title: H-bonded network rearrangements in the S0, S1 and D0 states of neutral and cationic p-cresol(H2O)(NH3) complexes.
abstract: The H-bonded network rearrangements in the S(0), S(1) and D(0) states of the neutral and cationic p-CreOH(H(2)O)(NH(3)) complexes were studied experimentally by means of (1 + 1)/(1 + 1') REMPI (Resonantly Enhanced MultiPhoton Ionization) and time resolved LIF (Laser Induced Fluorescence) spectroscopies combined with DFT (Density Functional Theory) calculations at the B3LYP/6-311G++(d,p) level. A comparison of the rearrangement process of the H-bonded network in the three states is given. Two cyclic H-bonded isomers were found on the S(0) potential energy surface and the results indicate that the rearrangement in this state is unlikely at the temperature of the supersonic expansion due to the presence of a high-energy barrier (7503 cm(-1)). On the other hand, the re-determination of the S(1) excited state lifetimes confirms that neither the H-bonded rearrangement nor the excited state hydrogen transfer (ESHT) reaction takes place in the S(1) state at the excitation energies of this work. Thus, it is concluded that the absorption of the second photon to reach the D(0) state takes place from the S(1) state of the cyclic-(OH-OH(2)-NH(3)) isomer. A preferential evaporation of H(2)O upon vertical ionization of the cyclic-(OH-OH(2)-NH(3)) isomer is observed which is consistent with a statistical redistribution of the internal energy. Nevertheless, our theoretical calculations suggest that initial excitation of the H-bonded network rearrangement modes may also play a role to leave the H(2)O molecule as a terminal moiety in a chain-(OH-NH(3)-OH(2))(+) isomer. The reaction pathway for the solvent rearrangement involves a double proton transfer process with a very low energy barrier (575 cm(-1)) that is overcome at the vertical ionization energy of the complex.
authors.affiliation: INFIQC, Dpto. de Fisicoquímica, Fac. de Ciencias Químicas, Centro Láser de Ciencias Moleculares, Universidad Nacional de Córdoba, Ciudad Universitaria, Pabellón Argentina, 5000 Córdoba, Argentina.
authors.forename: Federico J
authors.initials: FJ
authors.lastname: Hernández
authors.forename: Marcela C
authors.initials: MC
authors.lastname: Capello
authors.forename: Andrés N
authors.initials: AN
authors.lastname: Oldani
authors.forename: Juan C
authors.initials: JC
authors.lastname: Ferrero
authors.forename: Philippe
authors.initials: P
authors.lastname: Maitre
authors.forename: Gustavo A
authors.initials: GA
authors.lastname: Pino
mesh_terms: D000641:Ammonia / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D003408:Cresols / Q000737:chemistry*; D006860:Hydrogen Bonding; D007536:Isomerism; D008958:Models, Molecular; D011789:Quantum Theory
chemical_list: D002412:Cations; D003408:Cresols; C032538:4-cresol; D000641:Ammonia