Ultrafast electron cooling in Ti3C2Tx MXene revealed by time-resolved photoemission spectroscopy

Ultrafast electron dynamics in a Ti3C2Tx MXene thin film (where Tx denotes surface terminations) were inves- tigated using time-resolved photoemission spectroscopy with temporal resolution of 110 fs. Near-infrared optical excitation at 800 nm induces a transient redistribution of electronic states in the vicinity of the Fermi level, which is directly probed using extreme-ultraviolet (26.5 eV) pulses. The measured signal reveals a rapid modification of the electronic distribution immediately after excitation, followed by relaxation on sub-0.5 ps timescales, as quantified by the evolution of the electronic temperature. These results provide direct insight into hot-electron lifetimes and open the study of relaxation pathways in MXene thin films, establishing a framework for further understanding and optimizing their performance.