The formation of vibrationally excited hydrogen molecules on carbon surfaces

A novel technique for the measurement of the excitation of molecular hydrogen formed on surfaces has been applied to the study of H-2 formation on carbon. The results show that on certain carbon surfaces H-2 may form in vibrational levels as high as v = 7, and that at a surface temperature 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 contribution to the population of vibrationally excited hydrogen in the interstellar medium comes from the formation of molecular hydrogen on carbonaceous interstellar grains.