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Figure 11
(a) Horizontal focal spot size at the sample position. For m = 1 and Δhν = 2.0% (green solid line) the spot size is below 32 µm for hν > 150 eV. For hν = 540 eV the spot size amounts to 15 µm. In this case 19000 lines of the grating are irradiated by light. The focal size decreases for a lower bandwidth of Δhν = 0.5% (green dashed line). At hν = 150 eV the horizontal spot size is 21 µm where 30000 lines of the grating are illuminated. For m = 2 the achievable spot size increases significantly. For Δhν = 2.0% it ranges between 32 µm and 18 µm. (b) At hν = 150 eV the induced group delay of the monochromator set-up is GD2.0% = 160 fs and GD0.5% = 45 fs. With increasing photon energy it decreases significantly. In the order m = 2 the group delay has an increased influence on the pulse duration, ranging from GD2.0% = 81 fs at hν = 500 eV to GD2.0% = 36 fs at hν = 800 eV. At hν = 700 eV the group delay amounts to GD2.0% = 45 fs. |