TITLE

A high resolution spectroscopic study of the open-shell complex ArNO2

AUTHOR(S)
Low, Russell J.; Brookes, Matthew D.; Whitham, Christopher J.; Howard, Brian J.
PUB. DATE
October 1996
SOURCE
Journal of Chemical Physics;10/22/1996, Vol. 105 Issue 16, p6756
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Microwave and infrared spectra of the open-shell complex ArNO2 have been recorded. The microwave spectrum (6–18 GHz) consisted solely of the a-type transitions 505←404, 404←303, 303←202, and 202←101 involving the Ka=0 state and 523←422, 524←423, 422←321, 423←322, 321←220, 322←221 involving the Ka=2 state. These transitions showed structure due to fine, magnetic hyperfine and electric quadrupole interactions. The infrared spectrum, associated with the ν3 asymmetric vibrational mode of the NO2 monomer, consisted of three bands (RP0, RQ0, and RR0 and both K doublets of PP2, PQ2, and PR2) centered around 1615 cm-1. The data have been fitted to a semirigid Hamiltonian to determine the molecular parameters. The derived parameters are analyzed in terms of those of the free NO2 radical. Changes in these parameters upon complexation can be caused by a geometric effect due to the rotation of the inertial axes from the monomer to the complex, and an electronic effect caused by a distortion of the electronic wave functions on complex formation. The electronic changes (which may give an indication of incipient chemical bond formation) are shown to be very small. The absence of odd Ka″ states in both the infrared and microwave spectra was rationalized in terms of a high frequency tunneling motion of the NO2 within the complex. Both a dynamics calculation and a model potential based on atom–atom interactions provided additional support for a nonplanar equilibrium structure with a low barrier to planarity. © 1996 American Institute of Physics.
ACCESSION #
7640084

 

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