The relaxation pathways of silyl-modified guanosine nucleoside monomers (G) and double-hydrogen-bonded homodimers (GG1) are compared in chloroform solution after 260-nm ultraviolet excitation. Transient absorption spectra support two previously reported relaxation pathways for the monomer with time constants of 210 ± 20 fs and 2.6 ± 0.1 ps. These pathways are associated with bifurcated approach to a seam of conical intersections between the excited ¹ππ∗ ¹L_a state and the ground electronic state. In the homodimer, an increase in the larger time constant to 18 ± 2 ps is attributed to slower passage through the minimum energy region of the ¹ππ∗ state. A further time constant of 70 ± 10 fs indicates wavepacket evolution out of the ¹ππ∗ state Franck-Condon region. A slow component of recovery of ground-state GG1 is proposed to result either from relaxation of the product of inter-base electron-driven proton transfer, or from the lowest triplet state (³ππ∗, T₁).

在260 nm紫外线激发后，在氯仿溶液中比较了甲硅烷基修饰的鸟苷核苷单体（G）和双氢键合同二聚体（GG1）的弛豫途径。瞬态吸收光谱支持两个先前报道的单体弛豫途径，其时间常数为210  ±  20 fs和2.6  ±  0.1 ps。这些通路与兴奋之间分叉的方法来圆锥交叉的接缝相关联的¹ ππ* ¹大号_一个状态和基态。在同型二聚体，以18个±2 PS的增加较大的时间常数是通过的最小能量区域归因于更慢的通道^1个ππ*状态。进一步的时间常数为70 ±  10个FS表示波包进化出的^1个ππ*状态弗兰克-康登区域。基态GG1的恢复的缓慢成分，提出了从基站间的电子驱动的质子转移，或者从最低三重态（的产物松弛要么导致³ ππ*，T ₁）。