XRC Fees
X-ray crystallography (XRC) rates are dependent on the service requested. A list of rates and details for each service are outlined below.
Single Crystal X-Ray Diffraction
| Service | Caltech Rate | External Non-profit Rate |
|---|---|---|
| Unit Cell Determination | no charge | no charge |
| Partial Data Collection | $150 per sample | $250 per sample |
| Full Data Collection | $275 per sample | $450 per sample |
| Structure Refinement | $275 per sample | $450 per sample |
| Face Indexing | $60 per hour | $80 per hour |
| Powder Diffraction | $60 per hour | $80 per hour |
Services
Unit Cell Determination
A typical unit cell determination will allow for comparison of the current crystal to previous crystals but will not determine the contents of the unit cell. A unit cell determination is considered to be any collection with one run of less than 180 frames for molybdenum and 180 frames for copper, i.e. fast scan.
Full Data collection
In general, a data collection will obtain a complete data set and generally lead to a publishable crystal structure, dependent on the crystal and data quality. A data collection is any project with more than 250 frames for molybdenum or 400 frames for copper. This does not include structure refinement, see below.
Partial Collection
A partial collection / quick structure / connectivity / identification should be enough to get an idea of the structure of the molecule(s) in the crystal (i.e. where the atoms are and how they are bonded to each other) but the resulting structure will not be publishable. Any project that has between 180 and 250 frames (molybdenum) or between 180 and 400 frames (copper) will be considered a partial collection.
Structure Refinement
Structure refinement involves structure solution and refinement by facility personnel. All files necessary for publication will be prepared and sent to the submitter. Generally, this does not include images, which are the responsibility of the authors of the manuscript. Programs for generating images can be found in Aditional Resources.
Structure Determination
Structure determination involves facility personnel collecting and refining the structure. We will select an appropriate crystal, collect the diffraction data, solve, refine, and generate all files for publication. In short we will do everything.
Definitions
Absolute and Relative Configuration
For any molecules that are chiral, the absolute or relative configuration can be determined.
The relative configuration between different stereocenters can be determined for chiral molecules that are racemic mixtures or crystallize as racemic mixtures.
The absolute configuration of an enantiopure chiral molecule can also be determined. Determining the absolute configuration can be difficult and the following will help.
- Large, high quality crystals
- Atoms heavier than fluorine. This includes any solvent in the crystal.
Other Experiments
Other experiments such as powder diffraction or face indexing done on the single crystal diffractometers are are generally shorter than a typical single crystal experiment and are charged on an hourly basis.
Recollection
On occasion, problems can arise in data collection or structure refinement i.e. poor quality, extensive twinning, large amounts of disorder. In these cases it may be beneficial to grow better quality crystals. If the original data was collected in a reasonable manner and XRCF staff are consulted in the refinement, the collection fee may be waived for the recollection of better data. This is not common.
Any exceptions to the fee structure outlined above must be approved by the director and explained on the XRC Sample Submission Form for the sample. Any project without a XRC Sample Submission Form will be charged for a complete structure determination.
Crystals that are too small for the in-house diffractometers can be collected at the Standford Synchrotron Radiation Lightsource (SSRL). They will also be charged $275 for data collection per sample, if the sample diffracts well enough to process the data. The Molecular Observatory (Molobs) will also charge a small fee. Users who manage the samples themselves (mounting, loading and collecting) will only be charged the Molobs rate. Users will be contacted when the files have been completely processed and can either retrieve their sample directly from SLAC servers or refine their structure on the XRCF server. The normal $275 for structure refinement will apply for these samples if facility personnel determine the structure.