Desorption of NA from SiO_2 films, induced by low energy electrons: relevance to atmospheres of Mercury and the Moon.

Details Desorption of NA from SiO_2 films, induced by low energy electrons: relevance to atmospheres of Mercury and the Moon. Desorption of NA from SiO_2 films, induced by low energy electrons: relevance to atmospheres of Mercury and the Moon.

Sep 1998

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1998baas...30.1110y&link_type=abstract

American Astronomical Society, DPS meeting #30, #50.P07; Bulletin of the American Astronomical Society, Vol. 30, p.1110

Astronomy and Astrophysics

Astronomy

Scientific paper

As part of a program to probe the mechanisms by which Na atoms are produced in tenuous planetary atmospheres (e.g., Mercury, The Moon, etc.) [1] we are studying electron stimulated desorption (ESD) of sodium ions and neutral atoms from model mineral surfaces, i.e., ultrathin amorphous stoichiometric SiO_2 films ( 10nm thick) grown on a metal substrate. We report new data for ESD of neutral Na, and compare with ESD of ionic Na(+) . The neutral Na flux, desorbing from the surface under electron bombardment, is detected by using a novel surface ionization detector. This detector also permits measurements of energy distributions of neutral atoms by means of a time-of-flight method. Sodium ions, desorbing under electron bombardment, are detected by a quadrupole mass spectrometer, and ion energy distributions are measured using a retarding field method.The appearance threshold for ionic Na(+) desorption is observed at an incident electron energy E_e 25eV, corresponding to O2s core level excitation. A Coulomb pair O(+) - Na(+) is believed to form as a result of intraatomic Auger decay in the surface oxygen atom, leading to Na(+) desorption. In contrast, the threshold for neutral Na desorption occurs for lower values of electron energy. The Na yield shows a sharp onset at E 1 to 2eV , passes through a maximum at 8eV and rises monotonically above 15eV (energies not corrected for work function). The desorption of neutral Na is interpreted in terms of a substrate-mediated charge transfer process. The desorbing Na atoms are "hot", with most probable kinetic energies of 0.1eV. The cross section for ESD of neutral Na by 200eV electrons is 5 x 10(-19) cm(2) . [1] T.E. Madey, B.V. Yakshinskiy, V.N. Ageev, R.E. Johnson. J. Geophys. Res. 103, 5873-5877 (1998).

Affiliated with

Also associated with

No associations

Rating

Desorption of NA from SiO_2 films, induced by low energy electrons: relevance to atmospheres of Mercury and the Moon. does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Desorption of NA from SiO_2 films, induced by low energy electrons: relevance to atmospheres of Mercury and the Moon., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Desorption of NA from SiO_2 films, induced by low energy electrons: relevance to atmospheres of Mercury and the Moon. will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-813745