The infrared spectrum of CD3CN around 1380 cm(-1) has been studied at a res
olution of 0.0040 cm(-1). in this region the combination of two perpendicul
ar fundamentals nu(6) and nu(8) is located. In the spectrum only the parall
el component was observed although the path length was 150 m and the pressu
re 70 Pa. In this PAPE type band 1340 lines were assigned in 17 sub-bands.
The vibrational e-doubling and -resonance together with strong effects of r
otational l-resonances with the perpendicular component of the same vibrati
onal level were observed. In addition, the Coriolis resonance with nu(3) nu(8) and certain anharmonic perturbations complicated the analysis. To cre
ate a better model both the hot bands (nu(6) + nu(8))(0) - nu(8) and (nu(6)
+ nu(8))(2) - nu(8) were assigned (1508 lines) and analyzed together with
the PAPE band. In the hot band (nu(6) + nu(8))(0) - nu(8) the Q branch (P)Q
(1) around 1049.5 cm(-1) was found to have a doublet structure and the spli
tting in the sub-band gave direct information about the vibrational e-doubl
ing. The splitting of K Delta K = 1 sub-band in (nu(6) + nu(8))(2) - nu(8)
giving rise to two families of lines was detected, too. In the calculations
attention was paid to the main features of the PAPE problem, Higher order
fitting parameters were avoided to keep the results reliable. The standard
deviation 2.7 x 10(-3) cm(-1) may be considered satisfactory, when taking i
nto account the complexity of the whole system. (C) 2000 Elsevier Science B
.V. All rights reserved.