Small atomic displacements recorded in bismuth by the optical reflectivity of femtosecond laser-pulse excitations.
Subtle atomic motion in a Bi crystal excited by a 35 fs-laser pulse has been recovered from the transient reflectivity of an optical probe measured with an accuracy of 10(-5). Analysis shows that a novel effect reported here-an initial negative drop in reflectivity-relates to a delicate coherent displacement of atoms by the polarization force during the pulse. We also show that reflectivity oscillations with a frequency coinciding with that of cold Bi are related to optical phonons excited by the electron temperature gradient through electron-phonon coupling.
Boschetto
D
D
Laboratoire d'Optique Appliquée, ENSTA/Ecole Polytechnique, Palaiseau, France. davide.boschetto@ensta.fr
Gamaly
E G
EG
Rode
A V
AV
Luther-Davies
B
B
Glijer
D
D
Garl
T
T
Albert
O
O
Rousse
A
A
Etchepare
J
J