Abstract
Thirty-five far infra-red laser lines in CH3Br excited by a CO2 laser were observed by Chang and McGee. Assignments are proposed for these laser lines as well as for the CH3Br transitions which are pumped. The isotopic species involved is determined in each case. For the v 6 perpendicular band, these data yield a complete set of band parameters. We find for CH3 79Br:
and for CH3 81Br: