FAQ
Below is a list of the most frequently asked questions:
General
Users should contact the director for any questions.
X-Ray Crystallography (XRC)
X-Ray Powder Diffraction (XRPD)
X-Ray Crystallography
A XRC sample submission form is available as an editable PDF. Fill out as much of the form as possible, print it, draw a cartoon of your proposed structure in the space provided and either print and bring the form with your sample or upload it. Samples without a complete form will not be collected.
Unless you have been trained on the instrument and cleared to use it the XRCF staff will collect the data. Arrangements will be made to handle your sample in the most appropriate manner.
Yes.
We encourage users to collect their own data.
- Take the EHS X-ray Diffraction safety training
- XRCF staff will then train users in the use of the diffraction equipment.
Many groups refine their own structures after the data has been collected. There is no formal training for structure refinement but we recommend taking Ch122, Structure Determination by X-Ray Crystallography. XRCF staff are always available to help if problems arise.
For all structures determined by XRCF staff, the files necessary for publication will be sent to the submitter upon completion. Users who determine their own structures are responsible for processing and retrieving their own data as well as uploading the final structure to the XRCF server.
The data can be obtained from the server either by mounting a network drive in Windows or by direct download using a FTP client. For details and access to the server contact the director.
Generally samples are run on a first come first served basis, although no group will be permitted to use an instrument twice in a row if there are other groups in the queue. The wait time for data collection is dependent on the number of samples above yours in the queue and is typically less than a week.
Once the crystal is on the instrument, the length of the data collection is dependent on the crystal size and quality, but is typically less than 24 hours. Structure refinement is dependent on the individual crystal but will normally be completed within a week.
Structures are not automatically submitted to the Cambridge Crystallographic Data Centre (CCDC). The structure should be submitted to the CCDC before publication in order to obtain a deposition number. Structures can be submitted through the CCDC website.
X-Ray Powder Diffraction
A XRPD sample submission form is available as an editable PDF. Fill out as much of the form as possible, print it, draw a cartoon of your proposed structure in the space provided and either print and bring the form with your sample or upload it. Samples without a complete form will not be collected.
Unless you have been trained on the instrument and cleared to use it, the XRCF staff will collect the data. Arrangements will be made to handle your sample in the most appropriate manner.
Yes. Details here.
We encourage users to collect their own data.
- Take the EHS X-ray Diffraction safety training
- After the safety course, submit a completed New User form and
- schedule a 60-90 min instrument training session during which we will familiarize you with the collection of X-ray powder diffraction data.
- The focus of this training is on the operation of the instrument. This training is not meant to teach students about the principles of X-ray powder diffraction or data analysis. Those unfamiliar with data analysis procedures but in need of performing such analysis are encouraged to enroll in MS 142.
- When collecting data, all data should be collected in an users PI's folder. Any data not located in a PI's folder will be deleted at the end of the month.
The data is automatically transferred to the XRCF data server. The data can be obtained from the server either by mounting a network drive in Windows or by direct download using a FTP client. For details and access to the server contact the director.
The powder diffractometers can be reserved at the XRPD reservation site using their Caltech access information and reserve time on either of the powder diffractometers in 15 min increments.
The collection time will be dependent on the quality of data required, quality of the sample, and specific experiment run but 30 -60 min should be sufficient for a standard collection.