Cluster-assisted generation of multicharged ions in nanosecond laser ionization of carbon bisulfide clusters at 1064nm

The photoionization of seeded carbon bisulfide molecular beam by a 1064 nm nanosecond Nd-YAG laser with intensities varying from 0.8\times10^11 to 5.6\times10^11 W/cm^2 have been studied by time-of-flight mass spectrometry. Multiply charged ions of S^q + (q = 2--6) and C^q + (q = 2--4) with kinetic energy of hundreds of electron volts have been observed, and there are strong experimental evidences indicating that those multicharged ions originate from the ionization of CS_2 neat clusters in the beam. An electron recolliding ionization model is proposed to explain the appearance of those multiply charged atomic ions under such low laser intensities.