The experimental data were recorded by Kostyantyn Nasyedkin in the Quantum Condensed Phases Research Team, RIKEN CEMS, Japan, headed by Kimitoshi Kono and in collaboration with Aneta Stefanovska's group. Some of the data were used in the study on "Visualization of oscillatory electron dynamics on the surface of liquid helium", available at https://doi.org/10.1103/physrevb.107.104501. The experimental details are provided in the paper.