Topic I：Rotational and vibrational energy transfer effect of CH B2Σ-(v’=1) Topic II：Vibrational distribution of Br2 molecule following photo-dissociation of bromine containing molecules by using cavity ring down absorption spectroscopy.
Date Issued
2004
Date
2004
Author(s)
Huang, Hong-Yi
DOI
en-US
Abstract
Part I
In this thesis, it will be separated into two individual parts: part I and part II. Each part has two chapters.
In the chapter 1 of part I, some basic background of spectroscopy and Fourier transform infrared method is illustrated. And in the chapter 2 of part I, the fine state-resolved rotational and vibrational energy transfer of CH B2Σ- (v’=1, N) by collisions with Ar, CO, and N2O is illustrated. It is the first time to observe the rotational energy transfer and vibrational energy transfer processes of a specific fine state for B 2Σ- (v’=1) of CH radical. We use pump-probe technique to determine RET and VET rate constants of CH B (v’ = 1, 0≦ N ≦ 6) with collisions of Ar, CO, and N2O. The RET is anticipated to be larger than VET for each collider. The determined RET rate constants range from 10-11 to 10-10 cm3 molecule-1 s-1, while the determined VET rate constants range from 10-12 to 10-11 cm3 molecule-1 s-1. The relative values of RET and VET rate constants are consistent with the results founded by Cooper and Whitehead. The findings of multi-quantum changing within single collision suggest that the collisions possibly dominated by the long-range attractive force. The k’VET shows no rotational quantum number dependence for these three quenching gases. This conclusion is the same as the results reported previously by Crosley et al. and Whitehead et al.
The kVET of N2O is three times larger than that of CO and nine times larger than that of Ar, respectively. This result is related to polyatomic effect, permanent dipole moment, and inefficient vibration-translation transfer. The number of internal degrees of freedom of N2O is larger than that of CO and Ar, therefore N2O can remove more energy than CO and Ar within single collision. In other words, N2O is more efficient than CO and Ar. Polyatomic effect and permanent dipole moment play a role in vibration and rotational energy transfer process.
Part II
In the chapter 1 of part II, the basic working principle of cavity ring-down absorption spectroscopy (CRDAS) is introduced. In the first section in the chapter 2 of part II, the total continuous absorption which includes A – X, B – X, and C – X transition of pure diatomic bromine is obtained by using CRDAS. In the second section, the primary photodissociation channels of CHBr3 and CH2Br2 which is ignored in the past studies have been investigated.
CHBr3 + hν -->
Subjects
腔體振盪吸收法
轉動及振動能量轉移
雷射光譜
CH自由基
rotational and vibrational energy transfer
cavtiy ring down absorption spectroscopy
laser spectroscopy
CH radical
Type
thesis
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