Femtosecond vibrational dynamics of potassium dimer

Combining the femtosecond pump & probe technique with isotope-selective detection, the dynamics of the K-39,41(2) (A)(1) Sigma(u)(+) state could be investigated. The three-photon-ionization (3PI) signal was recorded over a delay time range of 220 ps. A strong oscillation around the zero-of-time dephases within 10 ps. Fourier analysis of the spectrum yields a group of frequencies settled between 63 and 68 cm(-1) which can be assigned to the energy spacings in the A state being excited by a 90-fs laser pulse. The corresponding vibrational periods could be estimated to lie between 499 and 520 fs.