Femtosecond vibrational wavepacket spectroscopy in the electronic ground state of K2

Vibrational wavepacket propagation in the electronic ground state |X〉 of supersonic jet cooled potassium dimers was investigated with a femtosecond pump–probe experiment. The wavepackets were generated by resonance enhanced stimulated Raman scattering into v′′X=5 and interrogated by a time delayed three photon ionization process. The choice of the wavelength of the probe photons enabled a pure detection of ground state wavepacket dynamics. Fourier analysis of the wavepacket oscillation with a period of 375 fs reveals a one color stimulated emission pumped component around 92 cm−1 and a stimulated Raman pumped component around 88 cm−1.