Accession Number : AD0720871

Title :   A Potential High Energy Resolution Iodine Negative Ion Source,

Corporate Author : MCDONNELL DOUGLAS ASTRONAUTICS CO ST LOUIS MO EASTERN DIV

Personal Author(s) : Cowperthwaite,Ronald L. ; Myers,Howard

Report Date : 01 NOV 1970

Pagination or Media Count : 18

Abstract : The dissociative attachment reaction e + HI to H + I(-) is suggested as a source of I(-) ions. The desirable characteristics of the source are: (1) large attachment cross section, (2) small value of the H/I mass ratio, (3) nearly thermoneutral attachment, and (4) insensitive to the electron beam energy spread. When formed from stationary HI, these factors combine to give an I(-) energy spread of 2-3 millivolts. The dominant I(-) spread results from the thermal motion of HI, and is estimated to be 0.03 - 0.06 eV, FWHM. By using the heavy I(-) ion to bombard a stationary light target molecule, a large difference in laboratory and center-of-mass (CM) energy scales further improves energy resolution and calibration. The reaction I(-) + H2 to H2(-) + I is suggested for measuring the electron affinity of H2. For this case, the energy scale compression factor is 64.5 and the energy spread in the CM system, due to the I(-) spread, is estimated to be the order of one millivolt. (Author)

Descriptors :   (*IODINE, *ION BEAMS), ELECTRON IRRADIATION, IODIDES, IONIZATION, ION SOURCES

Subject Categories : Physical Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE