15min:

S. A. REID, C. TAO AND C. MUKARAKATE, Department of Chemistry, Marquette University, Milwaukee, WI 53233.

We report the first observation of the gas-phase electronic spectrum of a simple halocarbocation, CH₂I⁺. Fluorescence excitation and emission spectra were measured under jet-cooled conditions using a pulsed discharge source with CH₂I₂ as precursor. The spectral carrier was identified by: (1) comparison of experimentally derived ground state vibrational frequencies for various isotopomers with the predictions of Density Functional Theory (DFT) calculations, and (2) simulation of the observed rotational contour in our excitation spectra, which indicated an a-type transition, consistent with an excited state of A₁ symmetry. Calculations predict a triplet A₁ excited state with transition energy in the visible region, and the observed transition is therefore assigned as ³A₁-¹A₁, with band origin at ~ 15180 cm^-1.