Institute of Crystallography - CNR


The beamline project dates back to 1990, as a joint project between the Department of Chemistry of the University of
Rome “La Sapienza”, Elettra Sincrotrone Trieste S.c.p.A, and the Institute of Structural Chemistry of the CNR (which in
2002 merged in the actual Institute of Crystallography)
The current beamline status has been planned in2005, to provide a brighter beam for monochromatic as well as
SAD/MAD experiments and high throughput in protein crystallography.

The layout of the beamline (Figure 1) consists of a pre-focusing cylindrical mirror that delivers to the nitrogen-cooled
monochromator an almost-parallel beam, which allows obtaining a monochromatic radiation with a ΔE/E of about 10 –
4 , necessary to operate in anomalous scattering conditions. The monochromatic beam is finally focused on the sample
by a toroidal (bendable) Pt-coated silicon mirror.
Figure 2

In the experimental station, (Figure 2) sample alignment is provided by a Huber k-geometry three-axis goniometer that allows the accurate orientation of the sample. Single-crystal Macromolecular crystallography just requires a single axis; nevertheless, different crystal orientations may be useful for specific applications. Moreover, the degrees of freedom proper of the k-goniometer are exploited in the automatic crystal mounting system. The reduced hindrance of the k-geometry makes also space for ancillary equipment required for sample monitoring or sample conditioning

While the k-goniometer allows a high flexibility in sample orientation, a bidimensional fast detector Pilatus 2M from Dectris collects the diffracted pattern. The detector is fast (read-out time:  5 ms) with a wide detecting area (253 x 2 288 mm 2 , dead area of 7%), no electronic noise and high dynamic range (20 bits, dynamic range > 10 6 ). The characteristics of Pilatus 2M are optimal for macromolecular and more in general single crystal diffraction
measurements. Other possible kind of experiments include High Pressure Powder Diffraction, Wide Angle X-ray Scattering from weakly diffracting materials, Grazing-Incidence Wide Angle X-ray Diffraction experiments from thin films and 2D-ordered materials.
Automatic sample mounting of frozen crystal through a Sample Changer that can  accommodate up to fifty frozen crystals mounted on sample holders complying with SPINE standards, can be performed at liquid nitrogen temperature. A robotic arm collects the sample from the storage and mounts it on the goniometer head, where the sample is kept under a 100 K nitrogen stream from an open cycle cryostat (Oxford Cryosystems 700).