Spectroscopy and reaction dynamics of open-shell species: A quantum state resolved perspective

PHYS 72

David J. Nesbitt, djn@jila.colorado.edu, JILA/Department of Chemistry and Biochemistry, JILA/NIST and University of Colorado, Box 440, University of Colorado, Boulder, CO 80309, Feng Dong, f.dong@lgrinc.com, Los Gatos Research, 67 E. Evelyn Ave. Suite 3, Mountain View, CA 94041, Melanie Roberts, Melanie.Roberts@colorado.edu, Department of Chemistry and Biochemistry, Department of Chemistry and Biochemistry, JILA Box 440, University of Colorado, Boulder, 80309, Alex Zolot, Department of Chemistry and Biochemistry, JILA/University of Colorado, Boulder, CO 80309, and Michael Ziemkiewicz, JILA, University of Colorado, University of Colorado, Boulder, CO 80309.
The combination of radical sources and high resolution infrared absorption provides a powerful window into both spectroscopy and dynamics of open shell species. Time permitting, this talk will address recent work from our group in two areas. 1) High-resolution IR spectra of jet-cooled vinyl radical (H2CCH) in the symmetric C-H stretch region have been observed for the first time, in excellent agreement with anharmonically scaled high level ab initio calculations, but red shifted considerably from previous low resolution assignments. Boltzmann analysis indicates unexpected nuclear spin statistics in the tunneling levels, which suggests the novel possibility of large amplitude “roaming” of all three H atoms for vinyl states initially formed in the discharge. 2) Reactive scattering of F + H2O → HF + OH has been investigated under single collision, crossed jet conditions via IR laser absorption detection of nascent HF(v, J) states. The vibrational populations are highly inverted with rotationally hyperthermal HF (v=0) populations up to J=15–17 (Erot ≈ 15 kcal/mol), which is consistent with ab initio predictions of early barrier dynamics and a strongly bent transition state.