| Summary: | 碩士 === 國立中央大學 === 物理研究所 === 92 === Sputtering of neutral and ionic atoms and molecules from surfaces
of astronomical materials is an important process from mass transfer,
mass evolution, and chemical evolution points of view. In a number of
astronomical environments, e.g., comets, asteroids, planetary satellites
and rings, and interplanetary dust grains, the yield, including ion and
neutral desorption, will allow us to determine the erosion rate due to
electronic excitation processes, which may be very important in cases
where solar VUV-EUV photons can reach the surfaces of icy bodies.
This experiment collected sputtered ions from ices which were
illuminated by VUV from a microwave-stimulated hydrogen flow
discharge lamp with main emission at Lyman-α at 121.6 nm. The
measured ion current will be one of the vital factors in understanding
mass evolution of ices on the interstellar matters.
The total ion yields of H2O、H2O+CO2、H2O+NH3 three different
ices prepared at 77 K were found to be 0.00065 ions/photon in H2O ice,
0.00058 ions/photon in H2O+CO2 ice, 0.00044 ions/photon in H2O+ NH3
ice. The results agrees quite well with the experimental data measured by
C. Y. Robert Wu although the later work was reported using a 58.4 nm
lamp instead of 121.6 nm in this case.
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