re: Lunar Sourcebook data
From p. 40:
"The Lunar atmosphere is extremely tenuous. The undisturbed gas concentration is only about 2x10^5 molecules/cm^3 during the lunar night, falling to perhaps 10^4 molecules/cm^3 during the Lunar day (Hodges et al., 1975). This is about 14 orders of magnitude less than the Earth's atmosphere..."
It goes on to talk about the nature of the Lunar atmosphere (mostly neon, hydrogen, helium and argon). If you stop by the LPI website you should pick up a digital copy of the Lunar Sourcebook. It is the primo reference on Lunar science results.