Abstract

For the first time, the femtosecond real-time vibrational dynamics of the rare ^41,41K₂ isotope, excited to the electronic A¹∑⁺ state, could be selectively studied by means of time-resolved three photon ionization [1]. A vibrational period of T_A ≅ 500fs is determined. Superimposed, a beat structure with a period of 20 ps is observed. A detailed Fourier analysis reveals a strong band of three lines centered around ω(υ′, υ′ + 1) = 65.5cm^-1. A weak perturbation of the wave packet caused by spin-orbit coupling of the A and the crossing b³∏⁺ state is found. This perturbation is the reason for the fast dephasing of the initially generated wave packet within about 10 ps. The spectrogram of the real-time data (Fig. 1) neatly shows total and fractional revivals of the fundamental oscillation. Total revivals at ω(υ′, υ′ + 1) of the wave packet are observed after 20 ps and 40 ps, while fractional revivals at ω(υ′, υ′ + 2) are found for times round 10 ps and 30 ps.

© 1998 IEEE