论文部分内容阅读
DNA及其组分由于激发态量子产额低，其激发三重态的研究遇到很大困难。直到本世纪九十年代，中国科学院辐射化学开放实验室采用丙酮敏化激发以增大其三重态量子产额方法，相继得到DNA除胸腺嘧啶外的其它三个碱基及其衍生物的激发三重态吸收光谱及其衰减动力学常数。然而，这种敏化激发的方法是否与直接激发所得到的结果一致，还没有这方面的研究报道。本研究采用纳秒级激光光解瞬态吸收光谱法研究了胸腺嘧啶及其核苷、核苷酸的激光直接激发和丙酮敏化光解，同时得到两种研究方法的胸腺嘧啶及其核苷、核苷酸三重态的单分子衰减常数（ko）和被其基态的自猝灭常数（Ksp），其中胸腺嘧啶、胸苷的丙酮敏化结果和胸腺嘧啶、胸苷酸的直接激发结果均是首次得到的。从两种方法得到的数据看，它们的偏差在实验误差范围内，因而两种方法得到的结果是一致的。并且，由于丙酮敏化所得到的三重态量子产额高，因而其瞬态吸收谱的信号强、测量精度高。故可认为丙酮敏化方法得到的结果更真实可靠。
Due to the low quantum yield of the excited state DNA and its components, it is very difficult to study triplex excitation. Until the 1990s, the Chinese Academy of Sciences Laboratory of Radiation Chemistry using acetone-sensitized excitation to increase its triplet quantum yield method, have been obtained in addition to DNA thymine three other bases and their derivatives excited triple Absorption spectra and their decay kinetic constants. However, whether this method of sensitization excitation is consistent with the result obtained by direct excitation has not been reported in this aspect. In this study, nanosecond laser photolysis transient absorption spectroscopy was used to study thymidine and its nucleosides, direct laser excitation of nucleotides and acetone-sensitized photolysis. At the same time, two methods of thymine and its nucleosides , Single-molecule decay constant (ko) of nucleotide triplet state and self-quenching constant (Ksp) determined by its ground state, and the results of acetone sensitization of thymidine and thymidine and direct excitation of thymidine and thymidylate For the first time. Judging from the data obtained by the two methods, their deviations are within the experimental error range, so the results obtained by the two methods are consistent. Moreover, since the triplet quantum yield obtained by acetone sensitization is high, the signal of the transient absorption spectrum is strong, and the measurement accuracy is high. Therefore, the results obtained by the acetone sensitization method can be considered more realistic and reliable.