Gd incorporated La-α-alanine complexes for radiation dosimetry: ESR and photoluminescence investigations

Recently, there has been a lot of interest in lanthanide-amino acid complexes. Especially, amino acid complexes with elements having high neutron absorption cross section like B, Cd, and rare earths such as Eu, Sm, Dy and Gd make them potential candidates as electron spin resonance (ESR) dosimetry. Through ESR dosimetric technique, identification and quantification of the radiation induced radicals can be achieved. Looking into the excellent properties of alanine complexes such as tissue equivalence, linear dose response and radical stability, alanine based ESR dosimetric technique has been recommended as a standard method by the International Atomic Energy Agency (IAEA). Further these complexes are also used as luminescent markers in various fluoroimmuno assay techniques. In all these applications, special emphasis has been given to understand the speciation of the rare earth species in the complex. In this context, ESR and photoluminescence (PL) investigations were carried out on Gd incorporated La-Alanine complexes. In addition to the virgin samples, gamma irradiated samples were also studied, to investigate the chemical nature of radiation induced radicals. Gamma irradiation of the sample was done in a 60Co gamma chamber