Nitrogen dioxide (NO2) created by gamma-rays in Antarctic ice and rime ice.

Antarctic ice and rime ice after gamma-irradiation at 77 K were studied by electron spin resonance (ESR). The signal of nitrogen dioxide (NO2) was detected in both ices. The NO2 in the Antarctic ice, in particular, may be created from NO3- by reactions associated with intrinsic OH radicals. The detection limit of NO2 in solid samples was estimated to be approximately 0.02 ppm with ESR. The analysis using ESR in natural ice has a potential to trace environmental NO2.