Size and wavelength dependent photoionisation of xenon clusters

Size and wavelength dependent photoionisation studies have been carried out on xenon clusters (Xen) using nanosecond long gigawatt intensity laser pulses. The ionic species (Xe+, Xe2+, … Xe10+) were characterized by time-of flight mass spectrometry. It is observed that higher the irradiation wavelength, higher is the maximum observed charge state of xenon ion. Clusters of 〈Xe17〉 on irradiation with 532 nm pulses yielded only singly charged ions (Xe+, … Xe4+) whereas 〈Xe50〉 produced multiply charged Xe ions (Xen+, n = 1–10). With increase in cluster size, kinetic energy of multiply charged xenon ions was found to increase, while the threshold laser intensity for inducing multiple ionisation within the cluster decreases from 9 × 109 W/cm2 for 〈Xe50〉 to 3 × 109 W/cm2 for 〈Xe11400〉.