FEMTOSECOND TIME-RESOLVED ZERO KINETIC-ENERGY PHOTOELECTRON AND PHOTOIONIZATION SPECTROSCOPY STUDIES OF I-2 WAVEPACKET DYNAMICS

We report the application of femtosecond zero kinetic energy (ZEKE) ph otoelectron spectroscopy and photoionization to the study of bound wav epacket motion in the electronic B state of iodine by a [1 + 2] multip hoton process. The experimental approach is described in detail. Compa risons of ZEKE photoelectron detection with ion detection are made. Th e pump wavelength was fixed at 580 nm whereas the probe wavelength was tuned from 350 to 300 nm, Wavepacket motion in the B state with the f undamental vibrational period of 340 fs was observed, as well as wavep acket dephasing and rephasing, Differences in the modulation depths an d Fourier transform power spectra were observed, The phase shifts (tim e offset from Delta t = 0) and modulation patterns varied as the locat ion of the Condon point for the probe step changed upon tuning the pro be wavelength, Higher-order wavepacket fractional revivals were observ ed in time-windowed Fourier transform power spectra.