The viability of a two-photon absorption mechanism

Recent studies have suggested that a two-photon Lyman alpha driven absorption mechanism in H2 or H + 2 is responsible for the diffuse interstellar absorption bands. This hypothesis differs radically from previous theories on the origin of the diffuse interstellar bands. In order to test the validity of the H+2 hypothesis, a study is undertaken to calculate the exact properties of the H+2 spectrum relevant to the proposed two-photon mechanism. Using the Born-Oppenheimer approximation, wavelengths and cross sections for the two-photon mechanism were calculated and compared to the diffuse interstellar absorption spectrum. The results of this study indicate that the H+2 spectrum does not match the observed diffuse interstellar band spectrum.