@article{HartmannHeidenreichPittneretal.1998, author = {Hartmann, Michael and Heidenreich, Andreas and Pittner, Jiř{\i}́ and Bonačić-Kouteck{\´y}, Vlasta and Jortner, Joshua}, title = {Ultrafast Dynamics of Small Clusters on the Time Scale of Nuclear Motion}, series = {The Journal of Physical Chemistry A}, volume = {102}, journal = {The Journal of Physical Chemistry A}, number = {23}, pages = {4069 -- 4074}, year = {1998}, abstract = {We present a theoretical study of the multistate dynamics of the Ag3-/Ag3/Ag3+ system on the time scale of nuclear motion, as explored by femtosecond pump-probe negative ion-to neutral-to positive ion (NENEPO) spectroscopy. The dynamics of the Ag3 cluster initiated from its linear transition state involves configurational relaxation, intracluster collision, and onset of IVR, resonant and dissipative IVR and vibrational equilibration, whose time scales were determined. Our analysis reveals that theory is essential for the elucidation of the rich dynamic information regarding geometrical change, completion of IVR, and vibrational coherence effects in the NENEPO femtosecond signals.}, language = {en} } @article{HartmannPittnerBonačićKouteckyetal.1998, author = {Hartmann, Michael and Pittner, Jiř{\i}́ and Bonačić-Kouteck{\´y}, Vlasta and Heidenreich, Andreas and Jortner, Joshua}, title = {Theoretical exploration of femtosecond multi-state nuclear dynamics of small clusters}, series = {The Journal of Chemical Physics}, volume = {108}, journal = {The Journal of Chemical Physics}, number = {8}, pages = {3096 -- 3113}, year = {1998}, abstract = {We investigate ultrafast multi-state nuclear dynamics in a triatomic cluster. In particular, we explore how the intracluster nuclear dynamics of the Ag-3/Ag3/Ag+3 system is reflected in the femtosecond pump-probe negative ion-to neutral-to positive ion (NENEPO) signals. The nuclear dynamics is based on classical trajectories on the ground electronic adiabatic state potential hypersurfaces obtained from accurate ab initio quantum chemistry calculations. The nuclear dynamics of Ag3 initiated from the linear transition state involves distinct sequential processes of configurational relaxation to the triangular configuration, intracluster collisions, and the onset of IVR, resonant, and dissipative IVR, and vibrational equilibration. We determined the timescales for these processes and discussed their dependence on the initial cluster temperature. The Wigner representation of the density matrix was utilized to simulate the NENEPO-zero kinetic energy (NENEPO-ZEKE) signal and the total (integrated over the photoelectron energy) NENEPO signal. We show how geometrical change, completion of IVR and vibrational coherenceeffects can be identified in the NENEPO signals. A comparison of the calculated NENEPO signals with the available experimental data is presented.}, language = {en} }