typo correction, you'll want the long axis parallel to the rotation
axis, not to the beam.
Mark
Quoting Frank von Delft:
You probably have to tilt your crystal, so that the long axis is
parallel to the beam. We do this routinely: cut a plastic pipette
tip to have a sharp point, then push the loop where it attaches to
the pin, to bend the crystal itself.
You have to identify from your diffraction whether the long axis is
pointing through the face or the edge of the loop. As it's P6,
chances are it's through the face, because long-axis P6 tends to
make flat hexagons which lie flush with the face. So you have to
bend so the face of the loop upwards.
You'll have to practice this first, though, so put up an empty loop.
Top tips:
* Don't breathe! You'll blow the cryostream away.
* Bend the loop towards (rather than away from) the rim edge of
the pin to which it's glued.
* Don't breathe!
* Practise practise practise.
Another thing: most in-house sources allow you to reduce divergence
of the beam. You lose intensity, but no matter, just expose longer.
That also improves overlap.
Cheers
phx
On 07/03/2012 04:56, Dipankar Manna wrote:
Dear Crystallographers,
I am working on a protein having SG P6, the cell parameters are a=
79, b= 79, c= 325. The crystals are forming in big size and with
very good shape. It also diffracting very well in Home source
facility both in terms of resolution and intensity. But the only
problem is the number of overlaps. Its showing much more than the
good spots. As a result the completeness is showing maximum up to
65% even after collecting 180 degrees. I am unable to get a
complete data. I tried with reducing the oscillation angel to 0.3
degree/0.5 degree but it did not improve that much. Please give me
some suggestions.
Regards,
Dipankar
/Dipankar Manna/
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