X-Ray Laboratory

X-Ray Laboratory

The X-ray laboratory at Harvard University provides access to the state-of-the-art equipment and technologies, holds crystallography course and X-ray diffraction application training, and offers advice and technical assistance in crystal growth, data collection, and structure refinement. Our facility opens to all Harvard members, as well as external users.

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Small Molecule Single Crystal Diffraction

Our X-ray laboratory has one brand new Bruker D8 VENTURE and two APEX DUO single crystal diffractometers. The D8 VENTURE is equipped with new PHOTON-100 CMOS detector, high brilliance Mo/Cu IµS microfocus X-ray sources and Oxford Cryosystream 800 series low temperature device, while the APEX DUO is equipped with APEX II CCD detector, Mo (Triumph)/Cu (IµS microfocus) X-ray sources and Oxford Cryosystream 700 series low temperature device.

The laboratory provides routine small molecule (up to 500 non-hydrogen atoms) crystal structure determinations (80-400 K), including determinations of the absolute configuration of biologically active compounds, which often do not contain atoms with larger resonant scattering signals than that of oxygen. Transmission-mode (in capillaries) powder diffraction data (80-400 K) can also be collected.

Our X-ray laboratory is regularly awarded beam time from the Advanced Photon Source (APS) Argonne National Lab for micro-crystallography studies, high resolution charge density studies, and resonant diffraction studies. Thanks to the tunable, high-intensity X-ray beams at ChemMatCARS, our X-ray laboratory has been using advanced crystallography as an essential research tool:

  1. Routine service crystallography for micro-sized crystals (less than 10 micron in two dimensions) that cannot be measured elsewhere.
  2. Charge density work, including ultra-high resolution, ultra-low temperature data collection, multipole refinement, and charge density analysis combined with theoretical calculations.
  3. Photo-crystallography in exploring molecular meta-stable states. The determination of molecular motions in the crystal is based on difference maps and disorder model refinements.  
  4. Structural studies at different temperature:  from ~10 K (Helium temperature) to 400 K.
  5. Resonant diffraction studies/Diffraction anomalous fine structure.
  6. Target guest structural determination by using crystalline sponge method.

Please contact the laboratory director, Dr. Shao-Liang Zheng for details.

 

X-Ray Diffraction for Thin Film and Powder Samples

Our X-ray laboratory also has a Bruker D2 PHASER and a D8 DISCOVER with DAVINCI Design X-ray powder diffractometer.

Powder X-Ray Diffraction Equipment

The D2 PHASER is a novel desktop X-ray diffraction tool enabling fast data collection for phase identification and Rietveld refinement.

The D8 DISCOVER with DAVINCI Design is equipped with both a zero/one-dimensional LynxEye detector and a two-dimensional VÅNTEC-500 detector. It is capable of performing:

  1. Qualitative and quantitative phase analysis by using Bragg-Brentano focusing with LynxEye geometry.
  2. X-ray reflectivity and high-resolution X-ray diffraction analysis of thin films by using Göbel mirror/ACC2 with LynxEye geometry.
  3. Stress measurement, texture analysis and non-destructive phase identification on the sample with even only 0.5 mm diameter area by using 2D X-ray diffraction (XRD2) with VÅNTEC-500 geometry.

The extra MRI temperature stage provides a wide range sample environment, from -180 to 1,400 Celsius.

Please contact the laboratory director, Dr. Shao-Liang Zheng for more details.

 

Crystal Mounting

The lab has two Zeiss SteREO Discovery V8 microscopes for routine mounting of samples, both configured with transmitted light polarization optics and AxioCam ERc5s Color CCD with AxioVision software

Temperature and/or air sensitive crystals are handled using a variety of techniques, some of which are described in the paper of "Macromolecular cryocrystallography—methods for cooling and mounting protein crystals at cryogenic temperatures " (J. W. Pflugrath, in Methods, 2004, 33, 415-425). The user can supply properly mounted crystals or have the laboratory director mount the crystals.

Zeiss Microscope