Finnish beamline at MAX-laboratory: Progress in the photon energy resolution

The photon energy resolution of the modified SX-700 plane gratingmonochromator at the Finnish beamline (BL51) at MAX-laboratory in Lund, Sweden, has improved considerably after proper alignment of the monochromator. Resolving powers of about 10 000 at h??90 eV and 5000 at h??400 eV have been achieved at the first diffraction order, as inferred from total ion yield measurements at the Kr 3d 5/2->5p and N2 N1s->?* resonances. The total linewidth of <=121 meV recorded for the Ar 2p 3/2->4s excitation suggests that the lifetime broadening could be smaller than 116 meV obtained from electron energy-loss spectroscopy.