Nonlinear laser photophysics, photochemistry and photobiology of nucleic acids
Nonlinear laser photophysics, photochemistry and photobiology of nucleic acids
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核酸的非线性激光光物理学、光化学和光生物学
DOI：
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发表时间：
1983
期刊：
影响因子：
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通讯作者：
V. Letokhov
中科院分区：
文献类型：
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作者：
D. N. Nikogosyan;V. Letokhov
结论本文涉及强激光紫外照射下核酸分子及其组分的光物理学、光化学和光生物学。人们尝试追踪非线性二量子激发对后续物理化学和生物过程的影响。研究表明，用纳秒和皮秒脉冲对核酸分子及其成分进行高强度激光紫外照射，使我们能够实现高于电离极限的发色基团的两步激发。在某些情况下同时双光子激发溶剂、水，形成反应产物。生物分子和水的非线性双量子激发实现了溶解分子参与的化学反应，这种反应的产物与经典线性光化学的产物有质的不同。此外，随着照射强度的增加，一步和两步核酸损伤之间的定量关系发生变化，因为一步损伤的量子产率随着强度的增加而下降，而两步损伤的量子产率增加。非线性光化学反应中形成的产物可能在生物学中很重要。因此，非线性激励后的生物过程也开始依赖于强度，这在本文最后一节的某些情况下进行了说明。因此，在强激光紫外辐射下分子激发过程的非线性（非线性光物理学）是导致后续化学和生物过程（非线性光化学和光生物学）的非线性特征的原因。
ConclusionThe 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).