Varying Energy
Energy modification
BM29 energy range is between 7 and 15 keV. The energy usually set is 12.5 keV which seems to "work better" for proteins being a result of compromise between absorption and scattering.
The energy of 12.5 keV is used with 1.8 mm diameter capillary. The ratio absorption/scattering being the best for an "average" protein in solution.
The energy can be easily set/modify in BsxCuBE gui by entering a desired number in energy tab. There is no particular issues for energies between 10 and 15 keV. For smaller energies, please consider that
- bending magnet flux drops very quickly (particularly below 8 keV), at 7.5keV you will have less than 100 times photons than at 12.5keV: increase ecquisition time;
- radiation damage can be worst than at higher energies;
- 1mm diameter capillary will be more adapted for absorption/scattering ratio: change it (how to change a pod is described in local contact info);
- some 'crazy' pixels, strange feature regions (grains of beamstop?) can appear on 2D images and consequently on 1D curves: sometimes is enough to slightly move the beamstop (by 0.1mm no more) or re-modify energy (by 0.1keV) and they disapear. If not, you can mask them, i.e. produce your own mask (see local contact info on Pilatus).