Focusing optics for molybdenum radiation: a bright laboratory source for small-molecule crystallography

Abstract

This paper reports the design, installation and testing of a set of multilayer confocal mirrors in a side‐by‐side arrangement, built to increase the intensity from a molybdenum rotating‐anode X‐ray source. Ray‐tracing experiments were performed in order to evaluate the best design parameters for the system, which are shown to be a side‐by‐side configuration of 100 mm length. Measurements of the primary beam intensity show an increase by a factor of approximately five. Comparative data collections were performed which highlight significant enhancements in the derived crystal structure, arising from the increased intensity of the primary beam.

Changing and challenging times for service crystallography

“…New approaches to the measurement of diffracted intensities, such as Hybrid Pixel Detectors based on CMOS technology 18 will allow for faster and more sensitive data collection. The widespread use of focusing mirrors for chemical crystallography 19 has revolutionised X-ray generator technology for the routine service laboratory, particularly through microfocus sources. 20 New approaches through the use of liquid gallium as a target 21 are particularly promising for improving the dissipation of heat and thereby producing higher powered X-rays.…”

Comparison of silver and molybdenum microfocus X-ray sources for single-crystal structure determination

“…The curved mirror optics used by both Mo and Ag microsources deliver a narrow beam with a slightly anisotropic profile, making accurate sample alignment essential (Arndt, 1990;Coles & Hursthouse, 2004;Storm et al, 2004). The focal spot size of the beam is 110 and 90 mm for Mo K and Ag K, respectively (Hasse et al, 2010).…”

A comparison of a microfocus X-ray source and a conventional sealed tube for crystal structure determination

“…In contrast to total reflection mirrors (Arndt et al, 1998) and capillary optics (Hofmann et al, 2001), graded multilayer mirrors (Gö bel, 1982;Arndt, 1990;Jiang et al, 2002) can simultaneously focus and monochromate an X-ray beam. The development of graded multilayer mirrors for Mo K radiation (Storm et al, 2004;Coles & Hursthouse, 2004) provides an attractive alternative to the conventional sealed-tube sources with graphite monochromators that are still used for the majority of small-molecule single-crystal structure determinations, although their basic design, except for the introduction of capillary optics, has hardly changed for the past 50 years. The Incoatec Microfocus Source (ImS) employed in the experiments reported here combines graded multilayer mirrors with an air-cooled 30 W high-brilliance microfocus (sealed tube), resulting in a source characterized by a high flux density, high spatial resolution and high beam stability together with low power consumption and minimal maintenance.…”