Kuramochi Hikaru, Aoyama Genki, Okajima Hajime, Sakamoto Akira, Kanegawa Shinji, Sato Osamu, Takeuchi Satoshi, Tahara Tahei
Molecular Spectroscopy Laboratory, RIKEN, and, Ultrafast Spectroscopy Research Team, RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako, 351-0198, Japan.
JST, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan.
Angew Chem Int Ed Engl. 2020 Sep 7;59(37):15865-15869. doi: 10.1002/anie.202004583. Epub 2020 Jun 29.
Capability to control macroscopic molecular properties with external stimuli offers the possibility to exploit molecules as switching devices of various types. However, application of such molecular-level switching has often been limited by its speed and thus efficiency. Herein, we demonstrate ultrafast, photoinduced polarization switching in the crystal of a [CrCo] dinuclear complex by ultrafast pump-probe spectroscopy in the visible and mid-infrared regions. The photoinduced polarization switching was found to have a time constant of 280 fs, which makes the [CrCo] complex crystal the fastest polarization-switching material realized using the metastable state. Moreover, the pump-probe data in the visible region reveal the pronounced appearance of coherent nuclear wavepacket motion with a frequency as low as 22 cm , which we attribute to a lattice vibrational mode. The pronounced non-Condon effect for its resonance Raman enhancement implies that this mode couples the relevant electronic states, thereby facilitating the ultrafast polarization switching.
利用外部刺激控制宏观分子性质的能力为将分子用作各种类型的开关装置提供了可能性。然而，这种分子水平开关的应用常常受到其速度进而效率的限制。在此，我们通过可见和中红外区域的超快泵浦 - 探测光谱，在一种[CrCo]双核配合物晶体中展示了超快光致极化开关。发现光致极化开关具有280飞秒的时间常数，这使得[CrCo]配合物晶体成为利用亚稳态实现的最快的极化开关材料。此外，可见区域的泵浦 - 探测数据揭示了频率低至22厘米的相干核波包运动的显著出现，我们将其归因于晶格振动模式。其共振拉曼增强的显著非康登效应意味着该模式耦合了相关的电子态，从而促进了超快极化开关。
