La Rivista del Nuovo Cimento (1978-1999)

, Volume 6, Issue 8, pp 1–72

Nonlinear laser photophysics, photochemistry and photobiology of nucleic acids

  • D. N. Nikogosyan
  • V. S. Letokhov
Article

DOI: 10.1007/BF02740898

Cite this article as:
Nikogosyan, D.N. & Letokhov, V.S. Riv. Nuovo Cim. (1983) 6: 1. doi:10.1007/BF02740898

Conclusion

The present paper is concerned with photophysics, photochemistry and photobiology of nucleic-acid molecules and their components under intense laser UV irradiation. Attempts have been made to follow the effect of nonlinear two-quantum excitation on the course of subsequent physical-chemical and biological processes. It has been shown that high-intensity laser UV irradiation of nucleic-acid molecules and their components with nanosecond and picosecond pulses enables us to realize two-step excitation of chromophorebases above the ionization limit. At the same time in some cases two-photon excitation of the solvent, water, forming reactive products occurs. Nonlinear two-quantum excitation of biomolecules and water provides realization of chemical reactions with the dissolved molecules participating, and the products of such reactions differ qualitatively from those of classical linear photochemistry. Besides, as the irradiation intensity increases, the quantitative relation between one-step and two-step nucleic-acid lesions changes, since the quantum yield of one-step lesions drops with increasing intensity and the quantum yield of two-step lesions increases. The products formed in nonlinear photochemical reactions may be important in biology. As a result, the biological processes after nonlinear excitation also begin to depend on intensity, which is illustrated in some instances in the last section of the paper. Thus the nonlinearity of the process of excitation of molecules under intense laser UV radiation (nonlinear photophysics) is responsible for the nonlinear character of subsequent chemical and biological processes (nonlinear photochemistry and photobiology).

Copyright information

© Società Italiana di Fisica 1983

Authors and Affiliations

  • D. N. Nikogosyan
    • 1
  • V. S. Letokhov
    • 1
  1. 1.Institute of SpectroscopyUSSR Academy of SciencesMoscow RegionUSSR