X-ray Free Electron Laser Studies of Electron and Phonon Dynamics of Graphene Adsorbed on Copper

Hirohito Ogasawara; Han Wang; Jörgen Gladh; Alessandro Gallo; Ralph Page; Johannes Voss; Alan Luntz; Elias Diesen; Frank Abild-Pedersen; Anders Nilsson; Markus Soldemo; Marc Zajac; Andrew Attar; Michelle E. Chen; Sang Wan Cho; Abhishek Katoch; Ki-Jeong Kim; Kyung Hwan Kim; Minseok Kim; Soonnam Kwon; Sang Han Park; Henrique Ribeiro; Sami Sainio; Hsin-Yi Wang; Cheolhee Yang; Tony Heinz

arXiv · 2211.00736

X-ray Free Electron Laser Studies of Electron and Phonon Dynamics of Graphene Adsorbed on Copper

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Abstract

We report optical pumping and X-ray absorption spectroscopy experiments at the PAL free electron laser that directly probe the electron dynamics of a graphene monolayer adsorbed on copper in the femtosecond regime. By analyzing the results with ab-initio theory we infer that the excitation of graphene is dominated by indirect excitation from hot electron-hole pairs created in the copper by the optical laser pulse. However, once the excitation is created in graphene, its decay follows a similar path as in many previous studies of graphene adsorbed on semiconductors, i e. rapid excitation of SCOPS (Strongly Coupled Optical Phonons) and eventual thermalization. It is likely that the lifetime of the hot electron-hole pairs in copper governs the lifetime of the electronic excitation of the graphene.

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Hirohito Ogasawara, Han Wang, Jörgen Gladh, Alessandro Gallo, Ralph Page, Johannes Voss, Alan Luntz, Elias Diesen, Frank Abild-Pedersen, Anders Nilsson, Markus Soldemo, Marc Zajac, Andrew Attar, Michelle E. Chen, Sang Wan Cho, Abhishek Katoch, Ki-Jeong Kim, Kyung Hwan Kim, Minseok Kim, Soonnam Kwon, Sang Han Park, Henrique Ribeiro, Sami Sainio, Hsin-Yi Wang, Cheolhee Yang, Tony Heinz. 2022-11-01. X-ray Free Electron Laser Studies of Electron and Phonon Dynamics of Graphene Adsorbed on Copper. https://arxiv.org/abs/2211.00736

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