Use of Rydberg atoms to probe negative ion lifetimes

Abstract

The lifetimes of the transient negative ions formed during dissociative electron capture by CHCl3 and CCl4 have been investigated through studies of electron transfer in collisions with K(nd) Rydberg atoms. Measurements of the velocity and angular distributions of the product positive and negative ions reveal that transient CHCl3- * ions formed by Rydberg electron attachment to CHCl3 undergo very rapid dissociation. Similar data indicate that CCl4- * ions formed through Rydberg electron capture by CCl4 have much longer lifetimes, on the order of 10 to 30 psec, consistent with the predictions of Rice-Ramsberger-Kassel-Marcus theory. © 1990 American Institute of Physics.