P. Rosendo-francisco et al., Ultrafast fragmentation and vibrational dynamics of triatomic hetero- and homonuclear alkali metal clusters, J CHIN CHEM, 47(4A), 2000, pp. 705-708
The one-color femtosecond pump and probe spectroscopical technique was empl
oyed to study the fragmentation kinetics and vibration dynamics of the diss
ociative excited states of alkali trimer clusters K2Na, K-3 and Na2K locate
d in the spectral region between 730 and 840 MI. The electronically excited
states were populated by a pump pulse via one-photon absorption. The tempo
ral evolution of the excited state was then monitored by ionizing the parti
cle at a variable delay with a two photon transition. The lifetimes of the
predissociated excited states strongly depend on the excitation wavelengths
: 2.8-5.1 ps for K2Na, 7.5-9.8 ps for K-3, and 2.5-5.8 ps for Na2K. Further
more, the dominant fragmentation channels were identified as well. In the c
ase of the Na2K trimer a clear wavepacket dynamics with an oscillation peri
od of about 490 fs was observed at an excitation wavelength of 770 nm. In t
he case of the K-3 and K2Na trimers, no pronounced oscillatory ion signal i
ndicative of a vibrational dynamics was observed at the applied wavelength
region.