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AMPD: EPS AMPD
AMPD 4: Sitzung 4
AMPD 4.4: Vortrag
Dienstag, 3. April 2001, 11:55–12:20, H104
ANGULAR MOMENTUM PROPERTIES OF ATOMIC PHOTOFRAGMENTS FOLLOWING PHOTODISSOCIATION — •O.S. Vasyutinskii1, J.A. Beswick2, A.G. Suits3, and D. Zimmermann4 — 1Ioffe Institute, Russian Academy of Sciences, 194021 St.Petersburg, Russia — 2IRSAMC , Universite Paul Sabatier, 118 rte de Narbonne, 31062 Toulouse, France — 3Department of Chemistry, State University of New York at Stony Brook, Stony Brook, NY 11794, USA — 4Institut für Atomare und Analytische Physik,Technische Universität Berlin, D-10623 Berlin, Germany
Recent investigations have demonstrated that experiments that can measure the angular distribution of angular momentum polarization in atomic photofragments can yield insight into the photodissociation dynamics of environmental molecules in the molecular frame. The experiments have led to observation of a series of remarkable new phenomena, some of which are still far from being understood. These include: unexpectedly high photofragment alignment observed in photodissociation of diatomic and especially three–atomic molecules, observation of a pure quantum mechanical coherent dissociation mechanism of atomic photofragment alignment, and observation of energy–dependent quantum oscillations in the cross section of photofragment orientation.
A rigorous theoretical connection is established between experimental measurements of the photofragment orientation and alignment and the underlying photodissociation dynamics. Laboratory and molecular–frame angular momentum state multipoles are derived as a function of photofragment recoil angles. These state multipoles are expressed in terms of orientation and alignment anisotropy parameters, which contain information on excited state symmetries, coherence effects, and nonadiabatic interactions. To show the power of the theoretical method, it is applied to experimental data obtained with velocity map ion imaging in both diatomic (Cl2) and polyatomic systems (NO2 and N2O) and with Doppler Faraday technique in (RbI). Strong recoil–frame alignment and orientation has been observed, as well as coherence effects and long-range nonadiabatic interactions. The goal of the current report is to give an overview of some of the obtained experimental and theoretical results and to show the perspectives for further studies.
ACKNOWLEDGEMENTS This work was supported by INTAS under Award # 97–31573.
[1] K.O. Korovin, B.V. Picheyev, O.S.Vasyutinskii, H. Valipour, D.Zimmermann, J. Chem. Phys. 112, N 5, 2059 (2000).
[2] E.R. Wouters, M. Ahmed, D.S. Peterka, A.S. Bracker, A.G. Suits, O.S.Vasyutinskii in Imaging in Chemical Dynamics, A. G. Suits and R.E.Continetti, eds., ACS Symposium Series, (American Chemical Society,Washington DC, 2000, p. 238 – 284).