Excited state hydrogen transfer dynamics in substituted phenols and their complexes with ammonia: π π * -π σ*energy gap propensity and ortho-substitution effect

Lifetimes of the first electronic excited state (S1) of fluorine and methyl (o-, m-, and p-) substituted phenols and their complexes with one ammonia molecule have been measured for the 00 transition and for the intermolecular stretching σ1 levels in complexes using picosecond pump-probe spectroscopy. Excitation energies to the S1 (π π *) and S2 (π σ*) states are obtained by quantum chemical calculations at the MP2 and CC2 level using the aug-cc-pVDZ basis set for the ground-state and the S1 optimized geometries. The observed lifetimes and the energy gaps between the π π * and π σ* states show a good correlation, the lifetime being shorter for a smaller energy gap. This propensity suggests that the major dynamics in the excited state concerns an excited state hydrogen detachment or transfer (ESHD/T) promoted directly by a S1 / S2 conical intersection, rather than via internal conversion to the ground-state. A specific shortening of lifetime is found in the o-fluorophenol-ammonia complex and explained in terms of the vibronic coupling between the π π * and π σ* states occurring through the out-of-plane distortion of the C-F bond.Fil: Pino, Gustavo Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Oldani, Andres Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Marceca, Ernesto José. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Fujii, M.. Tokyo Institute of Technology; JapónFil: Ishiuchi, S.-I.. Tokyo Institute of Technology; JapónFil: Miyazaki, M.. Tokyo Institute of Technology; JapónFil: Broquier, M.. Centre National de la Recherche Scientifique; Francia. Universite Paris-Saclay;Fil: Dedonder, C.. Centre National de la Recherche Scientifique; Francia. Universite Paris-Saclay;Fil: Jouvet, C.. Universite Paris-Saclay; . Centre National de la Recherche Scientifique; Franci

Roadmap on dynamics of molecules and clusters in the gas phase

This roadmap article highlights recent advances, challenges and future prospects in studies of the dynamics of molecules and clusters in the gas phase. It comprises nineteen contributions by scientists with leading expertise in complementary experimental and theoretical techniques to probe the dynamics on timescales spanning twenty order of magnitudes, from attoseconds to minutes and beyond, and for systems ranging in complexity from the smallest (diatomic) molecules to clusters and nanoparticles. Combining some of these techniques opens up new avenues to unravel hitherto unexplored reaction pathways and mechanisms, and to establish their significance in, e.g. radiotherapy and radiation damage on the nanoscale, astrophysics, astrochemistry and atmospheric science

Collisional Broadening Coefficients in the ν4 Band of NH3 Perturbed by He and Ar

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IR-UV investigation of the structure of the 1-phenylethanol chromophore and its hydrated complexes

International audienc

Influence of complexation and solid environment on the vibrational coherence of DCl

The vibrational dynamics of DCl molecules embedded in different cryogenic matrices is studied by time resolved infrared Degenerate Four Wave Mixing experiments using the infrared free electron laser CLIO. The coherence behaviour of the D-Cl stretch in pure argon as well as in mixed argon/nitrogen van der Waals solids is investigated. Different interactions between the excited molecules and their environment are probed: the van der Waals interaction between the trapped molecules and the solid lattice and the interaction binding complexes trapped in the matrix (either the vdW interaction between DCl and nitrogen or weak H bonds in (DCl)n clusters). The dependence of the dephasing time on the solid and on specific interactions is clearly observed

Infrared spectra of the C2H2-HCl complexes: An experimental and ab-initio study

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Hydrogen-Bonded bridges in Complexes of o-Cyanophenol : Laser-Induced Fluorescence and IR/UV Double-Resonance Studies

International audienceThe o-cyanophenol molecule and its hydrogen-bonded complexes with one and two molecules of water and methanol have been investigated by laser-induced fluorescence excitation, dispersed emission, and IR/UV double-resonance spectroscopy combined with DFT calculations. The sole conformer observed in the jet has a cis geometry due to the stabilizing interaction between the OH and CN substituents. The shifts of the electronic transition and the modification of the OH ground-state frequencies together with the calculated geometry point to a cyclic structure of the complexes. In the 1:1 complexes, the solvent OH binds as a proton acceptor to the phenol OH and as a proton donor to the CN group. The 1:2 complexes involve in a similar way the insertion of the solvent dimer (water)2 or (methanol)2 between the OH and CN substituents of the molecule

Influence of a weak hydrogen bond on vibrational coherence probed by photon echoes in DCl dimer trapped in solid nitrogen.

International audienceThe dynamics in the ground electronic state of the two intramolecular D-Cl stretching modes of (DCl)2 in nitrogen solid has been probed by degenerate four wave mixing experiments. Accumulated photon echoes on the "free" nu1 and "bonded" nu2 modes have been performed by means of the free electron laser of Orsay (CLIO). The analysis of the time-resolved signals provides information on the various processes responsible for the loss of vibrational coherence, in particular intra- and intermolecular vibrational energy transfer and pure dephasing. The influence of the weak hydrogen bond is clearly observed on the coherence times of the two stretching modes. Whatever the temperature, the homogeneous width of nu2 lines is almost twice that of nu1 lines. Contrary to the case of isolated DCl trapped in solid nitrogen, no obvious effect of the nitrogen lattice can be extracted from the temperature dependence of the coherence times