title: First observation of HO˙ reactivity in water under high energy ions at elevated temperature.
abstract: This communication reports the first observation of the formation of HO˙ produced under two different High energy ion beams, (18)O(8+) and (36)Ar(18+) having Linear Energy Transfers (LET) of 65 and 350 eV nm(-1) respectively, at temperatures up to 411 K. Both scavenging with various concentrations of SCN(-) and heavy-ion pulse radiolysis methods are used with an original temperature and pressure regulated optical cell. Deconvolution of kinetics is used to analyze the evolution of HO˙ track segment yields as a function of time and temperature. It takes care of involving the ionic strength effect and Arrhenius expression in the rate constants correction. The results show a fast decay of HO˙ yields in the 10(-10)-10(-8) s range which denotes an efficient reactivity of this species in the track structure of the ion beam. This effect is enhanced with the lowest LET of O(8+). Increasing the temperature also accelerates the decays for both ions. These observations are discussed in terms of temperature activation of reactions and the track structure exhibiting the formation of HO˙ in a "low LET" penumbra around the ionization tracks. HO˙ track segment yields at 100 ns, of 0.4 × 10(-7) and 0.6 × 10(-7) mol J(-1), respectively for 350 and 65 eV nm(-1), are not affected by temperature.
authors.affiliation: CEA Saclay, IRAMIS, SIS2M, LRad, Bât 546, PC 175, F-91191 Gif-sur-Yvette Cedex, France. gerard.baldacchino@cea.fr.
authors.forename: A
authors.initials: A
authors.lastname: Balcerzyk
authors.forename: I
authors.initials: I
authors.lastname: Boughattas
authors.forename: S
authors.initials: S
authors.lastname: Pin
authors.forename: E
authors.initials: E
authors.lastname: Balanzat
authors.forename: G
authors.initials: G
authors.lastname: Baldacchino