BL14-1

Beam line 14-1 employs a vertically collimating Rh-coated Si mirror, and a double-crystal Si(111) monochromator with a 0.013% energy bandpass producing ~2x1011 p/s at 10 KeV and providing an energy range that extends from 6 to 13 KeV. A vertically and horizontally focusing toroid mirror produces a beam focus of 50 x 80 um2. 

BL14-1 is equipped with a Pilatus 16M pixel array detector with a readout speed of up to 20 Hz which enables rapid high-redundancy diffraction experiments.  Automated energy changes support experimental phasing and excitation scans for rapid metal identification. 

Features and Techniques

Remote Access - Users control and carry out their experiments and run processing software in real time from anywhere in the world. This is accomplished with a simple free app that runs on the user's remote computer which connects to a server running at SSRL.
Automated Screening - Samples are systematically mounted from a frozen cassette or an ambient temperature container using a robot and subsequently aligned, exposed, indexed, and assigned a score for overall diffraction quality.

X-ray Rastering - Low-dose X-rays are used to accurately locate visually obscured crystals in loops and other mounts, or to identify areas of a crystal that have improved diffraction. 

MAD/SAD Phasing - Multi- and single wavelength anomalous diffraction (MAD and SAD, respectively) is used to solve the phase problem in structure determination.  Accurate heavy atom absorption edge spectra provide the most useful energies (f' and f") for MAD data collection.  High-speed ultra-redundant data collection can be used to obtain significant signal from weak anomalous scattering atoms such as sulfur.

Metal Identification – Excitation scans are useful to quickly determine the heavy element content in crystals.  The excitation scan measures the fluorescence counts from any element present in the sample with an absorption edge below the excitation energy. Excitation scans take less time than the MAD scans and thus are a faster way to determine the presence of a heavy atom derivative/ligand in the sample.
 

For more information on the features of BL14-1, see the Macromolecular Crystallography Website: https://smb.slac.stanford.edu