Dense radical formation in L-alanine-3,3,3-d3 and L-alanine-d4 by 1.5 keV soft X-ray irradiation

Radicals produced in crystalline L-alanine-3,3,3-d3 and L-alanine-d4 were observed by the electron spin reso-nance (ESR) technique during 1.5 keV soft X-ray irradiation. The spectral change from •CHCD3COOH to •CDCD3COOH by a hydrogen exchange reaction was directly observed in L-alanine-3,3,3-d3. The line width of the ESR spectra obtained by the soft X-ray irradiation was 1.5 times wider than that of hard X-rays from a previous report, meaning a higher density of radicals