Figure 1

Schematic top-view section of the UHV chamber at the beamline ID32 (ESRF) in which NIXSW experiments were performed.Reuse & Permissions

Figure 2

(a) LEED image (with electron beam energy of 19 $\mathrm{e}\mathrm{V}$) of the PTCDA/Ag(110) brick-wall phase on which NIXSW experiments were performed. The corresponding superstructure matrix is $(23\mid -23)$. (b) Schematic view of the brick-wall unit cell, with $a=b=11.9$ $\AA$ and $\gamma =86.7^{\circ }$ (Ref. 17).Reuse & Permissions

Figure 3

C1$s$ PE spectrum $I^{\exp }$ (open circles) of submonolayer PTCDA/Ag(110) with two fitting components $I_{Zj1}$ (green line) and $I_{Zj2}$ (magenta line) and the envelope $I^{\mathrm{env}}=I_{Zj1}+I_{Zj2}$ (gray line). The black line below the spectrum indicates the residuals ($I^{\exp }-I^{\mathrm{env}}$). The orange (black) straight line marks the linear background with $m=10$ ($m=0$) (see text).Reuse & Permissions

Figure 4

Plot of the ${(Y_{\text{C}1s1},Y_{\text{C}1s2})}^{MC}$ distribution resulting from the fit of 400 Monte Carlo simulations of the spectrum in Fig. 3. The blue ellipse contains all points of the distribution that lie within the confidence region ($68.3\%$ of all points). The center of the ellipse is the center of mass (CM) of the distribution. The principal axes are indicated by dotted blue lines. Points within the confidence region are represented by red open circles; those outside are marked by black open circles. The confidence interval of the two fitting parameters $2\sigma \left(Y_{\text{C}1s1}\right)$ and $2\sigma \left(Y_{\text{C}1s2}\right)$ are marked by dashed lines. Note that the axes are normalized to the PE yields of the center of mass $(Y_{1\mathrm{CM}},Y_{2\mathrm{CM}})$.Reuse & Permissions

Figure 5

(a) Ag3$d$ PE spectrum. (b) AgMNN Auger spectrum. Both spectra are marked by red open circles and are measured at $h\nu =4280$ $\mathrm{e}\mathrm{V}$. The Shirley (a) and linear (b) backgrounds are marked by a black line. (c) ${\text{Ag}3d}_{5/2}+{\text{Ag}3d}_{3/2}$ PE yield ($P_c=0.02\pm 0.01$, $F_c=0.98\pm 0.01$). The PE yield is normalized such that at photon energies away from the Bragg condition it is equal to 1. (d) AgMNN Auger electron yield ($P_c=0.99\pm 0.01$, $F_c=0.83\pm 0.02$). Experimental electron yields curves (green circles) are displayed as a function of the photon energy with respect to the Bragg energy. The corresponding fitting curves are marked by black lines.Reuse & Permissions

Figure 6

(a) PTCDA molecule. (b) C1$s$ mL-PE spectrum (open circles) of a PTCDA/Ag(100) multilayer ($\approx 40$ ML), measured at the beamline ID32 (ESRF, Grenoble). (c) Sum of 26 C1$s$ HR-PE spectra (open circles) of submonolayer PTCDA/Ag(110), measured with a laboratory source. (d) C1$s$ HS-PE spectrum (open circles) of submonolayer PTCDA/Ag(110), measured at the beamline ID32 (ESRF, Grenoble). The acquisition settings of spectra (b)–(d) are reported in Sec. 2b1. Displayed are PE intensity (open circles); ${\mathrm{C}}^{\mathrm{env}}$ (thick red line); ${\mathrm{C}}_2^{\mathrm{m}}$, ${\mathrm{C}}_3^{\mathrm{m}}$, ${\mathrm{C}}_4^{\mathrm{m}}$ (dark gray lines); ${\mathrm{C}}_1^{\mathrm{m}}$, ${\mathrm{C}}_1^{\mathrm{s}}$, ${\mathrm{C}}_1^{\mathrm{m}}+\mathrm{s}$ (light gray lines); ${\mathrm{C}}_{2,3,4}^{\mathrm{s}}$ (cyan line); ${\mathrm{C}}_5^{\mathrm{s}}$ (magenta line); ${\mathrm{C}}_6^{\mathrm{s}}$ (orange line); background (straight black line); and residuals (black line below each spectrum).Reuse & Permissions

