New Far Infrared Laser Emissions from D2CO and H2CO Optically-Pumped by a TECO2 Laser

H₂CO and D₂CO were optically-pumped by a TE CO₂ laser and found to generate 7 and 64 new far infrared (FIR) lines, respectively. Most of the previously-reported D₂CO cw FIR lines were also produced well. With an intracavity low-pressure cw CO₂ gain cell, these previously reported cw FIR lines were found to oscillate efficiently. A well-developed cascade laser action and the oscillation of the cw FIR lines are the characteristic properties of a formaldehyde FIR laser pumped by a TE CO₂ laser. The origin of these properties is discussed, and it is suggested that a large electric dipole moment along the symmetry axis and small pump offsets probably play an important role.