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The New X-Ray Guy. Peter Müller. Peter Mueller. 4. Göttingen. 3. Kasierslautern. 1. Frankenthal / Mannheim. 2. La Chapelle Aux Bois. The New X-Ray Guy. The New Cryostream. And now: Some Crystallography. Judging the Quality of a Crystal. Determining the Best Exposure Time.
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The New X-Ray Guy Peter Müller Peter Mueller 4. Göttingen 3. Kasierslautern 1. Frankenthal / Mannheim 2. La Chapelle Aux Bois
And now: Some Crystallography • Judging the Quality of a Crystal. • Determining the Best Exposure Time. • Data Collection Strategy.
Judging the Quality of the X-tal Initial Immages Take two immages 90° appart.
Analyze Rocking Judging the Quality of the X-tal The Rocking Curve Number of frames in both directions Size of the box halfwidth = mosaicity
File Display File Display Analyze Contrast File Display Analyze Contrast 10 second frame 20 second frame 30 second frame Determining the Exposure Time Compare two (or more) immages that differ only in exposure time. Does a longer exposure time add information to the immage?
Determining the Exposure Time 20 seconds is better than 10 seconds. 30 seconds not better than 20 sconds. Our exposure time is 20 seconds per frame. Always collect a new dark current at your exposure time or at least load an older (but not too old!) dark current taken at your exposure time. compare
Detector Dark Current Collect Dark Current Now you are ready for data collection What is the best strategy?
omega phi The Platform Geometry
hkl reciprocal lattice point hkl reflection Diffracted beam Detector s P s d Q C O Incident beam Crystal hkl lattice planes Reciprocal lattice Ewald sphere with radius r = 1/l phi- and omega-scans phi- and omega-scansare orthogonal Omega-scansat different phi-angles Phi-scansat different omega-angles ...try to combine them!
Edit Multi Run Collect Dark Current Three 200° omega-scans and two 360° phi-scans Two 200° omega-scans and one 360° phi-scan that‘s plenty for any situation. is enough for mmmand higher.
We have a new HOMEPAGE http://web.mit.edu/x-ray
Next Meeting Tuesday November 9,11:00 a.m. AMDUR room (here) Data Reduction with SAINT and SADABS