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MO: Molekülphysik

MO 7: Poster: Cluster, Stoßprozesse

MO 7.24: Poster

Tuesday, March 17, 1998, 16:00–18:00, PF

Laser-induced fluorescence studies of excited Sr reactions with fluorine containing molecules — •S. Stolte, J.M. Teule, J. Mes, and M.H.M. Janssen — Dept. of Chemistry, Laser Centre, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands

We report measurements of reactions Sr (3P1) + RF & SrF (X2S) + R, where R is H, CH3, C2H5, C2H4F,C2H3, C2H2F or C6H5. The strontium atoms are excited to the 3P1-state using 689 nm light from a frequency-stabilized linear Ti:Sapphire laser. SrF formed in a beam-gas arrangement is detected via LIF using a CW dye laser as excitation source. The reaction of HF with Sr (1S0) is endothermic, and the metal is excited to allow the reaction to take place. The available energy is distributed over the relative translation of the products, and the vibration and rotation of the SrF product. The light H atom is observed to be ejected with high translational energy. Furthermore, the SrF internal energydistribution measured via LIF depends strongly on the impact parameter of the reaction.It is shown that the size and configuration of the alkyl group R in the other reactions influences the energy disposal mechanism. Part of the observations can be explained by the increased steric hindrance in the vicinity of the F atom for the larger molecules. The presence of a double bond in the molecular reactant seems to support an insertion mechanism, resulting in little vibrational excitation in the SrF product. Subtle differences are observed between reactions with several configurations of C2H2F2.