Buy article online - an online subscription or single-article purchase is required to access this article.
Download citation
Download citation
link to html
The present paper describes a newly built four-circle diffractometer for X-ray structure analysis with synchrotron radiation and particularly with the use of anomalous scattering due to a relatively heavy atom or atoms. This system is installed on beamline 10A in the Photon Factory (PF) in the National Laboratory for High Energy Physics, and its 2θ arm is rotated in the plane perpendicular to the floor. In this system, a one-crystal monochromator of the horizontal dispersion type is used. When the 111 reflection from a Si monochromator is used, the energy resolution is about 14 eV for X-rays of about 10 keV. The four-circle diffractometer, a monochromator and an alignment carriage for the four-circle diffractometer can be controlled by a computer and, therefore, once the optical system has been adjusted for X-rays of a certain wavelength then the diffraction intensity values from a single-crystal sample can be automatically measured at any wavelength chosen. An NaI(Tl) scintillation counter is used for both the intensity measurements of the diffraction beam and the monitoring of the incident-beam intensity. In order to make the counting rate high, 50 MHz counters are used for the above two intensity measurements. In this set-up, about 1% counting loss occurs at a counting rate of 55000 s−1. With this diffractometer, diffraction intensities have been measured for a hemimorphite single-crystal at two energy values on both sides of the Zn K absorption edge. The variation of the intensities, after being normalized by the standard reflection and the monitor counts, was somewhat large in comparison with the data measured in the usual laboratory. From these data measured at two energy values, a so-called two-wavelength anomalous-scattering difference Patterson function was calculated, where the Zn–Zn vector peaks were twice as high as in an ordinary Patterson.

Subscribe to Journal of Applied Crystallography

The full text of this article is available to subscribers to the journal.

If you have already registered and are using a computer listed in your registration details, please email support@iucr.org for assistance.

Buy online

You may purchase this article in PDF and/or HTML formats. For purchasers in the European Community who do not have a VAT number, VAT will be added at the local rate. Payments to the IUCr are handled by WorldPay, who will accept payment by credit card in several currencies. To purchase the article, please complete the form below (fields marked * are required), and then click on `Continue'.
E-mail address* 
Repeat e-mail address* 
(for error checking) 

Format*   PDF (US $40)
In order for VAT to be shown for your country javascript needs to be enabled.

VAT number 
(non-UK EC countries only) 
Country* 
 

Terms and conditions of use
Contact us

Follow J. Appl. Cryst.
Sign up for e-alerts
Follow J. Appl. Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds