Production of a fluorescence probe in ion-beam radiolysis of aqueous coumarin-3-carboxylic acid solution-1: Beam quality and concentration dependences

Aqueous coumarin-3-carboxylic acid (3-CCA) solutions were irradiated with seven different ion beams covering LET range from 0.5 to above 2000 eV/nm. G-values of 70H-CCA, one of hydroxylated products in radiolysis of the solutions, have been determined by fluorescence-HPLC technique in 3-CCA concentration range from 0.1 to 26 mM. The formation yield of 70H-CCA increased with increase in concentration of 3-CCA while it decreased with increase in LET value of ion beam. Compared with our previous reports on G((OH)-O-center dot) at a scavenging capacity of 10(7) s(-1) with absorption spectroscopy, it was found that G(7OH-CCA) is about (4.7 +/- 0.6)% of G((OH)-O-center dot), which is consistent for all of the ion beams used in the present study. However, 7OH-CCA yields in high 3-CCA concentration region, especially by using extremely high LET ions, were much higher than expected values based on the above conversion factor and G(OH) value predicted in theoretical work. (C) 2010 Elsevier Ltd. All rights reserved.