Figure 1

Temporal sequence of photoemission spectra ($12\mathrm{J}/{\mathrm{c}\mathrm{m}}^2$) at specified pump-probe delays (line with markers). Positive delay: x rays probe before the laser pump. A reference spectrum at $+240\mathrm{p}\mathrm{s}$ is also shown (no markers). Inset: Electron counts (97–99 eV, vicinity of shift) as a function of pump-probe delay. This curve ($80\pm 10\mathrm{p}\mathrm{s}$ FWHM), a convolution between the 80 ps x-ray pulse and the transient duration, indicates a photoemission transient $<50\mathrm{p}\mathrm{s}$.Reuse & Permissions

Figure 2

X-ray spectra ($12\mathrm{J}/{\mathrm{c}\mathrm{m}}^2$) for delays of $-160\mathrm{p}\mathrm{s}$ (circles, 1.7 eV FWHM peak width), 240 ps (crosses, 1.7 eV width), and 0 ps (bow ties, 2.7 eV width). The broadened peak is decomposed into two Gaussians of width 1.7 eV: a “perturbed” peak (at 98.7 eV with amplitude 115) and an “unperturbed” peak (100 eV with amplitude 115). The sum of these two Gaussians is also shown. Left inset : X-ray spectra ($4\mathrm{J}/{\mathrm{c}\mathrm{m}}^2$) for delays of 240 ps (crosses, 1.7 eV width), and 0 ps (bow ties, 2.3 eV width). The broadened peak is decomposed into two Gaussians (100.1 eV with amplitude 133, 99 eV with amplitude 60). The sum of these two Gaussians is also shown. Right inset: Both vertical axes indicate detected number of laser electrons per pulse. The time-integrated spectrum ($0–1\mu \mathrm{s}\mathrm{e}\mathrm{c}$; top and right axes) is shown as is the time history of electron emission (energy integrated; bottom and left axes). The initial (0–10 ns) measured yield of $\sim 0.1e^{-}$/shot indicates space charge contributions to this figure and Fig. 1 are $<0.1\mathrm{e}\mathrm{V}$ (see text).Reuse & Permissions