PGOPHER

PGOPHER is a general purpose program for simulating and fitting rotational spectra. PGOPHER will handle linear molecules and symmetric and asymmetric tops, including effects due to unpaired electrons and nuclear spin. The program can handle many sorts of transitions, including Raman, multiphoton and forbidden transitions. It can simulate multiple species and states simultaneously, including special effects such as perturbations and state dependent predissociation. Fitting can be to line positions or band contours.
Find PGOPHER at: http://pgopher.chm.bris.ac.uk/