Accession Number:

AD0720871

Title:

A Potential High Energy Resolution Iodine Negative Ion Source,

Descriptive Note:

Corporate Author:

MCDONNELL DOUGLAS ASTRONAUTICS CO ST LOUIS MO EASTERN DIV

Report Date:

1970-11-01

Pagination or Media Count:

18.0

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 HI 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

Subject Categories:

  • Physical Chemistry

Distribution Statement:

APPROVED FOR PUBLIC RELEASE