Energy transfer of highly vibrationally excited molecules studied by crossed molecular beam/time-sliced velocity map ion imaging

Abstract

Energy transfer of highly vibrationally excited molecules has been studied extensively under bulk conditions in the past 40 years. On the other hand, in 1973 Fisk and co-workers reported the first experimental results of collisional energy transfer of highly vibrationally excited KBr using cross-molecular beams. Surprisingly, it is the only crossed molecular beam experiment about the energy transfer of highly vibrationally excited molecules. No other similar crossed molecular beam experiments have been reported in the following four decades. Recently we have studied the energy transfer of highly vibrationally excited molecules using crossed molecular beams/time-of-flight mass spectrometer in combination with time-sliced velocity map ion imaging techniques. Energy transfer probability density functions were accurately obtained and details of energy transfer mechanisms were evidenced from the cross-molecular beam scatterings. This paper reviews our recent work of energy transfer of highly vibrationally excited molecules. The effects of long-lived complex, initial translational energy, initial rotational temperature, vibrational motions, alkylation, attractive potential and electronic state on the energy transfer and supercollisions were discussed, and comparisons to theoretical calculations and experiments conducted under bulk conditions were made.

Keywords:

• energy transfer
• highly vibrationally excited molecules
• supercollisions
• crossed molecular beams
• velocity map ion imaging

Acknowledgements

CKN appreciates Prof. George W. Flynn for the introduction and guidance into this research field, and helpful discussion with Prof. Yuan T. Lee, I. Oref, Kopin Liu J. Lim. This work was supported by the National Council, Taiwan, under contract NSC100-2113 -M-001-026-MY3.