CCB's X-ray Laboratory provides access to state-of-the-art equipment and technologies, hosts a crystallography course and X-ray diffraction application training, and offers advice and technical assistance in crystal growth, data collection, and small-molecule crystal structure determination.
Small-Molecule Single Crystal Diffraction
And two APEX DUO single crystal diffractometers equipped with APEX II CCD detector, Mo (Triumph)/Cu (IµS microfocus) X-ray sources, and Oxford Cryosystream 700 series low temperature device.
Our facility 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.
And, we can collect transmission-mode (in capillaries) powder diffraction data (80-400 K).
Thanks to the beam time from Advanced Photon Source (APS) Argonne National Lab and TOPAZ Oak Ridge National Lab (ORNL), our X-ray laboratory has been using advanced crystallography as an essential research tool for:
- Routine service crystallography for micron-sized crystals (less than 10 micron in two dimensions) that cannot be measured elsewhere.
- Charge density work, including ultra-high resolution, ultra-low temperature data collection, multipole refinement, and charge density analysis combined with theoretical calculations.
- Photocrystallography in exploring molecular meta-stable states. The determination of molecular motions in the crystal is based on difference maps and disorder model refinements.
- Structural studies at different temperature: from ~10 K (Helium temperature) to 400 K.
- Resonant diffraction studies/Diffraction anomalous fine structure, used for the determination of the atoms that are close in the periodic table and/or difference valence states for the same element.
- Target guest structural determination by using crystalline sponge method, used for the determination of the structures of original compounds that are liquids or amorphous solids.
X-ray Diffraction for Thin Film and Powder Samples
Our facility also has a Bruker D2 PHASER, a novel desktop X-ray diffraction tool enabling fast data collection for phase identification and Rietveld refinement.
And a D8 DISCOVER with DAVINCI Design X-ray powder diffractometer equipped with a zero/one-dimensional LynxEye detector and a two-dimensional VÅNTEC-500 detector.
It is capable of performing:
- Qualitative and quantitative phase analysis by using Bragg-Brentano focusing with LynxEye geometry;
- High-resolution X-ray diffraction and X-ray reflectivity (HRXRD/XRR) analysis of thin-film samples by using Göbel mirror/ACC2 with LynxEye geometry;
- 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.
Our facility has two Zeiss SteREO Discovery V8 microscopes for routine mounting of samples, configured with transmitted light polarization optics or AxioCam ERc5s Color CCD with AxioVision software.
And, we handle temperature and/or air sensitive crystals with a variety of techniques, many of which are detailed in the paper, "Macromolecular cryocrystallography—methods for cooling and mounting protein crystals at cryogenic temperatures". You can either supply your own properly mounted crystals or have the laboratory director mount the crystals for you.
Small-Molecule Crystallography Service
Single crystal quality is perhaps the most important factor in determining the final precision for a given X-ray structural investigation. High precision structural results require high-quality crystals. In general, crystals for an X-ray study must be single and of the proper size and shape. The crystal can usually be analyzed in-house if they are at least 0.02 mm thick in two dimensions. If we cannot collect reasonable resolution data for micron-sized crystals, we can analyze them with synchrotron radiation data sets. We also provide the data processing and structure determination for the 3DED/MicroED data sets using dynamical diffraction theory.
Please submit a request form (available below or in the laboratory):
- Harvard Submission form for those at Harvard University
- General Submission Form for those outside Harvard University
- External User Intake Form, required by CCB Finance Team
Data collection and structure determinations are performed on a first-come, first-serve basis. If you are preparing a highly unstable material, please make arrangements ahead of time with the laboratory director. When a structure is considered final and complete, all necessary data (cif, tables, Ortep, etc.) will be sent to the user and his/her group advisor. The user is responsible for safekeeping his/her own released data
Become a DIY user
The X-ray facility strongly encourages user participation in structure determination and refinement and graphics interaction of molecular structure determinations. Users who wish to participate in single-crystal structure determination, powder sample measurement and thin films analysis (DIY users) may do so after:
- Submitting the Harvard ID Application Form, required by Department Director's Office, if you are the non-CCB users who haven't been assigned an ID yet. Once approval is complete, you can contact the Harvard ID office to request your Harvard ID card and then request your HarvardKey. Contact Hannah Kelley if you have further questions.
- Completing the online radiation safety training ("X-Ray Devices training") before using the diffractometers. Please contact Mathieu Lalonde, our Science Safety Officer, if you have any questions.
- Taking Chem 255: Practical Crystallography in Chemistry and Materials Science.
- Participating in our regularly held instrument orientation and application training sessions. Contact Laboratory Director Shao-Liang Zheng for details.
To reserve for powder diffraction, apply for a FAS RC account and inform the laboratory director, Shao-Liang Zheng, of the email address you used to sign up. Please contact email@example.com if you run into technical issues.
Our Laboratory follows Harvard's Academic Service Center Policy. The external users also need to submit the External User Intake Form, required by CCB Finance Team. Contact Liz Bean and CCB Finance Team if you have further questions regarding the billing.
Currently, we are approved to open our facility to DIY users as long as the users follow Harvard University On Campus Activity Guidance. Face masks are strongly encouraged in the X-ray Lab and required during the training. Contact the laboratory director, Shao-Liang Zheng, with questions.
Co-Authorship and Acknowledgements
The laboratory director can help complete X-ray components of experiments and review the manuscript.
The director should be considered for co-authorship if:
- The structural information that has been derived mainly from the diffraction data is an important part of the paper, and/or
- The structure determination is non-routine, such as photocrystallographic studies, and/or
- The final structure involved a substantial amount of time and technical expertise, such as problematic twinning or whole-molecule disorder structure refinement.
An acknowledgment is more appropriate if structure determination was used only to confirm information obtained by other means (NMR, MS, etc.) and no structural details will be given in the paper. For example, "We thank Dr. Shao-Liang Zheng for his help with the X-ray data collection and structure determination."
For X-ray diffraction data collected on D8 DISCOVER with DAVINCI Design, you need only write: Authors are grateful for the assistance of Dr. Shao-Liang Zheng with the X-ray analysis.
We welcome students from all levels—high school, undergraduate, graduate and post-graduate—to our X-ray laboratory. Visitors learn about X-ray science and instrumentation through hands-on activities. To schedule your visit, please contact the laboratory director, Shao-Liang Zheng.
Chemistry 255. Practical Crystallography in Chemistry and Materials Science
Due to great technical advances, crystal structure analysis plays an increasingly important role in the structure determination of complex solids. This course involves the basic principles of crystallography and covers advanced aspects of practical crystal structure refinement. Topics include: crystal symmetry, space groups, geometry of diffraction, structure factors, and structure refinement. Students gain a working knowledge of X-ray crystallographic techniques, including how to: grow quality crystals, collect data, reduce data, determine a small-molecule structure, visualize structure, utilize structural databases, publish crystallographic results. Course-related Video
- Connecting Key Concepts with Student Experience: Introducing Small-Molecule Crystallography to Chemistry Undergraduates Using a Flexible Laboratory Module
- Teaching with the Case Study Method to Promote Active Learning in a Small Molecule Crystallography Course for Chemistry Students
- Resolving Space-Group-Choice Dilemma in Small-Molecule Crystallography for Chemistry Students Using Case-Based Learning Modules
- Teaching Space-Group Diagrams to Chemistry Students through a Peer-Tutoring Approach
- Teaching Outside the Classroom: Field Trips in Crystallography Education for Chemistry Students
- From the Source: Student-Centred Guest Lecturing in a Chemical Crystallography Class