Incomplete measurements from CCDs in this technique can lead to a loss of information called the “phase problem.” For 10 points each:
[10e] Name this technique that uses low-wavelength light to probe lattice structures. Rosalind Franklin used this technique to determine the structure of DNA.
ANSWER: X-ray crystallography [or X-ray diffraction or XRD]
[10m] X-ray crystallography is limited in scale by the diffraction limit for this quantity usually measured in angstroms. A coefficient of 1.22 appears in the Rayleigh criterion for this quantity.
ANSWER: resolution [accept angular resolution; accept resolving power; prompt on angle]
[10h] Molecular modelling using X-ray crystallography uses this quantity defined by summing differences in structure factors over all reflections. A “free” form of this quantity is usually one tenth the resolution.
ANSWER: R-factor [or R-value; accept R-free; accept discrepancy index]
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