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Selective bond dissociation of HOD molecule by optimally designed polychromatic IR+UV pulse: a genetic-algorithm-based study
Published in Taylor and Francis Ltd.
Volume: 115
Pages: 1786 - 1796
A theoretical investigation of selective bond dissociation of O–H or O–D bond of HOD molecule is carried out by optimally designed electromagnetic field where optimisation is performed by Genetic Algorithm (GA). Two strategies depending upon the objective function and variable space for optimisation have been followed to achieve selective photodissociation. In Strategy I flux along a particular channel (JH + O-D/JD + O-H) in the repulsive excited state of HOD is considered in defining the objective function with a polychromatic IR pulse of eight components and a UV radiation of two components being optimally found out by GA. The polychromatic IR pulse distributes the population among the low quanta vibrational states of O–H or O–D stretching mode in ground electronic state and the subsequent UV pulse transfers the population to the excited state where photodissociation occurs. According to the direction of population along O–H or O–D stretch in ground electronic state, fluxes in the channels may be expected. We have obtained a maximum value of 92.38% and 74.12% along JH + O-D and JD + O-H channels, respectively. The Strategy II is the conventional strategy of selective vibrational excitation followed by population transfer to excited state by single UV pulse. In this case, the polychromatic IR fields are optimised by GA to achieve selective vibrational excitation on |1, 0⟩, |2, 0⟩, |0, 1⟩ and |0, 2⟩ states and the matching single UV pulse is fired for electronic excitation. The first two states correspond to the O–H stretch and population transfer from these states to excited state result in predominant flux along H+O–D channel and similar scheme from the last two states result in D+O–H dissociation as they are effectively of O–D character. The best values of JH + O-D and JD + O-H are 86.91% and 65.94% obtained by using Strategy II. © 2017 Informa UK Limited, trading as Taylor & Francis Group.
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JournalData powered by TypesetMolecular Physics
PublisherData powered by TypesetTaylor and Francis Ltd.