Testing of a `hard' X-ray interferometer for experimental investigations

A `hard' X-ray LLL interferometer is tested for experimental investigations. The interferometer has both a base and a `ceiling', which are rigidly connected through columns. As a result, the interferometer does not have uncontrollable preliminary moiré. The intensity distribution is uniform in the interfering beams. It is shown that the interferometer is very sensitive to minor mechanical stresses. As a result, the interferometer must be freely placed on the goniometer head. Constant-thickness fringes are obtained using a wedge with a vertically placed apex. The volumes available for specimen placement are limited due to the existence of the ceiling. These difficulties can be overcome. The hard interferometer can be used for object and deformation investigations.

The use of a mini-κ goniometer head in macromolecular crystallography diffraction experiments

Most macromolecular crystallography (MX) diffraction experiments at synchrotrons use a single-axis goniometer. This markedly contrasts with small-molecule crystallography, in which the majority of the diffraction data are collected using multi-axis goniometers. A novel miniaturized κ-goniometer head, the MK3, has been developed to allow macromolecular crystals to be aligned. It is available on the majority of the structural biology beamlines at the ESRF, as well as elsewhere. In addition, theStrategy for the Alignment of Crystals(STAC) software package has been developed to facilitate the use of the MK3 and other similar devices. Use of the MK3 andSTACis streamlined by their incorporation into online analysis tools such asEDNA. The current use ofSTACand MK3 on the MX beamlines at the ESRF is discussed. It is shown that the alignment of macromolecular crystals can result in improved diffraction data quality compared with data obtained from randomly aligned crystals.

Upgrade of automated sample exchanger SPACE

SPACE (SPring-8 precise automatic cryo-sample exchanger) is an automated sample exchanger for cryo-cooled protein crystals, developed at SPring-8. Since the start of its operation, SPACE has been continuously improved and upgraded to cope with the requirements of new beamlines and users. One important upgrade of SPACE provides support for conventional metal-base pins, which are attached to the goniometer head magnetically. Other hardware improvements include increasing the sample storage capacity. The upgraded version of SPACE, as reported here, is continuously operated and is an essential component of beamline operation at SPring-8.

Automatic loop centring with a high-precision goniometer head at the SLS macromolecular crystallography beamlines

Automatic loop centring has been developed as part of the automation process in crystallographic data collection at the Swiss Light Source. The procedure described here consists of an optional set-up part, in which the background images are taken, and the actual centring part. The algorithm uses boundary and centre-of-mass detection at two different microscope image magnifications. Micromounts can be handled as well. Centring of the loops can be achieved in 15–26 s, depending on their initial position, and as fast as manual centring. The alignment of the sample is carried out by means of a new flexural-hinge-based compact goniometer head. The device features an electromagnet for robotic wet mounting of samples. The circle of confusion was measured to be smaller than 1 µm (r.m.s.); its bidirectional backlash is below 2 µm.

A versatile sample-environment cell for non-ambient X-ray scattering experiments

A compact reaction cell is described forin-situexperiments requiring control of both the temperature of the sample and the atmosphere over the sample. The cell incorporates an optional furnace capable of temperatures of up to ∼1273 K. The compact design and ability of the cell to mount directly on a standard goniometer head allows portability to a large number of diffraction instruments at synchrotron sources.

An improved goniometer head for high-temperature single-crystal X-ray diffraction

A reliable and inexpensive goniometer head has been designed. Its stability, resulting from its compact construction, makes it very suitable for accurate measurements. Moreover, its space-saving design facilitates its application in X-ray data collection using charge-coupled device (CCD) detectors. This head has been improved for high-temperature measurements and has been tested by comparison of accurate K0.88Rb0.12TiOPO4data collected both at room temperature and at 973 K on the same crystal. The excellent structure results obtained at 973 K during the 360 h of measurements prove the stability of the goniometer head.

A hinge goniometer head

A stable diffractometer goniometer head for mounting crystals enclosed in high-pressure cells, cryostats furnaces, or other heavy crystal-environment attachments, has been designed. Its construction is based on a hinge, thus it is called a hinge goniometer head, and allows adjustments in three directions. Under a load of 9.8 N perpendicular to the φ axis, the goniometer head yields less than 5 µm.

Magnetically coupled crystal holder and liquid-helium cryostat for X-ray four-circle diffractometer studies between 5 and 300 K

A new low-temperature system for X-ray four-circle diffractometer studies down to 5 K has been developed. The crystal is mounted on a new holder which is magnetically coupled to the diffractometer. This coupling is achieved by mounting a master magnet in place of the classical goniometer head. This master magnet drives a slave magnet fixed on the new crystal holder, and therefore the crystal is indirectly oriented by the master magnet. This magnetically coupled crystal holder (MCCH) is enclosed in a helium-flow cryostat which remains stationary during the φ, χ and to movements. The χ value is limited to ±65° and ω to 40° for a 150 mm diameter χ circle. All the tests and data collections (from 5 to 15 d) gave accuracies on the intensities, cell parameters and atomic positions identical to those obtained with a classical goniometer head. No frost problem occurs with this apparatus. The MCCH may also have applications in controlled-atmosphere, high-pressure or vacuum investigations.