Photoelectron signals arising from the Nal dynamics

We compute the photoelectron spectra using a quantum wavepacket method described in [15] with enhancements to handle the nonadiabatic interactions. Briefly, the system is expanded in terms of the three relevant electronic states 1 (Vi state), 2 (V2 state), and (ion state), as 

The photoionization matrix elements employed in these studies are obtained using high-quality wavefunctions for the bound states and photoelectron continuum. Preliminary results for this calculation were presented earlier 

For ionization of these wavepackets we choose a probe pulse with a photon energy of 4.89 eV which is just sufficient for ionization of the wavepacket on (covalent) beyond the crossing point. This pulse has a FWHM of 40 fs and its polarization can be either parallel or perpendicular to the molecular axis. 

The ion signal with the probe polarization perpendicular to the molecular axis [Fig. 5.4(b)] is significantly larger than for the parallel alignment. The shapes of these ion signals for parallel and perpendicular orientation of the polarization of probe laser to the molecular axis reflect differences in 

8 Photoelectron energy spectrum as the wavepacket moves from the ionic onto the covalent curve (third crossing). (Reprinted with permission from Y. Arasaki et al., J. Chem. Phys. 119, 7913 (2003).) 

---