Measurement of the dissociation rate of molecular ions

Description

The time interval between the ionization of a molecule by electron impact and its dissociation was determined from the kinetic energy of the fragment ions. This technique allows a direct differential sampling of the dissociation rate at various times, in contrast to previous, integral methods. The use of disc-shaped molecular beam of 28 micrometers half-width and a draw-out field of 10,000 V/cm in the ionization region resulted in a minimum measured time interval of 7.4 nonoseconds. The longest times measured were between 5 and 6 microseconds. The time dependence of the decomposition rate was measured for two decompositions in butane, five in heptane, three in benzene, one in CD4 and one in CO2(++), with rather similar results. It was established that the decay is not exponential. All decay curves, plotted semi-logarithmically, were found to have an increasing slope towards shorter times, indicating contributions from a variety of rate constants in agreement with the predictions of the statistical theory of ion decompositions.

Subjects

Series Statement

• Translations -- no. 25

Other Editions

• Measurement of the dissociation rate of molecular ionsUnited States Air Force, Office of Aerospace Research, Air Force Cambridge Research Laboratories, AFCRL Research Library1968-01-01
• Measurement of the dissociation rate of molecular ionsUnited States Air Force, Office of Aerospace Research, Air Force Cambridge Research Laboratories, AFCRL Research Library1968