Luminescence and reflectance of tranquillity samples: Effects of irradiation and vitrification

Douglas B. Nash, James E. Conel, Raymond T. Greer

Luminescence measurements of Tranquillity samples indicate that energy efficiencies for excitation by protons and ultraviolet are in the range 10-6 or below and natural and induced thermoluminescence is even weaker. If these samples are typical, lunar surface luminescence cannot occur at reported levels. Comparison of proton luminescence spectra from the exterior and interior of rocks and fine fragments provides evidence of solar wind impingement on the moon's surface. Spectral reflectance and albedo measurements of fresh rock powders before and after both laboratory proton irradiation and fusion indicate that vitrification may be an important mechanism of lunar darkening.

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Materials
Curve 1
Temperature K: ~298 Wavelength Range, µm: 0.590-2.50 Geometry θ θ' ω: ~0°~0° Composition (weight percent), Specifications, and Remarks: Sample 10020 from Apollo 11 mission; fine-grained crystalline material powdered to <50µm; data extracted from smooth curve; MgO reference standard.
Curve 2
Temperature K: ~298 Wavelength Range, µm: 0.590-2.50 Geometry θ θ' ω: ~0°~0° Composition (weight percent), Specifications, and Remarks: Above specimen and conditions except measured after irradiation with 4 x 10¹⁹ cm⁻² 2 kev protons to simulate 2 x 10⁵ yrs of solar wind.
Curve 3
Temperature K: ~298 Wavelength Range, µm: 0.600-2.50 Geometry θ θ' ω: ~0°~0° Composition (weight percent), Specifications, and Remarks: Soil sample from Apollo 11 mission; fines <1.0 mm; data extracted from smooth curve; MgO reference standard.
Curve 4
Temperature K: ~298 Wavelength Range, µm: 0.325-0.703 Geometry θ θ' ω: ~0°~0° Composition (weight percent), Specifications, and Remarks: Similar to curve 7 specimen and conditions.
Curve 5
Temperature K: ~298 Wavelength Range, µm: 0.329-0.699 Geometry θ θ' ω: ~0°~0° Composition (weight percent), Specifications, and Remarks: Above specimen and conditions except measured after irradiation with 4 x 10¹⁹ cm⁻² 2 kev protons to simulate 2 x 10⁵ yrs of solar wind.
Curve 6
Temperature K: ~298 Wavelength Range, µm: 0.325-0.696 Geometry θ θ' ω: ~0°~0° Composition (weight percent), Specifications, and Remarks: Similar to curve 9 specimen and conditions.
Curve 7
Temperature K: ~298 Wavelength Range, µm: 0.236-0.359 Geometry θ θ' ω: ~0°~0° Composition (weight percent), Specifications, and Remarks: Similar to curve 7 specimen and conditions.
Curve 8
Temperature K: ~298 Wavelength Range, µm: 0.236-0.359 Geometry θ θ' ω: ~0°~0° Composition (weight percent), Specifications, and Remarks: Above specimen and conditions except measured after irradiation with 4 x 10¹⁹ cm⁻² 2 kev protons to simulate 2 x 10⁵ yrs of solar wind.
Curve 9
Temperature K: ~298 Wavelength Range, µm: 0.237-0.361 Geometry θ θ' ω: ~0°~0° Composition (weight percent), Specifications, and Remarks: Similar to curve 9 specimen and conditions.
Curve 10
Temperature K: ~298 Wavelength Range, µm: 0.580-2.50 Geometry θ θ' ω: ~0°~0° Composition (weight percent), Specifications, and Remarks: Sample 10020 from Apollo 11 mission; fine-grained crystalline material; fused; powdered to <50µm; data extracted from smooth curve; MgO reference standard.
Curve 11
Temperature K: ~298 Wavelength Range, µm: 0.590-2.49 Geometry θ θ' ω: ~0°~0° Composition (weight percent), Specifications, and Remarks: Above specimen and conditions except measured after irradiation with 2 x 10¹⁸ cm⁻² 2 kev protons to simulate 10⁴ yrs of solar wind.
Curve 12
Temperature K: ~298 Wavelength Range, µm: 0.330-0.699 Geometry θ θ' ω: ~0°~0° Composition (weight percent), Specifications, and Remarks: Similar to curve 16 specimen and conditions.
Curve 13
Temperature K: ~298 Wavelength Range, µm: 0.330-0.699 Geometry θ θ' ω: ~0°~0° Composition (weight percent), Specifications, and Remarks: Above specimen and conditions except measured after irradiation with 2 x 10¹⁹ cm⁻² 2 kev protons to simulate 10⁵ yrs of solar wind.
Curve 14
Temperature K: ~298 Wavelength Range, µm: 0.238-0.360 Geometry θ θ' ω: ~0°~0° Composition (weight percent), Specifications, and Remarks: Similar to curve 16 specimen and conditions.
Curve 15
Temperature K: ~298 Wavelength Range, µm: 0.233-0.360 Geometry θ θ' ω: ~0°~0° Composition (weight percent), Specifications, and Remarks: Above specimen and conditions except measured after irradiation with 2 x 10¹⁹ cm⁻² 2 kev protons to simulate 10⁵ yrs of solar wind.