Mode selective tunneling dynamics observed by high resolution spectroscopy of the bending fundamentals of N14H2D and N14D2H

High resolution (0.004 and 0.01cm−1 instrumental bandwidth) interferometric Fourier transform infrared spectra of N14H2D and N14D2H were measured on a Bomem DA002 spectrometer in a supersonic jet expansion and at room temperature. We report the analysis of the bending fundamentals of N14H2D with term values Tv(s)=1389.9063(2)cm−1 and Tv(a)=1390.4953(2)cm−1 for the ν4b fundamental and Tv(s)=1605.6404(7)cm−1 and Tv(a)=1591.0019(7)cm−1 for the ν4a fundamental, and of N14D2H with term values of Tv(s)=1233.3740(2)cm−1 and Tv(a)=1235.8904(2)cm−1 for the ν4a fundamental and Tv(s)=1461.7941(9)cm−1 and Tv(a)=1461.9918(19)cm−1 for the ν4b fundamental. In all cases Tv(s) gives the position of the symmetric inversion sublevel (with positive parity) and Tv(a) the position of the antisymmetric inversion sublevel (with negative parity). The notation for the fundamentals ν4a and ν4b is chosen by correlation with the degenerate ν4 mode in the C3v symmetric molecules NH3 and ND3. The degeneracy is lifted in Cs symmetry and...