Infrared spectra and tunneling dynamics of the N2–D2O and OC–D2O complexes in the v2 bend region of D2O

Abstract

The rovibrational spectra of the N2-D2O and OC-D2O complexes in the v2 bend region of D2O have been measured in a supersonic slit jet expansion using a rapid-scan tunable diode laser spectrometer. Both a-type and b-type transitions were observed for these two complexes. All transitions are doubled, due to the heavy water tunneling within the complexes. Assuming the tunneling splittings are the same in K(a) = 0 and K(a) = 1, the band origins, all three rotational and several distortion constants of each tunneling state were determined for N2-D2O in the ground and excited vibrational states, and for OC-D2O in the excited vibrational state, respectively. The averaged band origin of OC-D2O is blueshifted by 2.241 cm(-1) from that of the v2 band of the D2O monomer, compared with 1.247 cm(-1) for N2-D2O. The tunneling splitting of N2-D2O in the ground state is 0.16359(28) cm(-1), which is about five times that of OC-D2O. The tunneling splittings decrease by about 26% for N2-D2O and 23% for OC-D2O, respectively, upon excitation of the D2O bending vibration, indicating an increase of the tunneling barrier in the excited vibrational state. The tunneling splittings are found to have a strong dependence on intramolecular vibrational excitation as well as a weak dependence on quantum number K(a).

6.2 μm spectrum and 6-dimensional morphed potentials of OC-H2O

“…These values compare with the values of 0.557 cm -1 for OC-H 2 O and 0.034 cm -1 for OC-D 2 O calculated by Bumgarner et al[4] assuming that the tunneling splitting is the same in the K = 0 and K = 1 states. The discrepancy in these values can be attribute to the fact that the tunneling splitting has a dependence on the quantum number K[62]. Oudejans and Miller[6] calculated the tunneling splitting in the K = 1 ground vibrational state of OC-H 2 O to be 0.304 cm -1 in agreement with our prediction of 0.The left panels of Fig.…”

The water–carbon monoxide dimer: new infrared spectra, ab initio rovibrational energy level calculations, and an interesting in-termolecular mode

“…There has been considerable progress in observing mid-infrared rotation-vibration spectra. Thus Brookes and McKellar 1 studied the C-O stretch region (4.7 µm), Oudjeans and Miller 4 the O-H stretch region (2.7 µm), Zhu et al 5 the D2O bending region (8.5 µm), and Rivera-Rivera et al 6 the H2O bending region (6.3 µm).…”

“…The two tunneling components correspond to the two possible relative spin orientations of the H or D nuclei, aligned or anti-aligned, and in previous spectroscopic studies they have been labeled as the A and B components. [1][2][3][4][5][6] The ground state, A, has relative statistical weights 1 (H2O-CO) or 2 (D2O-CO) while the B state has weights 3 or 1. These tunneling states correspond to the nuclear spin modifications of the isolated water molecule: A correlates with para-H2O and ortho-D2O, and B with ortho-H2O and para-D2O.…”

“…McKellar 1 studied the C-O stretch region (4.7 µm), Oudjeans and Miller 4 the O-H stretch region (2.7 µm), Zhu et al 5 the D2O bending region (8.5 µm), and Rivera-Rivera et al 6 the H2O bending region (6.3 µm).…”

Rovibrational analysis of the water bending vibration in the mid-infrared spectrum of atmospherically significant N2–H2O complex

“…The current rovibrational analysis is valuable for generation of accurate rovibrational spectroscopic data for the potential energy surface of N 2 -H 2 O and assessing of quantum chemical calculations used to evaluate intensities of vibrations as a function of temperature on the quantitation of N 2 -H 2 O continuum [4]. These results are also now available for comparison with the corresponding 2 bending vibration in the recorded spectrum [28] of N 2 -D 2 O.…”