THE FORMATION OF VIBRATIONALLY EXCITED HYDROGEN MOLECULES ON CARBON SURFACES

A novel technique for the measurement of the excitation of molecular h ydrogen formed on surfaces has been applied to the study of H-2 format ion on carbon. The results show that on certain carbon surfaces H-2 ma y form in vibrational levels as high as v = 7, and that at a surface t emperature of 90 K between 2.6 and 7% of the molecules can be found in the v = 1 level. This supports the proposal that a significant contri bution to the population of vibrationally excited hydrogen in the inte rstellar medium comes from the formation of molecular hydrogen on carb onaceous interstellar grains.