In:
The Journal of Chemical Physics, AIP Publishing, Vol. 82, No. 5 ( 1985-03-01), p. 2196-2205
Abstract:
The N–O degenerate stretching band ν3 of the NO3 radical has been studied in the gas phase by infrared tunable diode laser spectroscopy. The NO3 radical was generated by the reaction of NO2 with an excess of O3. Zeeman modulation was employed to observe the paramagnetic absorption lines of 14NO3 and 15NO3 in the wavelength regions 1480–1500 and 1463–1479 cm−1, respectively. Only K′′=3n (n denoting an integer) transitions were observed, and the N′′=even members were missing from the K′′=0 manifold. These observations indicate that the NO3 radical belongs to D3h symmetry in the 2A2′ ground electronic state. The observed spectrum was analyzed using a symmetric-top vibration-rotation Hamiltonian including the spin-rotation interaction. The main parameters thus obtained for 14NO3 are B3=0.455 22(11), C3=0.227 13(6), Cζ3=0.044 79(11), q3=0.001 624(33), t3= 0.000 000 458 0(43), B0=0.457 46(12), C0=B0/2 (fixed), εbb=0.0280(27), and εcc=0.1197(36) for v3=1, εbb=0.0277(28), and εcc=0.1117(34) for v=0, and ν0=1492.3929(9), all in cm−1 with one standard error in parentheses. Although these parameters well reproduced the observed spectrum, the following anomalous features were noted: (1) a large εcc spin-rotation interaction constant was required to explain the spin splittings for both the ν3 and ground states, (2) a higher-order vibration-rotation interaction term having Δk=±4 and Δl=±2 needed to be included, with the corresponding interaction constant t3 larger than that of CHF3, and (3) the centrifugal distortion constants and the first order Coriolis coupling constant which were derived did not agree with those calculated assuming a reasonable force field. These anomalies were ascribed to the interaction with a low-lying excited electronic state and, to some extent, with a combination or overtone state. The N–O bond length was calculated from the B0 rotational constant to be 1.240 Å, in good agreement with an ab initio calculated value.
Type of Medium:
Online Resource
ISSN:
0021-9606
,
1089-7690
Language:
English
Publisher:
AIP Publishing
Publication Date:
1985
detail.hit.zdb_id:
3113-6
detail.hit.zdb_id:
1473050-9
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