Picosecond pulse radiolysis of highly concentrated sulfuric acid solutions: evidence for the oxidation reactivity of radical cation H2O(•+).
Aqueous solution of sulfuric acid is used as a suitable system to investigate the reactivity of the short-lived radical cation H2O(•+) which is generated by radiation in water. Ten aqueous solutions containing sulfuric acid with concentration from 1 to 18 mol L(-1) are studied by picosecond pulse radiolysis. The absorbance of the secondary radical SO4(•-) (or HSO4(•)) formed within the 10 ps electron pulse is measured by a pulse-probe method in the visible range. The analysis of the kinetics show that the radicals of sulfuric acid are formed within the picosecond electron pulse via two parallel mechanisms: direct electron detachment by the electron pulse and oxidation by the radical cation of water H2O(•+). In highly concentrated solution when SO4(2-) is in contact with H2O(•+), the electron transfer becomes competitive against proton transfer with another water molecule. Therefore, H2O(•+) may act as an extremely strong oxidant. The maximum radiolytic yield of scavenged H2O(•+) is estimated to be 5.3 ± 0.1 × 10(-7) mol J(-1).
Laboratoire de Chimie Physique, CNRS/Université Paris-Sud , Bât. 349, 91405 Orsay, France.
Jun
J
Ma
Uli
U
Schmidhammer
Mehran
M
Mostafavi
D004583:Electrons; D017665:Hydroxyl Radical / Q000737:chemistry*; D007700:Kinetics; D007834:Lasers; D010084:Oxidation-Reduction; D011675:Pulse Radiolysis; D012996:Solutions; D013464:Sulfuric Acids / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
D012996:Solutions; D013464:Sulfuric Acids; D014867:Water; D017665:Hydroxyl Radical; C033158:sulfuric acid