On the photophysics and photochemistry of the water dimer

Journal Article · Fri Dec 28 00:00:00 EST 2012 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.4772187· OSTI ID:22099139

Segarra-Marti, Javier; Merchan, Manuela ^[1]; Roca-Sanjuan, Daniel; Lindh, Roland ^[2]

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1. Instituto de Ciencia Molecular, Universitat de Valencia, P.O. Box 22085, 46071 Valencia (Spain)
2. Department of Chemistry - Angstroem, Theoretical Chemistry Program, Uppsala University, Box 518, 75120 Uppsala (Sweden)

The photochemistry of the water dimer irradiated by UV light is studied by means of the complete active space perturbation theory//complete active space self-consistent field (CASPT2//CASSCF) method and accurate computational approaches like as minimum energy paths. Both electronic structure computations and ab initio molecular dynamics simulations are carried out. The results obtained show small shifts relative to a single water molecule on the vertical excitation energies of the dimer due to the hydrogen bond placed between the water donor (W{sub D}) and the water acceptor (W{sub A}). A red-shift and a blue-shift are predicted for the W{sub D} and W{sub A}, respectively, supporting previous theoretical and experimental results. The photoinduced chemistry of the water dimer is described as a process occurring between two single water molecules in which the effect of the hydrogen bond plays a minor role. Thus, the photoinduced decay routes correspond to two photodissociation processes, one for each water molecule. The proposed mechanism for the decay channels of the lowest-lying excited states of the system is established as the photochemical production of a hydrogen-bonded H{sub 2}O Horizontal-Ellipsis HO species plus a hydrogen H atom.

• OSTI ID: 22099139
• Journal Information: Journal of Chemical Physics, Vol. 137, Issue 24; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
DECAY
DIMERS
DISSOCIATION
ELECTRONIC STRUCTURE
EXCITATION
EXCITED STATES
HYDROGEN
HYDROGEN PRODUCTION
MOLECULAR DYNAMICS METHOD
MOLECULES
PERTURBATION THEORY
PHOTOCHEMISTRY
PHOTOLYSIS
RED SHIFT
SELF-CONSISTENT FIELD
SIMULATION
ULTRAVIOLET RADIATION
WATER