Low-energy-ion bombardment of ices. [kev range]

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:6091691

Christiansen, J W

The interaction of low energy ions with ices has been investigated. In the first set of experiments the author has measured the sputtering yields of H{sub 2}O, CO{sub 2}, and N{sub 2}O ices at 78 K under Ar{sup +}, Ne{sup +}, and He{sup +} bombardment in the keV energy range. The experimental technique involves the determination of the ice film thickness by optical interference and the fluence required to sputter through the film. The measured yields were compared with predictions using Sigmunds linear cascade theory. The results indicate that other processes other than a purely ballistic process contribute to the ejection. In the second set of experiment the mass distribution of (H{sub 2}O){sub n}H{sup +} ion clusters desorbed from ice at 78 K by 6 keV Ne{sup +}, Ar{sup +}, and Kr{sup +} primary ions was measured for 1 {le} n {le} 40. The cluster formation was assumed to occur without charge-transfer. The mass distribution can be described by Rice-Ramsperger-Kassel (RPK) theory which fits the relative ion yields Y{sub n}/Y{sub 1}, i.e. the ratio of the yield of the nth cluster to that of the first as a function of n. The energy deposited per normal mode required for desorption caused by each bombarding ion species is calculated from our theoretical fits to the experimental data. This is then compared with the energy deposited per mode estimated from the energy loss by nuclear stopping of the bombarding ion in the ice. Reasonable agreement between the two is obtained. The existence of the magic number cluster ion (H{sub 2}O){sub 4}H{sup +} was observed in each of the three bombarding schemes. In the final set of experiments the mass distribution for Ar{sup +} ion clusters desorbed from solid Ar at 20 K by 6 keV Ne{sup +}, Ar{sup +}, and Kr{sup +} ion bombardment was measured.

• Research Organization: Arizona State Univ., Tempe, AZ (USA)
• OSTI ID: 6091691
• Country of Publication: United States
• Language: English

Related Subjects

656003* -- Condensed Matter Physics-- Interactions between Beams & Condensed Matter-- (1987-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ARGON IONS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CATIONS
CHALCOGENIDES
CHARGED PARTICLES
COLLISIONS
COMPARATIVE EVALUATIONS
DATA
DESORPTION
DISTRIBUTION
ENERGY LOSSES
ENERGY RANGE
EXPERIMENTAL DATA
HELIUM IONS
HYDROGEN COMPOUNDS
ICE
INFORMATION
ION PAIRS
IONS
KEV RANGE
KEV RANGE 01-10
LOSSES
MASS DISTRIBUTION
NEON IONS
NITROGEN COMPOUNDS
NITROGEN OXIDES
NITROUS OXIDE
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
SPATIAL DISTRIBUTION
SPUTTERING
WATER