CH3I擬似線性分子而具解離速度極快(〜0.1 ps)，光解波長220~350 nm，其特性可以用二維的位能圖譜來描述，因此無論是在研究光化學的實驗或是理論上都是一個好的對象。經由特定波長CH3I吸收單光子到Ã-波段，解離產生CH3 X(2A2˝)和I(2P3/2)或I*(2P1/2)。本實驗利用紅外光發射的技術來探討CH3I 光解的動力學反應，偵測248 nm雷射光解CH3I產生的I*螢光(1.315 μm) ，並加入不同的氣體和I*反應，藉由螢光的衰減來研究其反應動力學。

Methyl iodide photolysis has drawn considerable attention over the past years as an “instantaneous” pseudo-linear dissociation that may be described by a two dimensional potential energy surface. Single photon excitation in methyl iodide results in a direct rupture of the C-I bound, and the dissociation occurs in 〜0.1 ps. The Ã-band photodissocation of methyl iodide yields ground state methyl radicals [CH3 X(2A2˝)] and either ground state iodine atoms [(2P3/2)I≡I] or spin-orbit excited iodine atoms [(2P1/2)I≡I*] .
In the present work, we used the IR emission technique to study the kinetics of CH3I photolysis. The intensity of 1.315 μm infrared fluorescence from I* (2P1/2) is detected and analyzed. We have studied the influences on I* emissions by a variety of quenchers. Their roles in additional reactions and the quenching mechanism were reported.

謝誌 i
論文提要 ii
Abstract iii
Content iv
List of Figures v

Introduction 1
Theory 4
Experimental 6
Instrument and Apparatus 6
Method 15
Result and Discussion 16
Ⅰ. Dependences of I* emission intensity on CH3I pressure 16
Ⅱ.Second peak of CH3I dissociation 22
Ⅲ. I* quenching by foreign gases 25
A. I* quenching by H2 25
B. I* quenching by O2 29
C. I* quenching by N2O 33
D. I* quenching by N2 37
E. I* quenching by Ar 40
F. I* quenching by methane 43
G. I* quenching by n-pentane 46
H. I* quenching by n-hexane 49
Conclusion 52
Reference 54
Appendix 56

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