EXPERIMENTAL AND COMPUTATIONAL STUDY OF NEUTRAL XENON HALIDES (XEX) IN THE GAS-PHASE FOR X=F, CL, BR, AND I

We report a combined experimental and theoretical study of the xenon m onohalide radicals XeX. (X=F, Cl, Br, and I) together with their catio nic and anionic counterparts XeX+ and XeX-. In brief, the XeX+ cations are characterized by reasonably strong chemical bonds with significan t charge-transfer stabilization, except for X=F. In contrast, the neut ral XeX. radicals as well as the XeX- anions can mostly be described i n terms of van der Waals complexes and exhibit bond strengths of only a few tenths of an electron volt. For both XeX. and XeX- the fluorides (X=F) are the most strongly bound among the xenon halides due to sign ificant covalency in the neutral radical, and to the large charge dens ity on fluoride in the XeX- anion, respectively. Mass spectrometric ex periments reveal the different behavior of xenon fluoride as compared to the ether halides, and in kiloelectron-volt collisions sequential e lectron transfer according to XeX+-->XeX.-->XeX- can be achieved allow ing one to generate neutral XeX. radicals with lifetimes of at least a few microseconds for X = F and I. (C) 1998 American Institute of Phys ics. [S0021-9606(98)02220-X]