Quantum wavepacket dynamics for time-resolved photoelectron spectroscopy of the NO2 conical intersection

Quantum wavepacket dynamics at the X2A1/A2B2 conical intersection of NO2 molecule following a femtosecond pump pulse is computed, and subsequent probing of the dynamics with time-resolved femtosecond photoelectron spectroscopy is investigated theoretically. Diabatic representation of the ground and first excited state potential energy surfaces are constructed, and is used in time propagation of the vibrational wave function through pump and probe pulses in three dimensions. The Hamiltonian explicitly includes the pump interaction between the neutral states and probe interaction between the neutral and (discretized) ion continuum. Constant ionization matrix elements are used in this study. The computed photoelectron kinetic energy spectra are seen to reflect ultrafast wavepacket motion through the conical intersection region at early times.