Accession Number : AD0709229

Title :   A DIRECT MASS SPECTROMETRIC STUDY OF THE FORMATION AND REACTIONS OF WATER-CLUSTER IONS.

Descriptive Note : Final rept. 15 Mar 68-15 Mar 70,

Corporate Author : MIDWEST RESEARCH INST KANSAS CITY MO

Personal Author(s) : Milne,Thomas A. ; Beachey,Jacob E. ; Greene,Frank T.

Report Date : 09 JUN 1970

Pagination or Media Count : 36

Abstract : In an effort to establish the reasonableness of one postulate as to the origin of water-cluster ions in the D-region of the atmosphere, the authors have investigated the direct electron-impact ionization properties of small water clusters. Water clusters were generated in free-jet expansions of moist Argon, yielding an electron-impact mass-spectrum consisting of the ion series H(+).(H2O)n. Electron impact appearance potential measurements are described, yielding appearance potentials substantially higher than predicted from thermochemical cycles involving ion dissociation energies. Measurements were made of the cluster mass-spectrum as a function of extent of nucleation, of the variation of appearance potentials with extent of nucleation and of fragment-ion kinetic energies. Results of these measurements lead to the conclusion that not only do the larger water clusters fragment by loss of H2O as well as of OH, but that substantial excess internal and fragment kinetic energy is involved. The utility of ion peak-shape analysis in detecting fragmentation of Argon clusters is illustrated. (Author)

Descriptors :   (*UPPER ATMOSPHERE, *WATER), MASS SPECTROSCOPY, IONIZATION, PROTONS, ELECTRON IRRADIATION, ARGON

Subject Categories : Atmospheric Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE