Generation of Multi-charged Ions in Laser-induced Ionization of Furan under Intense Nanosecond Laser Fields

The photo ionization of furan by an intense 25 ns Nd:YAG 532 nm laser has been studied by time-of-flight mass spectrometry. At the laser intensity of 1010～1011 W/cm2, multi-charged ions Can+ (n=2～4) and Ohm+ (m=2～3) appeared in the mass spectra when argon was used as the carrier gas. From the peak splitting and the numeric analysis, the most probable kinetic energies of C2+, C3+ and C4+ were confirmed to be 21、63 and 100 eV respectively, and the most probable kinetic energies of O2+ and O3+ were confirmed to be 20 and 40 eV respectively. It is proposed that the multi-charged ions come from the Coulomb explosion of furan cluster ions produced by multi photon ionization of neutral furan cluster.