15min:

MING-WEI CHEN, Laser Spectroscopy Facility, Department of Chemistry, The Ohio State University, 120 W. 18th Avenue, Columbus, Ohio 43210; KANA TAKEMATSU, MITCHIO OKUMURA, Arthor Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125; AND TERRY A. MILLER, Laser Spectroscopy Facility, Department of Chemistry, The Ohio State University, 120 W. 18th Avenue, Columbus, Ohio 43210.

Well-known as an important intermediate in atmospheric chemistry, the nitrate radical (NO₃) has been extensively studied both experimentally and theoretically. The three energetically lowest electronic states (X ²A₂', A ²E'', and B ²E') are strongly coupled by vibronic interactions and hence it is a textbook molecule for understanding the coupling between nearby potential energy surfaces. Such coupling has been treated in considerable detail theoretically.\footnoteJ. F. Stanton, J. Chem. Phys. , \underline\textbf126, 134309 (2007) However, corresponding experimental characterization of the interaction is much less detailed. The experimental results primarily consist of IR measurements of vibrational transitions in the ground state.\footnoteK. Kawaguchi, E. Hirota, T. Ishiwata, and I. Tanaka, J. Chem. Phys. , \underline\textbf93, 951 (1990)\footnoteK. Kawaguchi, T. Ishiwata, E. Hirota, and I. Tanaka, Chem. Phys. , \underline\textbf231, 193 (1998) In addition, the electronically forbidden A-X transition has been observed in ambient temperature CRDS studies.\footnoteA. Deev, J. Sommar, and M. Okumura, J. Chem. Phys. , \underline\textbf122, 224305 (2005) To understand both the Jahn-Teller and pseudo Jahn-Teller coupling in the molecule, further measurements are required with different selection rules and/or higher resolution to resolve the rotational structures of different transitions. In our group, a high-resolution (source ~ 100 MHz in NIR region), jet-cooled CRDS system\footnoteS. Wu, P. Dupr\acutee, and T. A. Miller, Phys. Chem. Chem. Phys. , \underline\textbf8, 1682, (2006) can be applied to rotationally resolve the electronically forbidden A-X transition. Furthermore, our high-resolution LIF/SEP system (source ~ 100 MHz) can provide the direct, rotationally resolved measurements of the B-X and B-A transitions by operating in the LIF and SEP modes respectively. Such data can provide unambiguous spectral assignments in the X, A and B states.