experimental station for studying photoionisation and related processes in gaseous targets has been set up at the Indus-1 synchrotron. In the first experiment, multiple ionisation of Argon by the absorption of a single photon has been studied. Charge states as high as Ar4+ have been observed, and relative cross-sections for charge states 1-4 have been measured over a photon energy range 120-280 eV. Comparison of present measurements with existing data shows an overall agreement of the relative cross-sections of all charge states, upto the threshold of the L2-shell. Some deviations are observed at higher energies.