Radiation Response of Hydrated Urea Evaluated Using ¹⁴N Nuclear Quadrupole Resonance

Nitrogen-14 nuclear quadrupole resonance is utilized to detect radiation-induced changes in urea over the 0- to 300-Gy dose range. The spin-spin relaxation time exhibits a consistent change as a function of delivered dose in hydrated urea under exposure to ⁶⁰Co gamma radiation. No changes to the spin-spin relaxation time are observed in urea samples that were not hydrated. The radiation-induced changes are attributed to indirect radiation interactions with the water surrounding the urea molecules and are explained by the formation of subtle changes in the electron bonding configurations surrounding the ¹⁴N nuclei, not major structural rearrangements. These subtle changes may provide additional insight into the effects of ionizing radiation on biological systems.