Oxidation of bromide ions by hydroxyl radicals: Spectral characterization of the intermediate BrOH^•-

Isabelle Lampre (1) , Jean-Louis Marignier (1) , Malaknaz Mirdamadi-Esfahani (1) , Pascal Pernot (1) , Pierre Archirel (1) , Mehran Mostafavi (1)

1 LCPO - Laboratoire de Chimie Physique D'Orsay

The reaction of •OH with Br- has been reinvestigated by picosecond pulse radiolysis combined with streak camera absorption detection and the obtained spectro-kinetics data have been globally analyzed using Bayesian data analysis. For the first time, the absorption spectrum of the intermediate species BrOH•- has been determined. This species absorbs in the same spectral domain as Br2 •-: the band maximum is roughly at the same wavelength (λmax = 352 nm instead of 354 nm) but the extinction coefficient is smaller (εmax = 7800 ± 400 dm3 mol-1 cm-1 compared with 9600 ± 300 dm3 mol-1 cm-1) and the band is broader (88 nm versus 76 nm). Quantum chemical calculations have also been performed and corroborate the experimental results. In contrast to Br2•-, the existence of several water-BrOH•- configurations leading to different transition energies may account for the broadening of the absorption spectrum in addition to the higher number of degrees of freedom. © 2013 American Chemical Society.

Mots clés: water; reactivity; reduction; electrons; hydroxyl radicals; spectral domains; quantum chemical calculations; bayesian data analysis; transition energy; spectral characterization; extinction coefficients; number of degrees of freedom; picosecond pulse radiolysis; intermediate specie; bromide ions; solvation dynamics; aqueous-solutions; pulse-radiolysis; 2-photon ionization; liquid polyols; earth alkaline-metals

Domaines: Chimie

Isabelle Lampre, Jean-Louis Marignier, Malaknaz Mirdamadi-Esfahani, Pascal Pernot, Pierre Archirel, et al.. Oxidation of bromide ions by hydroxyl radicals: Spectral characterization of the intermediate BrOH^•-. Journal of Physical Chemistry A, 2013, ⟨10.1021/jp310759u⟩. ⟨hal-04037324⟩