Rotational and vibrational energy effects on ion-molecule reactivity as studied by the VT-SIFDT technique

被引:89
作者
Viggiano, AA
Morris, RA
机构
[1] Phillips Laboratory, Geophysics Directorate, Ionospheric Effects Division (GPID), Hanscom AFB, MA 01731-3010
关键词
D O I
10.1021/jp962084x
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
A method is described for measuring internal energy dependences of gas phase ion-molecule reactions in a variable temperature-selected ion flow drift tube (VT-SIFDT) instrument. Numerous studies have been conducted to examine the effects of both rotational and vibrational excitation on late constants and branching ratios. Rotational and translational energy are found to be equally efficient at driving endothermic reactions. For exothermic reactions, large rotational effects are found only when one or both of the reagents have a large rotational constant. This indicates that changing from a low to moderate J value can affect reactivity but that changing from moderate to high J has little influence on reactivity. Vibrational effects are more varied. In some reactions, vibrational excitation in the anticipated reaction coordinate strongly affects reactivity, while in other cases it does not. Vibrational effects are often observed in charge transfer reactions, presumably due to energy resonances and Franck-Condon arguments. For the S(N)2 reactions studied to date, vibrations play no role in governing reactivity for halide ions reacting with methyl halides, while vibrations are equivalent to other types of energy in influencing the reactivity of non-methyl halide systems.
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收藏
页码:19227 / 19240
页数:14
相关论文
共 109 条
[1]   SELECTED ION FLOW TUBE (SIFT) - TECHNIQUE FOR STUDYING ION-NEUTRAL REACTIONS [J].
ADAMS, NG ;
SMITH, D .
INTERNATIONAL JOURNAL OF MASS SPECTROMETRY AND ION PROCESSES, 1976, 21 (3-4) :349-359
[2]   COMPARATIVE EFFECTS OF TEMPERATURE AND KINETIC-ENERGY CHANGE ON THE REACTION OF O-2+ WITH CH4 AND CD4 [J].
ADAMS, NG ;
SMITH, D ;
FERGUSON, EE .
INTERNATIONAL JOURNAL OF MASS SPECTROMETRY AND ION PROCESSES, 1985, 67 (01) :67-74
[3]   EFFECTS OF ION SPEED DISTRIBUTIONS IN FLOW-DRIFT TUBE STUDIES OF ION-NEUTRAL REACTIONS [J].
ALBRITTON, DL ;
DOTAN, I ;
LINDINGER, W ;
MCFARLAND, M ;
TELLINGHUISEN, J ;
FEHSENFELD, FC .
JOURNAL OF CHEMICAL PHYSICS, 1977, 66 (02) :410-421
[4]  
ALBRITTON DL, 1979, KINETICS ION MOL REA
[5]  
ANDERSON SL, 1992, STATE SELECTED STA 1
[6]  
ARMAEE B, 1987, FARADAY DISCUSS CHEM, V84, P387
[7]  
Baer T., 1979, GAS PHASE ION CHEM
[8]   REACTIONS OF O-+N2O AT 300-K - THE TOTALLY LABELED EXPERIMENTS [J].
BARLOW, SE ;
BIERBAUM, VM .
JOURNAL OF CHEMICAL PHYSICS, 1990, 92 (06) :3442-3447
[9]  
CHASE MW, 1985, J PHYS CHEM REF DATA, V14, P1
[10]  
CHIU Y, IN PRESS J CHEM PHYS