Coherent phonon coupling to individual Bloch states in photoexcited bismuth

Phys Rev Lett. 2012 Jun 22;108(25):256808. doi: 10.1103/PhysRevLett.108.256808. Epub 2012 Jun 20.


We investigate the temporal evolution of the electronic states at the bismuth (111) surface by means of time- and angle-resolved photoelectron spectroscopy. The binding energy of bulklike bands oscillates with the frequency of the A(1g) phonon mode, whereas surface states are insensitive to the coherent displacement of the lattice. A strong dependence of the oscillation amplitude on the electronic wave vector is correctly reproduced by ab initio calculations of electron-phonon coupling. Besides these oscillations, all the electronic states also display a photoinduced shift towards higher binding energy whose dynamics follows the evolution of the electronic temperature.