Photoionization of NO molecule in two-color femtosecond pulse laser fields

The influence of molecular alignment and orientation in the ground state and excited state on the resonance-enhanced multi-photon ionization dynamics

We explore the influence of molecular alignment and orientation in the ground and excited states on the ionization probability, photoelectron angular distribution (PAD), energy-resolved photoelectron energy spectrum (PES) and two-dimensional momentum spectrum in the resonance-enhanced multiphoton ionization (REMPI) process. The calculated results for the LiH molecule show that molecular pre-alignment and -orientation have different effects on molecular photoionization. The ionization probability and energy-resolved photoelectron spectrum are associated with molecular pre-alignment. The angular distribution of photoelectrons and angular distribution of the momentum spectra are closely dependent on molecular pre-orientation. The ionization probability is also related to the center time and overlap area of the pump and probe pulses.

The photoionization dynamics based on molecular pre-orientation

We study theoretically the photoionization dynamics of pre-oriented NaK molecule. Firstly, a THz laser pulse is utilized to orient the ground state molecule. And then the pump and probe laser pulses are used to excite and ionize the molecule, respectively. We study the influence of molecular orientation duration and degree on the ionization probability, angle-resolved photoelectron spectrum and photoelectron angular distribution (PAD). It is shown that we could obtain more stable ionization signal and PAD when the molecules are ionized in molecular orientation duration. We could increase the ionization probability and obtain more concentrated ionization signal and photoelectron distribution by increasing the orientation degree in the ground state. Moreover, we discuss the splitting pattern in the angle-resolved photoelectron spectrum.

ABOVE THRESHOLD IONIZATION OF POLAR NaK MOLECULES DRIVEN BY FEW-CYCLE LASER PULSE

We investigate theoretically the above-threshold ionization (ATI) of the polar NaK molecule exposed in few-cycle laser field by numerically solving the time-dependent Schrödinger equation including the vibrational and rotational degrees of freedom. The left and right ATI spectra are calculated by integrating the ionization continuum wave function over the left and the right half spheres along the laser polarization. We find that the left and right ATI spectra are asymmetric, and this asymmetry depends strongly on the molecular orientation and the carrier-envelope phase (CEP) of the laser pulse. Moreover, we also perform the calculation for different initially rotational states to study the effect of rotational temperature on the ATI dynamics.

THE EFFECT OF THE COUPLING BETWEEN VALENCE STATE B2Π AND RYDBERG STATE C2Π ON THE ABSORPTION SPECTRUM OF THE NO MOLECULE

The effect of the coupling between the valence state B 2Π and the Rydberg state C 2Π on the absorption spectrum of the NO molecule is studied by using the quantum wave packet dynamics method. The results show that the coupling between the valence state B 2Π and the Rydberg state C 2Π affects the C 2Π ← X 2Π absorption spectrum both in the intensity and on the location of spectrum peaks. The dynamics of the wave packet of the excited states is also described. One part of the wave packet evolves on the Rydberg state C 2Π and the other is trapped in the valence state B 2Π.