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Multi-wavelength anomalous diffraction (sometimes Multi-wavelength anomalous dispersion; abbreviated MAD) is a technique used in X-ray crystallography that facilitates the determination of the three-dimensional structure of biological macromolecules (e.g. DNA, drug receptors) via solution of the phase problem.
Anomalous X-ray scattering (AXRS or XRAS) is a non-destructive determination technique within X-ray diffraction that makes use of the anomalous dispersion that occurs when a wavelength is selected that is in the vicinity of an absorption edge of one of the constituent elements of the sample. It is used in materials research to study nanometer ...
Schlieren imaging is a method to visualize density variations in transparent media. [1]Schlieren imaging of a focusing ultrasonic transducer Schlieren image sequence of a bullet traveling in free-flight, demonstrating the air pressure dynamics surrounding the bullet
For example, multi-wavelength anomalous dispersion phasing requires that the scattering be recorded at least three (and usually four, for redundancy) wavelengths of the incoming X-ray radiation. A single crystal may degrade too much during the collection of one data set, owing to radiation damage; in such cases, data sets on multiple crystals ...
XPS requires high vacuum (residual gas pressure p ~ 10 −6 Pa) or ultra-high vacuum (p < 10 −7 Pa) conditions, although a current area of development is ambient-pressure XPS, in which samples are analyzed at pressures of a few tens of millibar. When laboratory X-ray sources are used, XPS easily detects all elements except hydrogen and helium.
The RB arriving at detector 2 will have undergone a phase shift of (0.5 × wavelength + 2k) due to one front-surface reflection and two transmissions. The SB arriving at detector 2 will have undergone a (1 × wavelength + 2k) phase shift due to two front-surface reflections, one rear-surface reflection. Therefore, when there is no sample, only ...
The emission wavelength of the tunable diode laser, viz. VCSEL, DFB, etc., is tuned over the characteristic absorption lines of a species in the gas in the path of the laser beam. This causes a reduction of the measured signal intensity due to absorption, which can be detected by a photodiode , and then used to determine the gas concentration ...
It is optimised for very low-energy studies and long-wavelength diffraction. Pearl is a neutron diffractometer dedicated to high-pressure powder diffraction. Polaris is a neutron diffractometer optimised for the rapid characterisation of structures, the study of small amounts of materials, the collection of data sets in rapid time, and the ...