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    A pair potentials study of matrix-isolated atomic zinc. I. Excited 1P1 state dynamics in solid Ar


    Kerins, P.N. and McCaffrey, John G. (1998) A pair potentials study of matrix-isolated atomic zinc. I. Excited 1P1 state dynamics in solid Ar. Journal of Chemical Physics, 109 (8). pp. 3131-3136. ISSN 0021-9606

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    Abstract

    The pair-potentials calculations of McCaffrey and Kerins [J. Chem. Phys. 106, 7885 (1997)] used with success in simulating the emission spectroscopy of the Zn–RG matrix systems are extended to examine the different temporal decay characteristics exhibited at low temperature, T<13 K, by the singlet emission bands in the Zn–Ar matrix system. The 238 nm band, assigned in the earlier theoretical work to the body mode Q2, exhibits a 0.1 ns risetime, the 219 nm band assigned to the waist mode Q3, is prompt. By extracting the gradients and the second derivatives of the Q3 and Q2 mode potentials of a Zn⋅Ar18 cluster, decay rates of 3 and 2 ps, respectively, are calculated at the Franck–Condon regions of these potentials accessed in absorption, leading to effective competition between the Q2 and Q3 modes for relaxation of excited-state population and thereby to the coexistence of the 238 nm emission with the 219 nm band. A quasi-bound region is located at 0.32 Å in the body mode, Q2, which slows down the relaxation on this mode and is identified as responsible for the recorded risetime on the 238 nm emission. The temperature dependence exhibited in the Zn–Ar system at higher temperatures (T>14 K) in which the intensity of the 219 nm band can reversibly be put into the 238 nm band, was examined by generating the (PES) potential-energy surface for coupled Q2×Q3 vibronic modes. The theoretically predicted activation energy barrier is 380 cm−1, which is only in qualitative agreement with the value of 130.6 cm−1 extracted in the kinetics study. Possible reasons for the overestimation in the theoretical value are discussed.

    Item Type: Article
    Keywords: Excited states; Kinetic theory; Activation energies; Zinc; Emission spectroscopy;
    Academic Unit: Faculty of Science and Engineering > Chemistry
    Item ID: 7861
    Identification Number: https://doi.org/10.1063/1.476904
    Depositing User: Dr. John McCaffrey
    Date Deposited: 03 Feb 2017 17:12
    Journal or Publication Title: Journal of Chemical Physics
    Publisher: American Institute of Physics
    Refereed: Yes
    URI:

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