The specific reaction rates for reactions between ions and molecules when both the reacting partners have thermal energy only have been determined for several systems. These rates have been determined by using a combination of a pulsed ionizing beam followed by a variable time‐delay ion‐extraction pulse. The results are compared with the field strength dependent values obtained in the same source operated in the conventional manner. The apparent thermal rate constant for the reaction CH4++CH4→CH5++CH3 is 9.6×10−10 cm3 molecule−1 sec−1, but after correction is made for detector discrimination, the value becomes 17.0×10−10 cm3 molecule−1 sec−1. For the field strength dependent values the magnitude of the ionizing current has a strong effect upon the observed specific reaction rate. Operation under conditions where the ionizing current is 0.1 μA led to reproducible values for the specific reaction rates.
[1]
H. Weyssenhoff,et al.
ION–MOLECULE REACTIONS STUDIED BY TIME-OF-FLIGHT MASS SPECTROMETRY
,
1964
.
[2]
T. F. Moran,et al.
Cross Sections of Ion—Permanent‐Dipole Reactions by Mass Spectrometry
,
1963
.
[3]
W. Maier,et al.
Energy Dependence of Cross Sections for Ion—Molecule Reactions. Transfer of Hydrogen Atoms and Hydrogen Ions
,
1963
.
[4]
L. Friedman,et al.
Hydrogen—Helium Ion—Molecule Reactions
,
1963
.
[5]
D. Stevenson,et al.
Reactions of Gaseous Molecule Ions with Gaseous Molecules. IV. Experimental Method and Results
,
1958
.
[6]
George Gioumousis,et al.
Reactions of Gaseous Molecule Ions with Gaseous Molecules. V. Theory
,
1958
.
[7]
F. W. Lampe,et al.
Reactions of Gaseous Ions. I. Methane and Ethylene
,
1957
.