Ultrafast Spectroscopy Research Team

Team Leader

Tahei Tahara


Tahei Tahara


Access map

tahei [at] riken.jp

Ultrafast Spectroscopy Research Team,
RIKEN Center for Advanced Photonics

2-1 Hirosawa, Wako, Saitama 351-0198 Japan

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We are developing "femtosecond time-resolved impulsive Raman spectroscopy" (femtosecond is 10-15 second), which enables tracking structural change of the reacting molecule through direct observation of the nuclear motion. Using this method, we successfully elucidated the first event occurring in a photoreceptor protein "Photoactive Yellow Protein (PYP)" which stimulates bacteria to escape from the harmful light under light irradiation. We first irradiated PYP with blue light and then shook PYP for observing the nuclear motion moment by moment, like taking "stroboscopic photographs". It was revealed that within only 10 trillionths of a second (10-13 seconds) from the irradiation of blue light, specific hydrogen bonds near the light-absorbing site weakened, and then carbon - carbon double bond rotated, generating a peculiar distorted structure. This is a breakthrough achievement that tracks elaborate mechanisms for proteins to start functioning in real time.


Chemistry, Physics, Biology / Biochemistry


Ultrafast spectroscopy, Nonlinear spectroscopy, Single molecule spectroscopy, Dynamics, Interface


  1. Generation of ultrashort pules and development of ultrafast spectroscopic methods
  2. Elucidation and control of molecular dynamics in the condensed phase by ultrafast spectroscopy
  3. Observation and elucidation of molecular dynamics at interfaces by nonlinear spectroscopy
Coherent nuclear motion of the chromophor of a protein in reaction

Coherent nuclear motion of the chromophor of a protein in reaction

Selected Publications

  1. Kusaka, R., Nihonyanagi, S., and Tahara, T.: “The photochemical reaction of phenol becomes ultrafast at the air–water interface”, Nat. Chem. 13, 306 (2021).
  2. Inoue, K., Ahmed, M., Nihonyanagi, S. and Tahara, T.: “Reorientation-induced relaxation of free OH at the air/water interface revealed by ultrafast heterodyne-detected nonlinear spectroscopy” , Nat. Commun. 11, 5344 (2020).
  3. Ahmed, M., Inoue, K., Nihonyanagi, S., and Tahara, T.: “Hidden isolated OH at the charged hydrophobic interface revealed by two-dimensional heterodyne-detected VSFG spectroscopy” , Angew. Chem. Int. Ed. 59, 9498 (2020).
  4. Kuramochi, H., Takeuchi, S., Iwamura, M., Nozaki, K., and Tahara, T.: “Tracking photoinduced Au–Au bond formation through transient terahertz vibrations observed by femtosecond time-domain Raman spectroscopy” , J. Am. Chem. Soc. 141, 19296 (2019).
  5. Tahara, S., Kuramochi, H., Takeuchi, S., and Tahara, T.: “Protein dynamics preceding photoisomerization of the retinal chromophore in bacteriorhodopsin revealed by deep-UV femtosecond stimulated Raman spectroscopy” , J. Phys. Chem. Lett. 10, 5422 (2019).


Tahei TaharaTeam Leader
Kunihiko IshiiSenior Research Scientist
Satoshi NihonyanagiSenior Research Scientist
Korenobu MatsuzakiResearch Scientist
Ahmed MohammedResearch Scientist