Department of Chemistry

X-ray Diffraction Laboratory


Services in XCL can be categorized into the followings:
Single-crystal X-ray Diffraction (SCXRD)

SCXRD is a non-destructive experimental technique which reveals unambiguous structural information such as unit cell dimensions, space group, atomic connectivity, bond lengths and angles, site occupancy and thus, the overall three-dimensional molecular structure in a single crystal.

Users can submit single-crystal samples to XCL for diffraction experiment. Data collection can be done at room temperature or low temperature (usually 100 K). Some crystal samples may require special treatments such as air-sensitive crystal, structure with disordered moieties, and absolute structure determination for chiral compounds. For more information on preparation of single crystal, please refer to the Resources - Crystallization page.

A checked CIF file and a structural report will be provided after the experiment.

Powder X-ray Diffraction (PXRD)

PXRD can be used for phase identification of a crystalline material and can provide information on unit cell dimensions and interplanar spacing. If a high-quality diffractogram is obtainable, crystal structure can be determined by performing indexing, space group determination, simulated annealing and Rietveld Refinement of the diffraction data.

Users can submit polycrystalline powder samples to the XCL for diffraction experiment. A common sample size is about 1 cm2 in diameter or 200 mg in weight. Data collection can be done at room temperature or high temperature (from 300 to 1000 K). Thorough discussion on the possibility for structural determination from powder diffraction data should be made before data collection because the process demands non-routine technique and substantial experimental time.

An ASCII file of the diffractogram will be provided after the experiment. Phase identification with Powder Diffraction File (PDF) database is available.

Grazing Incidence X-ray Diffraction (GIXRD)

GIXRD is a technique for studying the crystalline structure of a surface or a thin film on a substrate. Unlike conventional symmetrical theta-2 theta scan, a grazing angle of incidence X-ray beam is fixed near or below the critical angle for total reflection, the incident beam is evanescent and penetrates only the top 100 Å or less into the surface.1 to avoid the diffraction signal from the surface being masked by those from the substrate.

Thin film samples should be larger than 1 cm2 in diameter. The critical angle of the film should be provided along with the sample.

An ASCII file of the diffractogram will be provided after the experiment. Phase identification with Powder Diffraction File (PDF) database is available.

Note 1: Huang and W. Parrish, Adv. X-ray Anal., Vol. 35, pp. 137, 1992



For more information, please contact Dr. Kam-Hung Low: khlow@hku.hk