Changing the wavelength

Changing the energy in MxCube                    Changing the energy from the PX spec session

Changing the energy with MxCube

The energy range at BM16 is from 6.5 to 17 keV i.e. 1.9 to 0.7 Å. The first thing to do when changing wavelengths is to check the current energy. In MxCube the current energy/wavelength is given in the Energy box in the top left corner of MxCube.

The easiest way to change the energy/wavelength is by setting the new value you would like to go to in this box. Then press return or click on the pencil icon.

If you click on the units to the right of the energy box you can change the value either in KeV or in Angstroms, depending on whether you prefer to work in energies or wavelenthgs. When you reset the energy the wavelength will be changed automatically and various beamline alignment operations will be carried out to optimise the intensity at the new wavelength.

If you want to change the energy to do an Edge scan follow the procedure outlined here.

Note: please be patient when changing the energy as the alignment operations can take anything from 30 seconds to a few minutes, depending on the size of the energy jump you have made.

Changing the energy from the SPEC session

If you need to change the energy manually find the PX spec session which is usually iconised on the menu bar of BM16mach. Then type:

The PX session will return the energy and wavelength:

E=12.6581 keV, 0.979482 Angstroms

Small energy changes>

For small energy changes (i.e. smaller or equal to 0.5 keV) you do not need to realign the beam after you change energy. Just find the PX window and type moveE followed by the energy you want in units of keV.

PX> moveE (energy in keV!)

Large energy changes>

To change the energy by more than 0.5 keV, in the PX window type:

PX> newE (energy in keV!)>

On executing this command, the monochromator will be moved to the new wavelength and the diffractometer will be automatically re-aligned.>

<e.g. if you want to go to the Se edge type:>

PX> newE 12.658