ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
The rotational spectrum of the O3–CH4 complex has been measured in a molecular beam using a pulsed-nozzle Fourier-transform microwave spectrometer. An a-type pure-rotation and a c-type rotation-inversion electric-dipole spectrum is observed, complicated by the nearly free internal rotation of the CH4 top and the inversion tunneling of the O3. The nuclear-spin statistics of the equivalent oxygen nuclei leads to only one tunneling component existing for each rotation–internal-rotation state, indicating that the transition state has a heavy-atom, C2v-symmetry geometry. The tunneling splitting is determined to be 30 to 40 MHz, dependent on the CH4 internal-rotor state. Only two of the three methane internal-rotor states have been assigned. These two states of A and F symmetry have asymmetric-rotor energy-level structures, weakly perturbed by the ozone-inversion tunneling. The zero-point structure of the complex has a heavy-atom plane of symmetry with the two terminal O atoms equidistant above and below this plane. The angle between the line joining the center of masses of the two subunits and the O3, C2 axis is 118.2(5)°, with the central O directed away from the CH4. The shortest O–C separation is 3.57 Å. The geometry of the complex suggests two outcomes for the reaction of an O atom produced by 267 nm photolysis of O3 in the complex (assuming that the initial O3 photodissociation dynamics are not perturbed by complexation), either nonreaction or reaction by stripping of a hydrogen atom at high impact parameters, leading to fast, highly rotationally excited, OH product. © 2000 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.482026
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