Multiply ionization of benzene clusters by a nanosecond laser: Distributions of the ion charge state and the electron energy

Abstract The electron energies were measured to investigate the influences of laser intensity and wavelength on the ion charge state distribution of C q + ( q  = 2–4) when benzene clusters were irradiated by 10 9 –10 11  W/cm 2 nanosecond laser pulses. The results show that the ratios of C q + /C ( q −1)+ strongly depend on laser wavelength but slightly on laser intensity. The mean electron energy up to 100 eV was measured, which was qualitatively consisted with the ‘multiphoton ionization ignition-inverse bremsstrahlung heating-electron impact ionization’ three-stage model. The screening effects inside clusters can significantly decrease the ionization potentials of C q + and facilitate the formation of multiply charged ions especially at low laser intensity.