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The UV absorption of nucleobases: semi-classical ab initio spectra simulations

2010; Royal Society of Chemistry; Volume: 12; Issue: 19 Linguagem: Inglês

10.1039/b924956g

1463-9084

Mario Barbatti, Adélia J. A. Aquino, Hans Lischka,

Spectroscopy and Quantum Chemical Studies

Semi-classical simulations of the UV-photoabsorption cross sections of adenine, guanine, cytosine, thymine, and uracil in gas phase were performed at the resolution-of-identity coupled cluster to the second-order (RI-CC2) level. With the exception of cytosine, the spectra of the other four nucleobases show a two band pattern separated by a low intensity region. The spectrum of cytosine is shaped by a sequence of three bands of increasing intensity. The first band of guanine is composed by two ππ* transitions of similar intensities. The analysis of individual contributions to the spectra allows a detailed assignment of bands. It is shown that the semi-classical simulations are able to predict general features of the experimental spectra, including their absolute intensities.