The v6= 1 and v6= 2 vibrational states of DCF3

Rovibrational spectroscopy of the Fermi-interacting ν4=1 and ν3=ν6=1 levels of DCF3

“…In this case, no higher-order terms of the diagonal z-Coriolis interaction (s or r constants) were required, as they did not improve the standard deviation of the fit and were only poorly determined. It should be noted that the quartic and sextic centrifugal distortion constants are remarkably consistent with those of the ground and m 6 = 1 vibrational states [1].…”

“…Although the D-reduction does not fail as dramatically as in the m 5 = 1 level, where the critical parameter is even smaller (q 5 22 = À1.88 Â 10 À5 cm À1 ), we have preferred to use the Q-reduction in the present case of m 4 = 1 (and also in the m 3 = m 6 = 1 level). It reduces 1 The term -2(Cf 0 -Cf 00 )K appears as a sum in the wavenumber expression for the l 0 = +1 l 00 = +1 transitions, and as a difference in the corresponding expression of the l 0 = À1 l 00 = À1 transitions. 2 A difference band results from difference rovibrational transitions.…”

“…In addition to this, the intensities of the r Q K branches are further enhanced by the Fermi resonance, for which the intensity borrowing from the m 4 band is stronger than for the p Q K branches. hot bands, occurring in the m 6 spectral region near 500 cm À1 , were described and analyzed in a previous study [1]. In the m 3 region near 700 cm À1 , the strongest hot bands correspond to the so-called biparallel m 3 þ m AE1 6 À m AE1 6 band whose transitions follow the Dl 6 = DK = 0 and DJ = 0, ±1 selection rules.…”

“…[1] that, when combining spectra from two different regions, their simultaneous analysis may reveal a slight inconsistency of their absolute wavenumber calibration. A small discrepancy of calibration between the two regions of FT spectra could indeed be observed when the data from the hot bands were temporarily given zero weights in the fits.…”

“…Ref. [1] provides a reassignment of the m 6 fundamental band, together with the first highresolution study of the m 6 = 2 (A 1 + E) overtone level. It also includes a very accurate determination of all ground state rotational constants, including the axial ones, up to the sixth order.…”