Institute of Physical Chemistry, Christian-Albrechts-University Kiel, Olshausenstr. 40, 24098 Kiel, Germany.
Phys Chem Chem Phys. 2018 Aug 1;20(30):20033-20042. doi: 10.1039/c8cp02664e.
The photophysical dynamics of 2-aminopurine riboside (2APr) in CHCl3 have been studied following excitation at λpump = 310 nm by means of femtosecond transient vibrational absorption spectroscopy (TVAS) aided by quantum chemical density functional theory (DFT) and ab initio calculations. The experiments identified numerous vibrational marker bands in the regions of the NH2 stretch and the 2AP ring vibrations which could be assigned to the bleach of the S0 electronic ground state (GS) and to transient populations in the 1ππ* and 3ππ* excited electronic states. The temporal evolution of the transient vibrational bands shows that the decay of the 1ππ* population is accompanied by a partial recovery of the GS and a concurrent population of the 3ππ* state with a time constant of τ2 = 740 ± 15 ps. The ensuing electronic relaxation is concluded to proceed via the 1nπ* state as intermediate state. The absence of observable transient vibrational bands of this state hints at an upper limit for its lifetime of τ < 100 ps. The triplet quantum yield is found to be φT = 0.42 ± 0.07.
在 CHCl3 中，通过飞秒瞬态振动吸收光谱（TVAS）结合量子化学密度泛函理论（DFT）和从头算计算，研究了 2-氨基嘌呤核苷（2APr）在 λpump = 310nm 激发下的光物理动力学。实验在 NH2 伸缩和 2AP 环振动区域中确定了许多振动标记带，可以将其分配给 S0 电子基态（GS）的漂白和 1ππ和 3ππ激发电子态的瞬态布居。瞬变振动带的时间演化表明，1ππ布居的衰减伴随着 GS 的部分恢复和 3ππ态的同时布居，时间常数 τ2 = 740 ± 15 ps。随后的电子弛豫被认为是通过 1nπ*状态作为中间状态进行的。该状态不存在可观察到的瞬态振动带暗示其寿命上限为 τ < 100 ps。三重态量子产率被发现为 φT = 0.42 ± 0.07。
