Groupe en Sciences des Radiations, Département de Médecine Nucléaire et Radiobiologie, Faculté de Médecine et Sciences des radiations, Université de Sherbrooke, Québec J1H 5N4, Canada.
Phys Chem Chem Phys. 2020 Apr 29;22(16):8364-8372. doi: 10.1039/d0cp00198h.
Absolute cross sections (CSs) for electronic excitation by low-energy electron (LEE) scattering, from condensed thymidine (dT) in the 6-18 eV incident energy range, were measured by high-resolution electron energy loss spectroscopy (HREELS). Various electron energy loss (EEL) spectra were acquired using 1 ML of dT condensed on a multilayer film of Ar held at about 20 K under ultra-high vacuum (∼1 × 10-11 Torr). dT is one of the most complex DNA constituents to be studied by HREELS and these spectra provide the first LEE energy-loss data for electronic excitation of a nucleoside. CSs for transitions to the states 13A', 13A'', 23A', 21A', 33A', 23A'', 43A', 33A'', 53A' and 51A' of dT were extracted from the EEL spectra. These states correlate to those previously measured for the thymine moiety. Two broad resonances are observed in the energy dependence of the CSs at around 8 and 10 eV; these energies are close to those found in earlier gas- and solid-phase studies on the interaction of LEEs with dT, thymine and related molecules. A quantitative comparison between the electronic CSs of dT and those of thymine and tetrahydrofuran indicates that no variation is induced in the electronic CSs of thymine upon chemically binding to a deoxyribose group.
利用高分辨率电子能量损失谱（HREELS），测量了低能电子（LEE）散射引起的凝聚态胸腺嘧啶（dT）在 6-18 eV 入射能范围内的电子激发的绝对截面（CS）。使用在约 20 K 下的多层 Ar 膜上凝聚的 1 ML dT，获得了各种电子能量损失（EEL）谱，在超高真空（约 1×10-11 托）下。dT 是最复杂的 DNA 成分之一，通过 HREELS 进行研究，这些谱线提供了第一个核苷电子激发的 LEE 能量损失数据。从 EEL 谱中提取了 dT 的 13A'、13A''、23A'、21A'、33A'、23A''、43A'、33A''、53A'和 51A'态的 CSs。这些状态与先前测量的胸腺嘧啶部分相对应。在 CSs 的能量依赖性中观察到两个宽共振，约在 8 和 10 eV 左右；这些能量与 LEE 与 dT、胸腺嘧啶和相关分子相互作用的早期气相和固相研究中发现的能量接近。dT 的电子 CSs 与胸腺嘧啶和四氢呋喃的电子 CSs 的定量比较表明，当胸腺嘧啶化学结合到脱氧核糖基团上时，其电子 CSs 不会发生变化。
