Fig. 2: Timing electron delocalization in Ar@C60.
From: Timing the escape of a photoexcited electron from a molecular cage
a Ar 2p3/2 → 4s partial electron yield X-ray absorption spectrum (filled circles) with Lorentzian fit (red line). The photon energy axis runs vertically and is the same as that for the resonant Auger-Meitner map shown in (b). The intensity axis (arbitrary units) runs horizontally. b Resonant Auger-Meitner map showing intensity of decay spectra as a function of photon energy. (Intensity is shown as a false colour map. While the units of this false colour scale are arbitrary, the values recorded by the CCD detector are directly proportional to the Auger-Meitner electron count rate. The CCD values span a range of ~29,000 to ~69,000 arbitrary units, i.e. the "29K" and "69K" limits shown on the colour bar alongside the map). The X-ray absorption spectrum shown in (a) both shares its photon energy axis with the resonant Auger-Meitner map and is also the line-by-line integral of the map. (A total electron yield spectrum is included in the Supplementary Information (Supp. Fig. 2)). Normal Auger-Meitner transitions are at fixed kinetic energy and therefore disperse diagonally with photon energy (red dashed lines), whereas the spectator peaks are at fixed binding energy (blue dashed lines). For clarity, the dispersion (or lack thereof) of all peaks is not shown. c Auger-Meitner electron spectra spanning ± 400 meV either side of the resonance condition in 100 meV increments. The on-resonance spectrum is plotted in black; the dashed blue line highlights the Ar 3s peak position. The Ar 3s peak intensity does not resonate and is constant to within 5%, highlighting the negligible contribution of participator transitions. (Note that the map in (b) and the set of spectra in (c) were acquired from different, but similarly prepared, Ar@C60 samples.) d On-resonance decay spectrum showing decomposition into the various normal Auger-Meitner and spectator components. Following Karis et al.64, we associate the shake-up features at ~ 32 eV and ~ 34 eV binding energy with spectator intensity of 3p45s1 character. See Supp. Note 3 for more details on the fitting process. The map in (b) shares its binding energy axis with the on-resonance spectrum. Source data are provided as Source Data files.
