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ABSTRACT: The multistate second order multiconfigurational perturbation theory in conjunction with spin-orbit interaction through complete active space state interaction (MS-CASPT2/CASSI-SO) was employed to calculate the potential energy curves for the ground and low-lying excited states of o-, m-, and p-iodotoluene along the assumed photolysis reaction coordinates. The mechanism and channels leading to products I((2)P(3/2)) and I( *)((2)P(3/2)) for o-, m-, and p-iodotoluene photolysis at 266 and 304 nm were elucidated with the computed potential energy curves and the surface crossing points. The effects of methyl substituent and heavy atom on the photodissociation mechanism were discussed by the comparison to related alkyl and aryl halides.
The Journal of chemical physics 01/2010; 132(1):014306. · 3.09 Impact Factor
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ABSTRACT: The photodissociations of o-, m-, and p-bromotoluene were investigated by ab initio and spin-orbit ab initio calculations. The possible photodissociation mechanisms at 266 and 193 nm were clarified by multistate second order multiconfigurational perturbation theory (MS-CASPT2) calculated potential energy curves, vertical excitation energies, and oscillator strengths of low-lying states. The dissociation products with spin-orbit-coupled states of Br(*)((2)P(12)) and Br((2)P(32)) were identified by the MS-CASPT2 method in conjunction with spin-orbit interaction through complete active space state interaction (MS-CASPT2/CASSI-SO) calculations. The effects of methyl rotation and substituent on the photodissociation mechanism were discussed.
The Journal of Chemical Physics 03/2008; 128(6):064307. · 3.33 Impact Factor
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ABSTRACT: Photodissociations of the o-, m-, and p-chlorotoluene at 193 and 266 nm were investigated by ab initio calculations with and without spin-orbit interaction. The experimentally observed photodissociation channels were clearly assigned by multistate second order multiconfigurational perturbation theory (MS-CASPT2) calculated potential energy curves. The dissociation products with spin-orbit-coupled states of Cl*(2P1/2) and Cl(2P3/2) were identified by MS-CASPT2 in conjunction with spin-orbit interaction through complete active space state interaction (MS-CASPT2/CASSI-SO) calculations. The effects of methyl rotation and substituent on the photodissociation mechanism were discussed in detail.
The Journal of Chemical Physics 08/2007; 127(4):044309. · 3.33 Impact Factor
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ABSTRACT: Photodissociation of aqueous formic acid has been investigated with the CASSCF, DFT, and MR-CI methods. Solvent effects are considered as a combination of the hydrogen-bonding interaction from explicit H2O molecules and the effects from the bulk surrounding H2O molecules using the polarizable continuum model. It is found that the hydrogen-bonding effect from the explicit water in the complex is the major factor to influence properties of aqueous formic acid, while the bulk surrounding H2O molecules has a noticeable influence on the structures of the complex. The direct C-O bond fission along the S1 pathway is predicted to be an important channel upon photolysis of aqueous formic acid at 200 nm, which is consistent with experimental observation that aqueous formic acid dissociates predominantly into fragments of HCO and OH. The existence of a dark channel upon photolysis of aqueous formic acid at 200 nm is assigned as fast relaxation from the S1 Franck-Condon geometry to the T1/S1 intersection and subsequent S1-->T1 intersystem crossing process. S1-->S0 internal conversion followed by molecular elimination to CO+H2O is the most probable primary process for formation of carbon monoxide, which was observed with considerable yield upon photolysis of aqueous formic acid at 253.7 nm.
The Journal of Physical Chemistry A 11/2006; 110(41):11704-10. · 2.95 Impact Factor