Figure 7

PE yield of ${\mathrm{C}}_2^{\mathrm{m}}+{\mathrm{C}}_3^{\mathrm{m}}+{\mathrm{C}}_4^{\mathrm{m}}$ [(a) dark gray circles, $P_c=0.79\pm 0.01$, $F_c=0.35\pm 0.02$], ${\mathrm{C}}_1^{\mathrm{m}+\mathrm{s}}$ [(b) light gray circles, $P_c=0.64\pm 0.04$, $F_c=0.45\pm 0.09$], and ${\mathrm{C}}_5^{\mathrm{s}}$ [(c) magenta circles, $P_c=0.77\pm 0.03$, $F_c=0.41\pm 0.09$] corresponding to one NIXSW data set, with the fitting curves marked in black. The PE yield is normalized such that at photon energies away from the Bragg condition it is equal to 1. (d) Argand diagram ($P_c$, $F_c$) of ${\mathrm{C}}_2^{\mathrm{m}}+{\mathrm{C}}_3^{\mathrm{m}}+{\mathrm{C}}_4^{\mathrm{m}}$, ${\mathrm{C}}_1^{\mathrm{m}+\mathrm{s}}$, and ${\mathrm{C}}_5^{\mathrm{s}}$ corresponding to the average over the two NIXSW data sets.Reuse & Permissions

Figure 8

(a) O1$s$ HS-PE spectrum (open circles) of submonolayer PTCDA/Ag(110) measured at the beamline ID32 (ESRF, Grenoble) with the acquisition settings reported in Sec. 2b1. Displayed are ${\mathrm{O}}^{\mathrm{env}}={\mathrm{O}}_{\mathrm{carb}}^{\mathrm{m}}+{\mathrm{O}}_{\mathrm{carb}}^{\mathrm{s}}+{\mathrm{O}}_{\mathrm{anhyd}}^{\mathrm{m}}+{\mathrm{O}}_{\mathrm{anhyd}}^{\mathrm{s}}$ (black line), ${\mathrm{O}}_{\mathrm{carb}}^{\mathrm{m}}$ and ${\mathrm{O}}_{\mathrm{carb}}^{\mathrm{s}}$ (red lines), ${\mathrm{O}}_{\mathrm{anhyd}}^{\mathrm{m}}$ and ${\mathrm{O}}_{\mathrm{anhyd}}^{\mathrm{s}}$ (blue lines), background (gray line), and residuals (black line below the spectrum). (b) ${\mathrm{O}}_{\mathrm{carb}}^{\mathrm{m}}+{\mathrm{O}}_{\mathrm{carb}}^{\mathrm{s}}$ PE yield (red circles). (c) ${\mathrm{O}}_{\mathrm{anhyd}}^{\mathrm{m}}+{\mathrm{O}}_{\mathrm{anhyd}}^{\mathrm{s}}$ PE yield (blue circles). The fitting curves of the PE yields are marked in black. The PE yield is normalized such that at photon energies away from the Bragg condition it is equal to 1. (d) Argand diagram ($P_c$, $F_c$) of ${\mathrm{O}}_{\mathrm{carb}}^{\mathrm{m}}+{\mathrm{O}}_{\mathrm{carb}}^{\mathrm{s}}$ (red circle), ${\mathrm{O}}_{\mathrm{anhyd}}^{\mathrm{m}}+{\mathrm{O}}_{\mathrm{anhyd}}^{\mathrm{s}}$ (blue circle), ${\mathrm{O}}^{\mathrm{env}}$ (black circle) corresponding to the average over three NIXSW data sets, plus the weighted sum of ${\mathrm{O}}_{\mathrm{carb}}$ and ${\mathrm{O}}_{\mathrm{anhyd}}$ ($P_c$, $F_c$) (green $+$; see text).Reuse & Permissions

Figure 9

(a) Side view (along the long molecular axis) of PTCDA/Ag(110). (b) Side view (along the short molecular axis) of PTCDA/Ag(110). (c) Top view of PTCDA/Ag(110). Solid circles indicate the atomic positions. In panel (b), solid lines indicate covalent radii (Ref. 54) ($r_{cov}^{\mathrm{C}}=0.73$ $\AA$, $r_{cov}^{\mathrm{O}}=0.66$ $\AA$, $r_{cov}^{\mathrm{Ag}}=1.45$ $\AA$) and dotted lines indicate van der Waals radii (Ref. 55) ($r_{vdW}^{\mathrm{C}}=1.75$ $\AA$, $r_{vdW}^{\mathrm{O}}=1.50$ $\AA$, $r_{vdW}^{\mathrm{Ag}}=1.72$ $\AA$).Reuse & Permissions