Cluster-assisted multiple ionization of CS 2 by intense nanosecond laser beam

Photoionization of CS 2 clusters seeded in helium is studied by time-of-flight mass spectrometry using a 25 ns, 532 nm Nd: YAG laser beam of intensity about 8×10 10 W/cm 2 . Multiply charged ions of C 2+ , S 2+ of hundreds of eV have been observed when the laser beam irradiates the most dense portion of the pulsed molecular beam. An electron re-scattering and re-colliding ionization model is proposed to explain the appearance of the multiply charged clusters under such low laser intensity.