The measurement of anomalous scattering near the GaKabsorption edge in GaP

Abstract

By the use of an SSD diffractometer and continuous X-rays, the energy dependences of Af' and Aft' values of Ga have been studied on GaP with energy resolution of about several eV around the Ga K edge; the values of Aft" were determined by the measurement of the absorption coefficient, and then the values of A f" have been obtained from the precisely measured ratio of Friedel-pair reflexions from a (111) single-crystal plate of polar GaP. Fine structures have been found in Aft" and therefore in A f" corresponding to those of the absorption coefficient. The present work has shown that the measured values of A f" more or less reasonably agree with the curves calculated from the dispersion relation.

Measurements of integrated intensity near the absorption edge with synchrotron radiation

“…The present authors hope to determine anomalous scattering factor values from the intensity ratio (Fukamachi & Hosoya, 1975;Hosoya, 1975) of the Friedel-pair reflexions obtained with SR X-rays. Moreover, they also hope to improve the energy resolution of the incident beam to 0-1 eV by using the (+, -) setting and to measure intrinsic reflexion profiles.…”

“…The energy dependence of the intensity thus obtained near the edge has been explained by the dynamical theory taking account of the absorption, as already published (paper I), and accordingly the intensity ratio of the Friedel-pair reflexions has also been explained (Fukamachi, Hosoya & Okunuki, 1976b, referred to as paper II). This ratio proved to be very useful for determining anomalous scattering factors near the edge (Fukamachi & Hosoya, 1975;Hosoya, 1975;Fukamachi, Hosoya, Kawamura & Okunuki, 1977, referred to as paper III). It is, however, difficult to keep the energy resolution constant by changing the slit system accordingly as the Bragg angle changes.…”

X-ray intensity measurements on large crystals by energy-dispersive diffractometry. I. Energy dependence of diffraction intensities near the absorption edge

“…The SSD diffractometer used has already been described Fukamachi & Hosoya, 1975); the diffraction tube was rotated while the SSD with a heavy cryostat was fixed. In the present work, a fine-focus Philips tube with Cr target was operated.…”

“…Another merit is the possibility of carrying out the measurements with radiations of desired energy values. This has already been utilized for a rapid determination of polarity sense (Hosoya & Fukamachi, 1973), and for experimental determination of anomalous scattering factors at the energy values near the absorption edge (Fukamachi & Hosoya, 1975). Including the latter, various possibilities of determining the anomalous scattering factors and phases of reflexions have preliminarily been reviewed (Hosoya, 1975).…”

“…at 30 kV and 40 mA. In order to get high energy resolution, two pairs of long collimators were used (Fukamachi & Hosoya, 1975). They are 30 cm long with a hole either 0.4 mm or 1 mm in diameter.…”