This recent discussion does tend towards the ideal scenario: of identifying ones
best-diffracting crystals... before embarking on the synchrotron trip.
The established Oxford Diffraction PX Scanner home laboratory instrument can
therefore be most useful. This enables the direct X-ray screening of individual
(putative) single crystal objects, in situ, in the (any SBS format)
crystallisation plate.
Yours sincerely,
Marcus Winter (Oxford Diffraction Ltd. - now Agilent Technologies)
-----Original Message-----
From: CCP4 bulletin board [mailto:ccp...@jiscmail.ac.uk] On Behalf Of Phil
Jeffrey
Sent: 28 September 2010 19:20
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] Lousy diffraction at home but fantastic at the
synchrotron?
Often this reflect crystal size - a small crystal in a big beam (or one
with a long path in air) on a home source would see the small
diffraction signal drop below the noise level quite quickly - often at
the low resolution intensity dip that sits very approximately around 6
Angstrom. On a synchrotron source with a tight low-divergence beam that
matches more closely the crystal dimensions that same crystal will
appear to do rather better.
Also one is more likely to expose the crystal longer (in terms of total
photon numbers) at a synchrotron, which itself begets better signal/noise.
Alternatively: everyone tries harder before synchrotron trips....
Phil Jeffrey
Princeton
On 9/28/10 1:27 PM, Francis E Reyes wrote:
> Hi all
>
> I'm interested in the scenario where crystals were screened at home and
> gave lousy (say < 8-10A) but when illuminated with synchrotron radiation
> gave reasonable diffraction ( > 3A) ? Why the discrepancy?
>
> Thanks
>
> F
