Paper

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

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

2022

Overview

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.

• Publisher: Cornell University Library, arXiv.org
• Subject: Absorption spectroscopy / Copper / Excitation / Femtosecond pulses / Free electron lasers / Graphene / Holes (electron deficiencies) / Hot electrons / Optical pumping / Phonons / Thermalization (energy absorption) / X ray absorption