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Photoinduced Chemical Dynamics of High-Spin Alkali Trimers
1J. Higgins, C. Callegari, J. Reho, K. K. Lehmann, G. Scoles, Department of Chemistry, Princeton University, Princeton, NJ 08544, USA. F. Stienkemeier, Fakulat fur Physik, Universitat Bielefeld, D-33615, Bielefeld, Germany. W. E. Ernst, Department of Physics, Pennsylvania State University, University Park, PA 16802, USA. M. Gutowski, Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99352, USA, and Department of Chemistry, University of Gdansk, 80-952 Gdansk, Poland.
Abstract:
Nanometer-sized helium droplets, each containing about 10(4) helium atoms, were used as an inert substrate on which to form previously unobserved, spin-3/2 (quartet state) alkali trimers. Dispersed fluorescence measurements reveal that, upon electronic excitation, the quartet trimers undergo intersystem crossing to the doublet manifold, followed by dissociation of the doublet trimer into an atom and a covalently bound singlet dimer. As shown by this work, aggregates of spin-polarized alkali metals represent ideal species for the optical study of fundamental chemical dynamics processes including nonadiabatic spin conversion, change of bonding nature, and unimolecular dissociation.