Toyota Physical and Chemical Research Institute, Nagakute, Aichi 480-1192, Japan.
J Phys Chem A. 2013 Sep 5;117(35):8352-9. doi: 10.1021/jp402194g. Epub 2013 Aug 22.
Ytterbium 3+ ions in alcohol were found to be reduced to the corresponding 2+ ions upon laser irradiation with a stepwise two-color two-photon excitation. The infrared (975-nm) pulse with a duration of 4 ns pumps the ground state to the 4f excited state with the transition of (2)F(5/2) ← (2)F(7/2), and the second photon (355-nm) generates the charge transfer (CT) state of Cl 3p to Yb 4f; the reduction then occurs. Laser energy and excitation wavelength dependencies well-explain the above mechanism. The product Yb(2+) was detected by its absorption spectrum peak at 367 nm. The absorption spectrum of the intermediate in the two-photon chemistry was measured from the 4f excited state ((2)F(5/2)) to the CT state by nanosecond laser photolysis. The intermediate spectrum appears in the wavelengths shorter than 400 nm with the molar extinction coefficient on the order of (10(2) M(-1) cm(-1)) at 340 nm and can be explained in terms of the CT absorption shifted by IR photon energy. A UV nanosecond laser pulse (266 nm from a YAG laser with a duration of 6 ns) can generate the reactive CT state by one-photon absorption and leads to Yb(2+) formation. The reaction yields for single-photon UV excitation and the second photon in the two-photon excitation are on the order of 0.1, suggesting that the reactive states are a common CT state.
在激光辐照下，镱 3+ 离子在醇中被还原为相应的 2+ 离子，这是通过逐步双色双光子激发实现的。持续时间为 4 ns 的红外（975nm）脉冲将基态泵浦到 4f 激发态，跃迁为 (2)F(5/2) ← (2)F(7/2)，第二光子（355nm）产生 Cl 3p 到 Yb 4f 的电荷转移（CT）态；然后发生还原。激光能量和激发波长的依赖性很好地解释了上述机制。通过吸收光谱在 367nm 处检测到产物 Yb(2+)。通过纳秒激光光解从 4f 激发态 ((2)F(5/2)) 到 CT 态测量了双光子化学中的中间产物的吸收光谱。中间光谱出现在 400nm 以下的波长范围内，在 340nm 处的摩尔消光系数约为 (10(2) M(-1) cm(-1))，可以用 IR 光子能量移动的 CT 吸收来解释。一个纳秒紫外激光脉冲（来自 YAG 激光的 266nm，持续时间为 6ns）可以通过单光子吸收产生反应性 CT 态，并导致 Yb(2+)的形成。单光子 UV 激发和双光子激发中的第二光子的反应产率约为 0.1，表明反应态是一种常见的 CT 态。
