Electron transfer in a virtual quantum state of LiBH4 induced by strong optical fields and mapped by femtosecond x-ray diffraction.
Transient polarizations connected with a spatial redistribution of electronic charge in a mixed quantum state are induced by optical fields of high amplitude. We determine for the first time the related transient electron density maps, applying femtosecond x-ray powder diffraction as a structure probe. The prototype ionic material LiBH4 driven nonresonantly by an intense sub-40 fs optical pulse displays a large-amplitude fully reversible electron transfer from the BH4(-) anion to the Li+ cation during excitation. Our results establish this mechanism as the source of the strong optical polarization which agrees quantitatively with theoretical estimates.
Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, 12489 Berlin, Germany.
J
J
Stingl
F
F
Zamponi
B
B
Freyer
M
M
Woerner
T
T
Elsaesser
A
A
Borgschulte