MOLECULAR ROTATIONAL CONTOUR FITTING OF ULTRA-HIGH-RESOLUTION PROFILES OF DIFFUSE INTERSTELLAR BANDS

The first application of molecular rotational contour fitting to the a nalysis of high-resolution profiles of the lambda lambda 6614 and 5797 diffuse interstellar absorption bands is described. A range of select ed molecular, electronic and transition dipole symmetries is considere d. It is found that the profile of lambda 6614 is well reproduced by a Coriolis-induced perpendicular electronic transition of a planar obla te symmetric top molecule. Based on this result and other consideratio ns, large carbon ring molecules emerge as good candidates for the carr iers of the lambda 6614 and (possibly) lambda 5797 bands. Molecular co nstants, molecular rotational temperatures and linewidth parameters co nsistent with the observational data for lambda 6614 are reported and compared with those anticipated for candidate diffuse band carriers an d with astronomical data obtained from studies of molecules in the sam e lines of sight. Some discrepancies between observed and fitted profi les are noted.