作　　者： ; ; ; ; ; ;

机构地区： 中国科学技术大学化学与材料科学学院化学物理系

出　　处： 《高等学校化学学报》 1996年第3期456-459,共4页

摘　　要： 用２６６ｎｍ激光光解ＣＨＢｒ_３分子产生ＣＨ（Ｃ）态自由基，通过测量ＣＨ（Ｃ~２Σ~＋→Ｘ~２Ⅱ）的总荧光信号强度来测定室温下Ｏ_２、Ｎ_２、ｎ－Ｃ_５Ｈ_（１２）、ｎ－Ｃ_６Ｈ_（１４）和ｎ－Ｃ_７Ｈ_（１６）对ＣＨ（Ｃ~２Σ~＋，ｖ＇＝０）的猝灭常数．结果表明，这些碰撞伴侣（Ｏ_２和Ｎ_２例外）对ＣＨ（Ｘ、Ａ、Ｂ和Ｃ）的反应或猝灭速率常数ｋ存在下列关系：ｋ（Ｘ）＞ｋ（Ｂ）＞ｋ（Ａ）≈ｋ（Ｃ），且烷烃分子对ＣＨ（Ｃ）态的猝灭速率常数与对ＣＨ（Ｘ，Ａ，Ｂ）态的反应和猝灭速率常数具有类似的规律，即随烷烃分子中的Ｃ－Ｈ键数的增加而增大．电子激发态ＣＨ的猝灭机制可能属于入口通道控制，化学反应在猝灭过程中起着重要作用． The rate constants for quenching of CH (C2Σ+,v'=0) by O2,N2,n-C5H12,n-C6H14 and n-C7H16 molecules were measured at room temperature.CH (C2Σ+) was produced by 266 nm laser photolysis of CHBr3 and the total fluorescence intensity of CH(C→X) at (314. 8±1) nm was then monitored using a fast digital storage oscilloscope coupled with a microcomputer.The rate constants (k) for the total removal of CH (C)are compared with those of CH (X,A,B) states,and show to be k (X)>k(B) and k(C)for alkane quenchers,and the tendency of quenching rate constants for CH(C) is similar to those for CH(X,A,B)showing the increase with increasing the number of C-H bonds in alkane molecules.The results indicate that the quenching of CH (A,B,C)is probably the entrance-channel controlled process and the chemical reaction might play an important role in collisional quenching of CH (A,B,C).

关 键 词： 自由基 激光光解 猝灭速率常数 三溴甲烷

领　　域： [理学] [理学]