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Journal Article

X-ray free electron laser studies of electron and phonon dynamics of graphene adsorbed on copper

We report optical pumping and x-ray absorption spectroscopy experiments at the Pohang Accelerator Laboratory free electron laser that probes 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 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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Author(s)
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
Andew 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
Journal Name
Phys. Rev. Materials
Publication Date
February, 2023
DOI
10.1103/PhysRevMaterials.7.024005