Injection of photoexcited electrons in the para-Ethyl Red dye to TiO₂ nanoparticles (Anatase, 40 nm diameter) is characterized by transient absorption on ultrafast time scales. This study focuses on understanding the effect of aprotic solvents on the injection rate. Transient absorption at 1900 cm⁻¹ is probed following a 400 nm pulse which excites the electronic transition of p-ER adsorbed on TiO₂ through its carboxylic group. Measurements conducted in three different solvents show that electron injection lifetimes are in the 250–300 fs range but display a trend in correlation with solvent polarity: the electron injection lifetime is the shortest (257 fs) in acetonitrile followed by dichloromethane (271 fs) and chloroform (296 fs). This trend can be understood by using the Marcus theory in which the reorganization energy varies correspondingly in the three different solvents. This study shows that for aprotic solvents the one with the highest polarity facilitates the fastest electron injection.

将对乙基红染料中的光激发电子注入TiO ₂纳米颗粒（锐钛矿，直径40 nm）的特征在于超快时间尺度上的瞬态吸收。这项研究的重点是了解非质子溶剂对注射速率的影响。在400 nm脉冲后探测1900 cm ^-1处的瞬态吸收，该脉冲激发TiO _2上吸附的p-ER的电子跃迁通过其羧基。在三种不同溶剂中进行的测量表明，电子注入寿命在250–300 fs范围内，但显示出与溶剂极性相关的趋势：电子注入寿命是乙腈中最短的（257 fs），其次是二氯甲烷（271 fs）和乙腈。氯仿（296 fs）。可以通过使用Marcus理论来理解这种趋势，在该理论中，重组能量在三种不同的溶剂中会相应地变化。这项研究表明，对于非质子传递溶剂，极性最高的溶剂有助于最快的电子注入。