Hannover 2003 – wissenschaftliches Programm
MO 6.12: Poster
Dienstag, 25. März 2003, 16:00–18:30, Lichthof
The chemiluminescent reaction Sr+ICl→SrCl*+I: fluorescence spectra and steric effects — •Axel Woelke and H.J. Loesch — Fakultät für Physik, Universität Bielefeld, 33615 Bielefeld, Germany
We present the results of crossed molecular beam experiments on the title reaction, were both Sr and ICl are in the ground state.
The spectra emitted by the electronically excited species have been measured over a wide range of collision energies 1.1 < Etr < 2.9 eV. The chemiluminescence is essentially due to the SrCl A and B states. Simulation calculations of the spectra indicate that the vibrational state population is essentially non-thermal and characterized by a rather narrow bell shaped curve centered around ν=13 ± 2. The SrCl C-state contributes less than 1% to the total light yield. The formation of excited SrI molecules is also not significant.
Using the brute force method to orient the ICl molecules we have measured the steric effect at a collision energy of Etr = 2.7 eV. The sign of the effect indicates that collisions with the Cl end lead preferentially to excited SrCl products. The results are consistent with a cone of non-acceptance whose full apex angle centered around the I-atom amounts to 92o.