標題: 利用雷射光解-雷射誘發螢光法研究自由基C2H5S與O3的反應
Kinetics study of the reaction of C2H5S with O3 using Laser Photolysis/Laser-induced Fluorescence
作者: 王載德
Tsai-Te Wang
王念夏
Dr. Niann S. Wang
應用化學系碩博士班
關鍵字: 雷射誘發螢光; 乙硫基; 臭氧; 動力學;LIF; C2H5S; C2H5SOO; O3; O2;kinetics
公開日期: 1998
摘要: 本研究利用雷射光解-雷射誘發螢光法(Laser Photoltsis/Laser-Induced Fluorescence)測量乙硫基(C2H5S)與臭氧(O3)的反應速率常數值。 C2H5S+O3-> products (1) 實驗中先以波長193 nm的雷射光光解乙硫醚(C2H5SC2H5),產生乙硫基;於反應進行時間內再以另一雷射光激發乙硫基至電子激發態,再由其發出之螢光偵測乙硫基濃度的變化。實驗條件控制為[O3]>> [C2H5S]0,使反應在擬一級(pseudo-first-order)狀況下進行。在反應中並加入少量氧氣以避免由乙基再生的乙硫基干擾反應。 實驗溫度範圍為215 K至423 K,室溫下所得的kII值為(7.55±0.18)×10-12 cm3 molecule-1 s-1,在不同壓力(60-154 torr)下得到的結果可知本實驗並無明顯之壓力效應。kII在272 K到423 K之阿瑞尼士表示式為: k(T)=(4.02±0.32)×10-12 exp[(185±26)/T] cm3 molecule-1 s-1 其反應活化能為-1.54 kJ/mole。 在溫度低於254 K,加入過量氧氣時,我們觀察到了平衡的現象,推測是乙硫基與其氧化加成物(C2H5SOO)達成了平衡,並測得平衡常數值。 C2H5S+O2+M U C2H5SOO+M (2) 我們也利用FACSIMILE26來模擬而求得此加成物與O3的反應速率常數。
C2H5S radical is an important intermediate in the oxidation process of organic sulfur compound in troposphere. We have determined the rate coefficient for the reaction of C2H5S+O3 using laser photolysis/laser-induced fluorescence method. A few torrs of O2 were added to the system to prevent C2H5S regeneration. Negative temperature dependence were observed at 272-423 K. k(T)=(4.02±0.32)×10-12exp[(185±26)/T] cm3 molecule-1 s-1 At temperature lower than 272 K, we also observed the equilibrium between C2H5S and C2H5SOO with aboundance of O2. C2H5S+O2+M U C2H5SOO+M (2) We use FACSIMILE26 to simulate the system and obtain equilibrium constants and the reaction rates of the adducts with O3.
URI: http://140.113.39.130/cdrfb3/record/nctu/#NT870500043
http://hdl.handle.net/11536/64821
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