Ionization and rotational wave packet dynamics of near-prolate top NO2 in an intense laser field

Abstract

We examine the ionization of NO2 in an ultrashort-pulsed near-IR intense laser field (790 nm, 100 fs, 8 × 1013 W/cm2) by recording the NO2+ yield as a function of time delay between a pump laser pulse, creating a rotational wave packet of NO2, and a probe laser pulse, ionizing NO2 to NO2+. We quantitatively interpret a periodic rotational revival structure accompanied by a fast oscillation with a period of 1.1 ps appearing in the time-delay dependence of the NO2+ yield by treating NO2 as a near-prolate top molecule. By numerical simulations of the time evolution of the rotational wave packet of NO2, we reveal that the ionization of NO2 is enhanced when the molecular b axis, corresponding to the C2 symmetry axis, is parallel to the laser polarization direction.