15min:

JINJUN LIU, Laser Spectroscopy Facility, Department of Chemistry, The Ohio State University, 120 W. 18th Avenue, Columbus, Ohio 43210 (present address: Laboratory of Physical Chemistry, ETH Zurich, Building HCI, Wolfgang-Pauli-Str. 10, 8093 Zurich, Switzerland); MING-WEI CHEN, Laser Spectroscopy Facility, Department of Chemistry, The Ohio State University, 120 W. 18th Avenue, Columbus, Ohio 43210; JOHN T. YI, Laser Spectroscopy Facility, Department of Chemistry, The Ohio State University, 120 W. 18th Avenue, Columbus, Ohio 43210 (present address: Department of Chemistry, Winston-Salem State University, Wilveria B. Atkinson Science Bldg, Room 311, Winston-Salem NC 27110); TERRY A. MILLER, Laser Spectroscopy Facility, Department of Chemistry, The Ohio State University, 120 W. 18th Avenue, Columbus, Ohio 43210.

Methoxy radical, CH₃O is a widely studied and benchmark molecule, both for its spectroscopy and its role in chemical reactions. It possesses a ground ²E state which is distorted by the Jahn-Teller interaction and split into ²E_1/2 and ²E_3/2 components by the spin-orbit interaction. The LIF spectra of the A²A₁--X²E transitions is well-known, but under jet expansion conditions the E_1/2 component is not observed because it is 60cm^-1 higher than E_3/2 and not populated. A feasible way to study the features of the X²E_1/2 level is to use the Stimulated Emission Pumping (SEP) technique. We have combined our high-resolution laser-induced fluorescence (LIF) spectroscopic ( 200MHz) with a moderate-resolution laser ( 0.2cm^-1). These lasers are controlled by a computer program, which permits both the pump and dump lasers to be fired at specified delays after the photolysis laser producing CH₃O. SEP spectra of CH₃O were recorded with a resolution of ~300MHz linewidth and measured with a precision <100MHz and these data were included in a global data (LIF, SEP, microwave) fitting to determine the parameters of the X²E_1/2 state. The previous assignment of parity for the ²E_1/2 state is modified and the value of the spin-orbit splitting revised.