Photoionization mechanisms for Cr(CO)₆ using high intensity laser pulses in the near-IR

High intensity (i.e. 10¹³ W/cm²) picosecond and femtosecond laser pulses are utilized to study possible photoionization mechanisms of Cr(CO)₆. This work represents the first example of excitation of a metal carbonyl with 800 nm photons where the ionization of intact molecular species dominates photofragmentation channels. With picosecond pulse excitation, however, attenuation of the laser power appears to induce a higher degree of fragmentation. The data can best be interpreted assuming two distinct photoionization mechanisms where MPI dominates at low laser powers and a transition occurs to barrier suppression ionization as the laser power is increased.