title: Photochemistry of CH3Cl: Dissociation and CH···Cl Hydrogen Bond Formation.
abstract: State-of-the-art electronic structure calculations (MR-CISD) are used to map five different dissociation channels of CH3Cl along the C-Cl coordinate: (i) CH3(X̃(2)A2″) + Cl((2)P), (ii) CH3(3s(2)A1') + Cl((2)P), (iii) CH3(+)((1)A1') + Cl(-)((1)S), (iv) CH3(3p(2)E') + Cl((2)P), and (v) CH3(3p(2)A2″) + Cl((2)P). By the first time these latter four dissociation channels, accessible upon VUV absorption, are described. The corresponding dissociation limits, obtained at the MR-CISD+Q level, are 3.70, 9.50, 10.08, 10.76, and 11.01 eV. The first channel can be accessed through nσ* and n3s states, while the second channel can be accessed through n(e)3s, n(e)3p(σ), and σ3s states. The third channel, corresponding to the CH3(+) + Cl(-) ion-pair, is accessed through n(e)3p(e) states. The fourth is accessed through n(e)3p(e), n(e)3p(σ), and σ3p(σ), while the fifth through σ3p(e) and σ(CH)σ* states. The population of the diverse channels is controlled by two geometrical spots, where intersections between multiple states allow a cascade of nonadiabatic events. The ion-pair dissociation occurs through formation of CH3(+)···Cl(-)and H2CH(+)···Cl(-) intermediate complexes bound by 3.69 and 4.65 eV. The enhanced stability of the H2CH(+)···Cl(-) complex is due to a CH···Cl hydrogen bond. A time-resolved spectroscopic setup is proposed to detect those complexes.
authors.affiliation: Departamento de Química, CCEN, Universidade Federal da Paraíba , João Pessoa, PB 58059-900, Brazil.
authors.forename: Vanessa C
authors.initials: VC
authors.lastname: de Medeiros
authors.affiliation: Departamento de Química, CCEN, Universidade Federal da Paraíba , João Pessoa, PB 58059-900, Brazil.
authors.forename: Railton B
authors.initials: RB
authors.lastname: de Andrade
authors.affiliation: Departamento de Química, CCEN, Universidade Federal da Paraíba , João Pessoa, PB 58059-900, Brazil.
authors.forename: Ezequiel F V
authors.initials: EF
authors.lastname: Leitão
authors.affiliation: Departamento de Química, CCEN, Universidade Federal da Paraíba , João Pessoa, PB 58059-900, Brazil.
authors.forename: Elizete
authors.initials: E
authors.lastname: Ventura
authors.affiliation: Departamento de Química, Instituto de Ciências Exatas, UFRRJ, Pavilhão Roberto Alvahydo (PQ) , sala 44. km 7, Rodovia Br 465, Seropédica, RJ 23890-000, Brazil.
authors.forename: Glauco F
authors.initials: GF
authors.lastname: Bauerfeldt
authors.affiliation: Aix Marseille Université , CNRS, ICR UMR7273, 13397 Marseille, France.
authors.forename: Mario
authors.initials: M
authors.lastname: Barbatti
authors.affiliation: Departamento de Química, CCEN, Universidade Federal da Paraíba , João Pessoa, PB 58059-900, Brazil.
authors.forename: Silmar A
authors.initials: SA
authors.lastname: do Monte