CiPo - Beamline

Normal Incidence Monochromator (NIM)

The beamline NIM monochromator equipped with two different holographic gratings, covers the 5 - 35 eV energy range by means of two different gratings, as follows:

  • Gold coated grating (2400 l/mm) from 10 to 35 eV

  • Aluminum coated grating (1200 l/mm) from 5 to 15 eV

The photon energy resolution at relevant energies of fundamental absorption line of He (21.2 eV) and Neon (16.7 eV) gases shows a FWHM of  about 4meV at He line and 2meV at Ne absorption structure with 20 um slit apertures. The FWHM is influenced by the photon bandpass and the contribution from the gas, which is made of the natural linewidth plus the experimental parameters such as gas pressure, effective light-path etc.. A reasonable value for the gas contribution to the FWHM could be considered of the order of 2 meV for the He line and of about 1 meV in the case of  Ne. Using these consideration, the available resolving power is of about 6000 at 21.2 eV and 10000 at 16.7 eV.

Last Updated on Wednesday, 13 February 2013 16:18