Semiempirical model for heavy element depletion in the interstellar medium

One important process operating in interstellar space is grain sputtering which preferentially destroys grains with weak binding energies and returns the constituent elements to the gas. An empirical relationship has been derived which reproduces the observed depletion factors (A/A/sub sun/) in interstellar gas by relating them to some preshock distribution factor (C) and the binding energy of the elements (B) in appropriate compounds: log (A/A/sub sun/ = C(B-B0/B)/sup 1/2/