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![[Figure 1]](ok5113fig1mag.jpg)
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Figure 1
Working principle of a ToF photoelectron microscope, demonstrated by ray-tracing calculations for a typical microscope geometry. (a, b) ToF-PEEM mode, illustrated by ray bundles around the fundamental rays uα, starting on the axis at an angle α, and uπ, starting parallel to the optical axis, as seen in the close-up view (a); the angles are greatly exaggerated. Lenses 1, 2 and 3 are multi-element groups, as schematically sketched; stigmators and deflectors are omitted. RP1, RP2 and RP3 (red dotted lines) are the reciprocal image planes; GP1, GP2 and GP3 (green dashed lines) are the Gaussian (real space) image planes; and DLD is the delay-line detector. (c, d) Same as (a, b), but for the momentum-microscopy mode. The first k image appears in the plane RP1 (backfocal plane of the front lens), marked in (c). In (b) and (d), the ToF drift sections are radially compressed by factors of 8 and 14, respectively. (e) kx–ky and (f) τ vs k∥ sections of a measured momentum pattern with three overlapping signals due to the temporal-aliasing effect. The largest pattern (1) corresponds to the electrons of interest with ToF τ. Patterns 2 and 3 result from slower and faster electrons with ToFs of τ + T and τ − T, respectively, where T is the period of the photon pulses. A series of fast core-level photoelectrons is visible as horizontal stripes in signal 3. (g) Intensity vs time schemes for photons and electrons (see main text for details). (Ray tracing using SIMION 8.0; Dahl et al., 2007  .) |
![[Figure 1]](ok5113fig1.jpg)
 | JOURNAL OF SYNCHROTRON RADIATION |
ISSN: 1600-5775
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