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component gives (3 "'" 0.0. A detailed discussion of the results in terms of electronic structure, photofragmentation dynamics, and allowed electronic transitions, concludes that Ar 3+ takes the form of a stable dimer ion and a weakly bound atom, and that it is most probably nonlinear.7612

A supersonic nozzle has been used to generate Ar2+ in the ion source of a mass spectrometer via the electron impact ionization of neutral dimers and clusters. Following mass selection, the dimer ion has been photodissociated with infrared radiation from a C02 laser in a crossed-beam configuration. By changing the plane of polarization of the laser radiation, two electronic transitions have been identified. One transition corresponds to excitation to a repulsive state, a process that has been established from previous photodissociation studies using visible radiation. It is proposed that the second transition is associated with excitation to quasibound levels in a shallow ion-induced-dipole well, situated in the long-range region of an otherwise repulsive electronic state.

agreement with other experimental values for the diffusion coefficient in bilayer aggregates.34 The values of R («25 A) are comparable to the values of ~15 A for quenching of hydrocarbon fluorescence by perfluorocarbons in bulk solution; they are too large, but of the right order of magnitude. Is is possible that the origin of these large values of R lies in the fact that the motion of our small fluorophore and quencher molecules is not unrestricted in three dimensions but is somewhere between strictly lateral20 and fully 3-D. Some authors40 have assigned values of R in order to calculate D, apparently because of this difficulty. We have chosen not to follow this procedure in this work.