Thøgersen Jan, Weidner Tobias, Jensen Frank
Dept. of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark.
Phys Chem Chem Phys. 2021 Apr 28;23(16):10040-10050. doi: 10.1039/d1cp00205h.
We study the primary reaction dynamics of aqueous oxalate following photo-excitation of the nO → πCO* transition at λ = 200 nm. After the excitation, some of the oxalate molecules return to the electronic ground state on two very different time scales: a fast component of τ = 1.1 ± 0.5 ps comprising 40% of the excited molecules and a much slower component of τ = 0.28 ± 0.05 ns accounting for 15% of the excited molecules. The remaining 45% of the excited molecules do not return to the ground state during the first 500 ps, because they either detach an electron, dissociate or stay excited for hundreds of picoseconds. Dissociation and electron detachment of oxalate predominantly produces CO2 molecules with only minor yields of CO2˙- radical anions. The CO2 formation is accompanied by the ejection of electrons.
我们研究了在λ = 200 nm处nO → πCO*跃迁光激发后草酸盐水溶液的初级反应动力学。激发后，一些草酸分子在两个非常不同的时间尺度上回到电子基态：一个快速成分，τ = 1.1 ± 0.5 ps，占激发分子的40%；一个慢得多的成分，τ = 0.28 ± 0.05 ns，占激发分子的15%。其余45%的激发分子在前500 ps内没有回到基态，因为它们要么脱离一个电子、解离，要么在数百皮秒内保持激发态。草酸的解离和电子脱离主要产生CO2分子，只有少量的CO2˙-自由基阴离子生成。CO2的形成伴随着电子的射出。
