Energy Transfer of Highly Vibrationally Excited Molecules
Date Issued
2009
Date
2009
Author(s)
Hsu, Hsu-Chen
Abstract
The energy transfer of highly vibrationally excited molecules plays an important role in many chemical processes. A number of experimental and theoretical works have focused on the energy transfer dynamics of highly vibrationally excited molecules. In this thesis, the methylation effects in the energy transfer between Kr atoms and highly vibrationally excited 2-methylnaphthalene in the triplet state were investigated using crossed-beam/time-sliced velocity-map ion imaging technique at a translational collision energy of ~520 cm-1. Comparison of the energy transfer between naphthalene and 2-methylnaphthalene shows that the difference in total collisional cross sections and the difference in energy transfer probability density functions are small. The ratio of the total cross sections is σ(naphthalene): σ(2-methylnaphthalene) = 1.08 ± 0.05:1. The energy transfer probability density function shows that naphthalene has a little larger probability at small T → V/R energy transfer, ΔE_u< 300 cm^(-1), and 2-methylnaphthalene has a little large probability at large V → T energy transfer, -800 cm^(-1) < ΔE_d < -100 cm^(-1). However, these differences are close to our experimental uncertainty. No significant difference in the probability of very large energy transfer, such as supercollisions defined arbitrarily as ΔE_d < -1500 cm^(-1), was observed. No obvious methylation effect observed in this work may be due to the larger size of molecules we used than that (benzene and toluene) in the previous studies. That reduces the influence of the methylation effects in our experiments. The other possibility is that methylation effects may be due to the subsequent successive collisions or internal rotation at room temperature. The energy transfer may result in large difference due to the rotational effects.
Subjects
collision energy transfer
naphthalene
2-methylnaphthalene
methylation effects
crossed-molecular beam
velocity map ion imaging
Type
thesis
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