The weakly bound complex NH₃-CO: Observation and analysis of spectra in the infrared (C-O stretching) and millimetre wave (76–106 GHz) regions

Rotational study of the NH3–CO complex: Millimeter-wave measurements and ab initio calculations

“…They continue the transition series observed previously at lower frequencies 4 lower-J lines. Then carefully searching we were able to detect the new K = 0-1 subband and measured five R(7)-R(11) transitions.…”

“…Using the reported data 4 for ortho-NH 3 -CO, we predicted and found 14 new transitions with higher J values than accessed in the previous study. These include five R(7)-R(11) transitions of the K = 1-0 subband, four R(16)-R(19) transitions of the K = 0-0 subband, and five R(16)-R(18) transitions of the K = 1-1 subband.…”

“…The previous IR and MMW studies 4 have shown that the spectrum and energy level pattern of ortho-NH 3 -CO are relatively simple, closely resembling those of the rare gas-CO complexes. The situation for para-NH 3 -CO was more complicated, and the observed states had K values differing by ±1 from those of the analogous ortho-NH 3 -CO states.…”

“…This subband was not observed in the previous MMW study, although the rotational constants for the K = 0 state were estimated from the IR spectrum. 4 The new K = 0-1 lines exhibit a doubling with quite large 65-75 MHz splitting. At the beginning, we even overlooked these doublings and detected only one K = 0(e)-1(e) subband.…”

“…Subsequently, a more extensive study of NH 3 -CO has been done by McKellar and co-workers, 4 where rovibrational (C-O stretching ≈2143 cm −1 ) and pure rotational (76-106 GHz) transitions were measured in a pulsed jet supersonic expansion. The spectra included several subbands of infrared (IR) v CO = 1-0 transitions, K = 1-0, K = 0-1, and K = 2-1, and a number of subbands of pure rotational millimeter-wave (MMW) transitions, K = 0-0, K = 1-1, K = 1-0, K = 2-1, in the v CO = 0 ground state.…”