k-space@40.8eV

Momentum Microscope
(NanoESCA with k-space optics):
FOV?

By applying the k-space optics we achieve a k-space FOV of at least 6.0 Å^-1. We demonstrated this by means of using HeII radiation (40.8eV) to excite photo electrons from a well prepared Ag(111) surface.

This k-space image was taken at E – E_F = 40.8 eV.
sample:Ag(111)
excitation: He II (hν=40.8 eV, HIS 14 HD)Exposure Time 1000 s.
The length of the short line used for calibration is 2.51 Å^-1. The longer line is applied for the line scan shown at the right hand figure.
Maximum visible k-space (long line): 6.0 Å^-1 (2*k||, max. width for E_kin = 36.6eV)

The theoretical limit with the standard PEEM lens optics is about 7.3 Å^-1. With the 24kV objective lens, as used with the HAXPEEM, this limit is extended to about 8.3 Å^-1.