Ionic and tautomeric composition of cytosine in aqueous solution: resonance and non-resonance Raman spectroscopy study.

A complex experimental and theoretical study of the structural composition of cytosine in water was performed. Raman and resonance Raman spectra of cytosine in acidic, neutral, and alkaline water solutions (pH = 3, 7, and 10, respectively) were recorded at excitation wavelengths of 514, 266, 218, and 200 nm. The temperature dependence of the frequencies and intensities of the resonance Raman bands was obtained in the temperature interval of 4-80 °C.