GEOMETRY OF C-C3H2.+ - FRANCK-CONDON FACTORS IN PHOTOIONIZATION ARE A SENSITIVE PROBE OF POLYATOMIC ION STRUCTURE

We report a determination of the equilibrium bond lengths and angles for c-C3H2.+ by comparison of Franck-Condon factor simulations to an experimentally determined photoelectron spectrum of c-C3H2. Using the equilibrium geometry of the C-C3H2 from recent high-resolution microwave spectroscopic studies as the reference structure, and ab initio frequencies and force constants, we find the geometry of c-C3H2.+ to be r(C-H) = 1.084 angstrom, r(C-C) = 1.340 angstrom, r(C=C) = 1.394 angstrom, and angle HC2C3 = 151.4-degrees, with an estimated uncertainty of +/-2%.