Hole Decoherence of $\mathit{d}$ Bands in Copper

$d$-band hole decoherence times in copper are measured with energy and momentum resolution for the Cs/Cu(100) surface at 33–300 K by the interferometric time-resolved two-photon photoemission technique. At the top of the $d$ bands ( $X_5$ point) at 33 K the measured hole decoherence time of $T_2=34.5\mathrm{}\pm 1.5\mathrm{fs}$ has contributions from the population decay due to Auger recombination ( ${\tau }_{\mathrm{hh}}=24\mathrm{}\pm 3\mathrm{fs}$), and momentum scattering due to the hole-phonon interaction with a mass enhancement factor $\lambda =0.20\mathrm{}\pm 0.01$. Rapid decrease of $T_2$ with binding energy below the $X_5$ point suggests a larger cross section for $3d-3d$, as compared to $3d-4sp$ band scattering.