Abstract
The microwave double-photon transitions and have been observed for the symmetric-top molecules CCN and P using high-power microwave double resonance. The pumping of the transition of CCN was so efficient in the low-pressure region that a negative temperature was established between the and the levels, and induced emission was observed. The pressure variation of the efficiency of the double-photon pumping agreed quantitiatively with theoretical values calculated using the Göppert-Mayer formula for the relevant dipole matrix element and Karplus and Schwinger's formula for saturation. The experiment provides interesting information on collision-induced transitions in CCN.
- Received 27 March 1970
DOI:https://doi.org/10.1103/PhysRevA.2.587
©1970 American Physical Society