How readily does carbon 14 volatilize from (meta)stable forms of elemental carbon? Both graphite and diamond burn in hot air but are very stable in contact with cold air. Carbon 14 has maximum decay energy of 159 keV. At that energy, the electrons are stopped by 20 cm of air, or about 0,2 mm of water/tissue. Skin stops 89% of carbon 14 radiation, and cloth/gloves all of it. The recoil energy of N-14 is by my estimate maximum of 6 eV, so it gets nowhere. But how efficient are 159 keV electrons in dislodging C atoms from surface of carbon, such that they do oxidize in air to CO2, which can then be inhaled and incorporated in body? Presumably, the activity of the surface of carbon is proportional to the square of concentration of C-14, right? The intensity of beta radiation and thus the amount of C atoms dislodged from surface into air is proportional to one power, and the probability that an atom if dislodged is C-14 one is proportional to the other power. How much does the ease of dislodging carbon from surface differ between graphite and diamond?