title: Double deuterated acetylacetone in neon matrices: infrared spectroscopy, photoreactivity and the tunneling process.
abstract: The effect of deuteration of acetylacetone (C5O2H8) is explored by means of IR spectroscopy of its single and double deuterated isotopologues trapped in neon matrices. The whole vibrational spectra of chelated enols are very sensitive to the H-D exchange of the hydrogen atom involved in the internal hydrogen bond. UV excitation of double deuterated acetylacetone isolated in neon matrices induces the formation of four open enol isomers which can be divided into two groups of two conformers, depending on their formation kinetics. Within each group, one conformer is more stable than the other: slow conformer interconversion due to a tunneling process is observed in the dark at low temperature. Moreover, IR laser irradiation at the OD stretching overtone frequency is used to induce interconversion either from the most stable to the less stable conformer or the opposite, depending on the excitation wavelength. The interconversion process is of great help to assign conformers which are definitively identified by comparison between experimental and calculated IR spectra. Kinetic constants of the tunneling process at play are theoretically estimated and agree perfectly with experiments, including previous experiments with the totally hydrogenated acetylacetone [Lozada García et al., Phys. Chem. Chem. Phys., 2012, 14, 3450].
authors.affiliation: Institut des Sciences Moléculaires d'Orsay (ISMO), Bât.210, UMR 8214, CNRS, Univ. Paris-Sud 11, Université Paris-Saclay, F-91405 Orsay Cedex, France. alejandro.gutierrez-quintanilla@u-psud.fr and Instituto Superior de Tecnologías y Ciencias Aplicadas, La Habana, Cuba.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Gutiérrez-Quintanilla
authors.affiliation: Institut des Sciences Moléculaires d'Orsay (ISMO), Bât.210, UMR 8214, CNRS, Univ. Paris-Sud 11, Université Paris-Saclay, F-91405 Orsay Cedex, France. alejandro.gutierrez-quintanilla@u-psud.fr.
authors.forename: Michèle
authors.initials: M
authors.lastname: Chevalier
authors.affiliation: Institut des Sciences Moléculaires d'Orsay (ISMO), Bât.210, UMR 8214, CNRS, Univ. Paris-Sud 11, Université Paris-Saclay, F-91405 Orsay Cedex, France. alejandro.gutierrez-quintanilla@u-psud.fr.
authors.forename: Claudine
authors.initials: C
authors.lastname: Crépin