Ultrafast Time-resolved Polarization-dependent Investigations on the Dynamics in the A ˜ 2 B2 State of NO2 Molecules.

ABSTRACT

We perform time-resolved polarization-dependent study on ultrafast dynamics in the A ˜ 2 B2 state of NO2 . A linearly-polarized 400 nm femtosecond laser is used to resonantly pump NO2 to its first excited state A ˜ 2 B2 , and the time-dependent ionic yields produced via strong field ionization at 800 nm are measured under different laser polarizations. The yield ratios measured with the lasers perpendicular and parallel to each other first decrease and then increases as the wave packet evolves on the excited state, with a minimum ratio at 180 fs delay time, which can be attributed to the evolution time in the A ˜ 2 B2 state. The behavior of the time-resolved ionization in elliptically polarized laser field is also investigated and discussed.