Photoemission time delays from condensed matter (time-resolved ARPES)

Time-resolved ARPES experiments allow one to track the evolution of electronic excitations in surfaces as function of binding energy and electron momentum. First attosecond experiments on solid surfaces were based on attosecond streaking. We applied the RABBITT technique for the first time on solid surfaces in 2015 after we have gain a lot of experience with this techniques with atoms (link to Photoemission section) and found a strong energy-dependent variation of photoemission delays from the d-valence bands of Ag(111) and Au(111).

[389] R. Locher, L. Castiglioni, M. Lucchini, M. Greif, L. Gallmann, J. Osterwalder, M. Hengsberger, U. Keller
Download"Energy-dependent photoemission delays from noble metal surfaces by attosecond interferometry" (PDF, 1.6 MB)vertical_align_bottom
Optica, vol. 2, No. 5, pp. 405-410, 2015

We made sure that the Fresnel Equations still work for copper surfaces within 50 attosecond accuracy.

[397] M. Lucchini, L. Castiglioni, L. Kasmi, P. Kliuiev, A. Ludwig, M. Greif, J. Osterwalder, M. Hengsberger, L. Gallmann, U. Keller
Download"Light-matter interaction at surfaces in the spatiotemporal limit of macroscopic models" (PDF, 877 KB)vertical_align_bottom
Phys. Rev. Lett., vol. 115, 137401, 2015

Most recently we repeated such measurements on copper and could define an upper limit of 320 ± 40 as for the travel time an electron needs to assume an effective mass. This demonstrates the validity of the effective mass concept down to atomic scale propagation.

L. Kasmi, M. Lucchini, L. Catiglioni, P. Kliuiev, J. Osterwalder, M. Hengsberger, L. Gallmann, P. Krüger, U. Keller
"Effective mass effect in attosecond electron transport"
submitted