CHRISTOPHER F. NEESE, CHRISTOPHER P. MORONG, JENNIFER L. GOTTFRIED AND TAKESHI OKA, Department of Chemistry, Department of Astronomy & Astrophysics, and the Enrico Fermi Institute, The University of Chicago, Chicago IL, 60637, USA.
The methylene ion, CH2+, is of special theoretical interest because it is both quasi-linear and exhibits a strong Renner-Teller interaction between its ground and first-excited electronic states. At linearity, the ground state is a 2 u state that splits into X2A1 and A2B1 states as the molecule bends. The A state is linear, while the X state is quasi-linear with a barrier to linearity of only 1089~cm-1.
Since 2002 we have been studying the spectrum of \textCH2+ with our Ti:sapphire laser spectrometer. This spectrometer couples velocity modulation with heterodyne detection for near shot-noise-limited sensitivity. Since last year's symposium we have assigned the A(0,9,0)2 X(0,0,0)3 and A(0,9,0)4 X(0,0,0)3 bands. These bands are the first high-resolution detection of Ka=3 levels for the ground state. In addition, the A(0,9,0)2 X(0,0,0)3 can be combined with the previously studied A(0,9,0)2 X(0,0,0)1 band to produce Ka= 3-1 combination differences for the ground state. The current analysis of the complete near-infrared spectrum will be discussed.