Infrared absorption spectroscopy of d-3: an investigation into the formation mechanisms of triatomic hydrogenic species - discussion

Infrared absorption spectra of D3 are observed with a difference frequency laser system in the frequency ranges around 3600cm-1 (3s2A'1 - 3p 2E') and 3900cm-1 (3d - 3p 2E'). The observed line shapes exhibit a non-M axwellian velocity distribution, and the translational energy is derived to be ca.0.4eV. From this finding, it is concluded that D3 is forme d through the dissociative recombination reaction D5+ wit h electrons. The rotational dependence of the line shapes of the 3600cm-1 band is brought about by a competition between the predissociation in the 3s 2A'1 state and the radiative decay in the 3p2E' state. The shorter lifetimes of the 3d complex make the lin e shape of the 3900cm-1 band simpler, a superposition of two absorpt ion profiles with different widths. The greater widths of the absorption lines of the 3900cm-1 band are attributed to unresolved spin-splittings.