Total-ion-yield near-edge X-ray absorption fine structure spectra of pyrimidine nucleobases were recorded. The phenomenon of specific dissociation, such as a larger branching ratio of some ionic fragments at a resonant excitation energy, was observed. From the details of the specific dissociation channels of pyrimidine nucleobases, the larger branching yields of some fragment ions at π*-resonant excitations indicate that a local bond cleavage around the atom excited is responsible for producing these ions; local excitation thus plays a major role in the site-specific dissociations. Using the NEXAFS spectra, representative ions and their branching ratios, we propose some improved ways to determine the quantities of pyrimidine nucleobases in DNA and RNA instead of only product masses or NEXAFS spectra.

Specific dissociation of core-excited pyrimidine nucleobases

256th National Meeting (2018)

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