Installing a monochromator

This blog post shows the steps required to install a monochromator upgrade on a PHI 5600 XPS system.

The components of a monochromator upgrade include the monochromator housing, the crystal substrate and aligner, the mono X-ray source, and the X-ray source aligner.    If your X-ray source is a 32-095 then you will need to replace that with a 32-096 that can drive two x-ray sources (standard dual anode and mono source). An additional water line is included to complete the cooling circuit between the standard and mono X-ray sources.

Step by step procedure:

First, vent the vacuum chamber.

Use a new 4 5/8” copper gasket and install X-ray source X Y Z aligner to the monochromator housing.  It is much easier to install the X Y Z aligner onto the mono housing before the mono housing is mounted to the chamber.

Use a new 6” copper gasket and Install the monochromator housing to the chamber on the flange that is opposite of the hemispherical analyzer.  It is heavy and so you will need at least two people to mount the monochromator housing to the flange on the chamber. 

Once mounted tighten the nuts on the flange.  In my experience, going in a circular pattern is the best way to tighten flanges on UHV chambers.   The trick is to not over-tighten the nuts or bolts as you go around.  Start out with just a little bit of torque and gradually increase it as you go around.   One or two of the nuts on the back of the monochromator housing are exceedingly difficult to get to.  A ½” U-shaped or half-moon wrench makes getting to those nuts easier. 

Or you can simply cut a standard ½” wrench in half. 

Once the nuts are tight and there is no gap between the flanges it is sealed.

Install the mono crystal substrate into the top mono flange assembly:  Use gloves and very carefully remove the crystal substrate from its box and unwrap it, being careful not to touch the crystals.  There are 3 recesses in the crystal block that line up with flat spaces on the mono flange assembly. 

The crystal substrate is held in place with 3 clamps.  The clamps mount on a guide screw and then there are two spring loaded set screws that provide tension to hold the crystal substrate in place.  

Tighten the set screws to where they just start to tighten up, and then about 1/16” more.   Do not over-tighten the set screws.  They should be tight enough to hold the crystal substrate in place firmly, but not so tight that the springs inside the set screws are fully compressed.

Next, install a new rectangular Helicoflex type monochromator gasket into the top of the monochromator housing. It will sit into a recess and should be centered in the recess.

Put the mono housing shutter in the bakeout position.  The chamber will be baked out and so the shutter will need to be set prior to the bake out.  Also, you can see how the shutter works before the top mono flange is installed.

Install the top mono flange assembly onto the top of the mono housing.  This can be done by one person.  Make sure that the crystal substrate does not touch the sides of the mono housing as you lower the mono flange assembly.   There are two guide pins to hold the mono flange assembly in place.   The serial number on the mono flange assembly should line up with the serial number on the mono housing.

Install the bolts into the holes in the mono flange assembly and tighten them.   For this flange, use little torque as you tighten the flange in a circular (rectangular) pattern.  The bolts are coarse threads and you want to tighten the flange evenly. 

Once the bolts are tight and there is no gap between the two flanges then it should be sealed.

Use a new 6” copper gasket and mount the 10-610 mono X-ray source to the 6” flange on the X Y Z aligner and tighten the nuts until there is no gap between the flanges or until the nuts are very tight, which ever comes first. 

At this point the chamber can be pumped down and baked out.   Make sure that all the housing parts and O-ring seals are removed from the 10-610 mono source prior to bake out.

The pictures below show the components of the 10-610 X-ray source as they are reassembled after the bake out.

After the chamber has been baked out, refer to the 10-610 mono X-ray source and 10-420 monochromator manuals for outgas, operation, and alignment information.