15min:

DAVID J. ROBICHAUD, KANA TAKEMATSU AND MITCHIO OKUMURA, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena CA 91125; PIN CHEN AND HERBERT PICKETT, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109; JOHN F. STANTON, Department of Chemistry, University of Texas, Austin, TX, 78712.

The Jahn-Teller effect in the first two excited states of NO₃ is poorly understood. There is increasing evidence for relatively strong Jahn-Teller and Pseudo-Jahn-Teller couplings in the A²E'' and B² E' states, suggesting that these states cannot be described by conventional Jahn-Teller hamiltonians. Our previous moderate resolution spectra of the forbidden A²E'' X² A₂' transition revealed further evidence of strong Jahn-Teller interactions, but could not establish if the upper state exhibited static Jahn-Teller distortion. The origin band is strictly forbidden by Herzberg-Teller selection rules, and the 0⁰ level can only be accessed via the weak 4₁⁰ hot band. Contour analysis of the partially resolved rotational structure could not definitively establish whether the zero-point averaged geometry has D_3h or C_2v symmetry. We report the first rotationally resolved spectrum of the 4₁⁰ vibronic band of NO₃ recorded by diode laser spectroscopy, using off-axis Integrated Cavity Output Spectroscopy (ICOS).