◆16-04 Surface Chemical Reaction Probed by X-ray Laser and Directed by Strong THz

• 日時：11/1（Tue.）16：30～17:30
• 場所：4号館2階輪講室 1+2
• 講師：小笠原寛人氏 (Staff Scientist, Stanford Synchrotron Radiation Lab.)
• 英題：Surface chemical reaction probed by x-ray laser and directed by strong THz
• 要旨:Catalysis at the solid surface is associated with challenging future chemical processes in chemical industry such as transforming CO₂ to fuels and nitrogen to ammonia using renewable resources. In catalysis at the solid surface driven by temperature, excitation of phonons as well as frustrated rotational and translational motions of reactant species play an important role. Recent ultrafast soft X-ray spectroscopy experiments using LCLS x-ray laser provided additional insights into this aspect [1-3], in which femtosecond visible laser pulse was used initiate reactions by producing high transient electronic temperatures followed by energy transfer to atomic and molecular motions. It would be highly desirable to drive chemical reactions by direct motional excitations on ultrafast timescales.

  We have recently demonstrated that the strong electric field of THz radiation from a linear accelerator can activate a chemical bond through electron migration near the Fermi level [4]. The study showed that the CO and O co-adsorbed system on Ru could be steered towards oxidation using the strong electric field of THz radiation, whereas CO desorption dominates in thermal and optical laser stimulated reactions. In the future, we propose to explore the possibility of steering a chemical reaction at the solid-liquid interface. Using the strong electric field of THz radiation, we intend to steer an electrochemical reaction through a migration of either electrons in the solid or ions in the liquid.

  
  [1] M. Dell'Angela et al., Science 339, 1302 (2013)
  [2] H. Öström et al., Science 347, 978 (2015)
  [3] M. Beye et al, J. Phys. Chem. Lett., 7, 3647 (2016)
  [4] J.L. LaRue et al, Phys. Rev. Lett. 115, 036103 (2015)