Two-step picosecond UV excitation of polynucleotides and energy transfer |
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Authors: | D.N. Nikogosyan A.A. Oraevsky V.S. Letokhov Z.Kh. Arbieva E.N. Dobrov |
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Affiliation: | Institute of Spectroscopy, USSR Academy of Sciences, Troitzk, Moscow Region, 142092, USSR;A.N. Belozersky Laboratory of Molecular Biology, Moscow State University, Moscow 119899 USSR |
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Abstract: | We studied the dependence of the efficiency of two-step photoreactions in several polynucleotides: poly-U, Cspd-phage DNA and TMV RNA, on the chain length and spatial structure of the excited biopolymer under high-intensity picosecond UV irradiation (λ = 266nm, I = 1011 ?1014 W/m2, τp = 23 ps). It has been found that the effective energy transfer distance Λ in single-stranded polynucleotides is ≈ 1 or 2 nucleotides. In double-stranded nucleic acids Λ < 170. The lifetime τ1 of the excited electronic state S1 and the absorption cross section σ2 from the level S1 have been estimated for nucleotide pU (τ > 6.6 ps, σ2 <1.7 × 10?16 cm2). |
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Keywords: | To whom correspondence should be addressed. |
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