  Utilizing femtosecond optical pump-probe technique, we have studied transient
Fano-resonance in zinc. At high excitation levels the Fourier spectrum of the
coherent E$_{2g}$ phonon exhibits strongly asymmetric line shape, which is well
modeled by the Fano function. The Fano parameter (1/Q) was found to be strongly
excitation fluence dependent while depending weakly on the initial lattice
temperature. We attribute the origin of the Fano-resonance to the coupling of
coherent phonon to the electronic continuum, with their transition
probabilities strongly renormalized in the vicinity of the photoinduced
structural transition.
