Figure 1

(Color online) Two-electron photoemission for a monolayer of ${\mathrm{C}}_{60}$ on Cu(111) measured at $h\nu =45$ at normal incidence. Top panel shows color coded distribution of double emission events as a function of the kinetic energies; lower panel shows energy sharing for $3\mathrm{eV}$ wide intervals centered at two-electron binding energies represented by different symbols.Reuse & Permissions

Figure 2

(Color online) Two-electron sharing distributions for the 10 ML film for light incidence under 35° to the surface normal. The two TOF detectors are under 75° and $-5°$ to the surface normal. The 2eBE windows for which the sharing distributions have been determined are 6–9 (diamonds), 9–12 (triangles down), 12–15 (triangles up), 15–18 (circles), and $18–21\mathrm{eV}$ (squares).Reuse & Permissions

Figure 3

Two-electron binding energy distribution from two-electron photoemission of ${\mathrm{C}}_{60}$ adsorbed on Cu(111), taken at $45\mathrm{eV}$ photon energy under normal light incidence, and electron collection at $\pm 40°$ to the surface. Upper panel, ${\mathrm{C}}_{60}$ monolayer; lower panel, thick layer.Reuse & Permissions

Figure 4

Fine structure in two-electron photoemission from ${\mathrm{C}}_{60}$ on Cu(111). (a) Two-electron photoemission of a ${\mathrm{C}}_{60}$ monolayer on Cu(111) (filled circles, same data as upper panel in Fig. 2). To reveal fine structure, a linear background was subtracted. (b) Open squares show the carbon $KVV$ Auger spectrum after subtraction of smooth background (from Ref. 3). Full line gives the self-convolution of the valence band density of states, shifted by $1.6\mathrm{eV}$ to higher two-electron binding energy. The fine structure in two- electron photoemission spectrum resembles that found in the Auger spectrum and the self-convoluted DOS. (c) Two-electron PE spectrum for a thick film of ${\mathrm{C}}_{60}$ on Cu(111). After subtraction of a smooth spline the spectra oscillate around zero; for spectra (b) and (c) arbitrary offsets of $-500$ and $-1250$ were introduced to avoid overlap.Reuse & Permissions