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Direct measurement of surface carbon concentrationsMeasurements of surface concentrations of carbon in lunar soils and soil breccias provide information on the origin of carbon in the regolith. The reaction C-12 (d, p sub zero) is used to measure 'surface' and 'volume' concentrations in lunar samples. This method has a depth resolution of 1 micron, which permits only a 'surface' and a 'volume' component to be measured. Three of four Apollo 16 double drive tube samples show a surface carbon concentration of about 8 by 10 to the 14th power/sq cm, whereas the fourth sample gave 4 by 10 to the 14th power/sq cm. It can be convincingly shown that the measured concentration does not originate from fluorocarbon or hydrocarbon contaminants. Surface adsorbed layers of CO or CO2 are removed by a sputter cleaning procedure using a 2-MeV F beam. It is shown that the residual C concentration of 8 by 10 to the 14th power/sq cm cannot be further reduced by increased F fluence, and it is therefore concluded that it is truly lunar. If one assumes that the measured surface C concentration is a steady-state concentration determined only by a balance between solar-wind implantation and sputtering, a sputter erosion rate of 0.1 A/yr is obtained. However, it would be more profitable to use an independently derived sputter erosion rate to test the hypothesis of a solar-wind origin of the surface carbon.
Document ID
19780057857
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Filleux, C.
(California Inst. of Tech. Pasadena, CA, United States)
Tombrello, T. A.
(California Inst. of Tech. Pasadena, CA, United States)
Burnett, D. S.
(California Institute of Technology Pasadena, Calif., United States)
Date Acquired
August 9, 2013
Publication Date
January 1, 1977
Subject Category
Lunar And Planetary Exploration
Meeting Information
Meeting: Lunar Science Conference
Location: Houston, TX
Start Date: March 14, 1977
End Date: March 18, 1977
Accession Number
78A41766
Funding Number(s)
CONTRACT_GRANT: NGR-05-002-333
CONTRACT_GRANT: NSF PHY-76-83685
Distribution Limits
Public
Copyright
Other

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