THE INFLUENCE OF THE IONIZATION-POTENTIAL ON THE SIMULATED ION SIGNALFROM FEMTOSECOND PUMP-PROBE EXPERIMENTS

Femtosecond pump-probe experiments involving pseudorotational motion o n the B state of the sodium trimer are simulated using time-dependent wavepacket calculations. The calculations are carried out in two dimen sions, corresponding to the radial and angular pseudorotation modes. T he pump and probe lasers are modelled using time-dependent first-order perturbation theory. The ion signal is simulated using two different values of the ionisation potential: the first, 32240 cm(-1), is close to an older experimental value; the second, 31363 cm(-1), was recently obtained from ZEKE spectra. The relative intensities of different pea ks depend strongly on the value of the ionisation potential used. The ion signal calculated using the more recent value for the ionisation p otential shows closer agreement with the signal found in the experimen ts.