H/sup -/ and D/sup -/ production by backscattering from alkali-metal targets
Measurements have been made of the total backscattered D/sup -/ and H/sup -/ yields from thick, clean targets of Cs, Rb, K, Na, and Li, bombarded with H/sup +//sub 2/, H/sup +//sub 3/, D/sup +//sub 2/, D/sup +//sub 3/ with incident energies from 0.15 to 4.0 keV/nucleus. All of the measurements were made at background pressures less than 10/sup -9/ Torr, and the alkali-metal targets were evaporated onto a cold substrate (Tapprox.77 K) in situ to assure thick, uncontaminated targets. For each target, the H/sup -/ and D/sup -/ yields exhibited maxima (as high as 0.08 per incident proton or deuteron) at incident energies between 0.3 and 1.4 keV/nucleus. For both hydrogen and deuterium incident at any energy, the negative-ion yield decreases in going form Cs to Li in the order given above. Also, a definite isotope effect was observed for every target used, with the H/sup -/ yield peaking at a lower incident energy than the D/sup -/ yield and in most cases, the maximum H/sup -/ yield was higher than the maximum D/sup -/ yield. Measurements of the D/sup -/ yield as a function of Cs coverage were also made for D/sub 3//sup ts+/ bombarding a Ni substrate. The D/sup -/ yield maximized at or near the coverage at which the surface work function reached a minimum.
- Research Organization:
- Lawrence Berkeley Laboratory, University of California , Berkeley, California 94720
- OSTI ID:
- 6981504
- Journal Information:
- Phys. Rev. B: Condens. Matter; (United States), Vol. 23:3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
ALKALI METALS
MOLECULE COLLISIONS
DEUTERIUM
BACKSCATTERING
HYDROGEN
CESIUM
DEUTERIUM IONS
EV RANGE 100-1000
HYDROGEN IONS
ION BEAMS
KEV RANGE
LITHIUM
MOLECULAR BEAMS
POTASSIUM
RUBIDIUM
SODIUM
WORK FUNCTIONS
BEAMS
CHARGED PARTICLES
COLLISIONS
ELEMENTS
ENERGY RANGE
EV RANGE
FUNCTIONS
HYDROGEN ISOTOPES
IONS
ISOTOPES
LIGHT NUCLEI
METALS
NONMETALS
NUCLEI
ODD-ODD NUCLEI
SCATTERING
STABLE ISOTOPES
640301* - Atomic
Molecular & Chemical Physics- Beams & their Reactions