COLLISION DYNAMICS OF LARGE ARGON CLUSTERS

Classical trajectory calculations of collisions between Ar-1000 cluste rs are carried out to investigate the effects of relative velocity and impact parameter on energy transfer and dynamical behavior, In the ve locity range 100-1000 m/s, we conclude that the outcome of the collisi ons can be classified into a few characteristic scattering channels. W e observe coalescence, stretching separation, and shattering collision s, and each collision process dominates within distinguishable paramet er ranges. A major part of the available energy ends up in vibrational degrees of freedom, and internally hot systems cool by evaporation as well as more severe fragmentation for high-energy collisions. High ro tational excitation is observed for large impact parameter values, and the maximum rotational energy of the collision complex is concluded t o mainly determine whether a collision will result in coalescence or s tretching separation. The results are related to experimental data for collisions between large liquid droplets, and we conclude that argon clusters in the nanometer range partly resemble the larger systems. Th e boundary between coalescence and stretching separation is surprising ly well predicted by macroscopic models.