The five circle diffractometer at HASYLAB: Recent developments

Single-crystal diffraction data of dodecasil 1H (D1H), a clathrasil (SiO2) with 1-aminoadamantane and NH3 as guest molecules, were collected from a small crystal (V = 2.5 × 105 lxm 3) with synchrotron radiation (SR) (A =0.78914~) at the five-circle diffractometer of HASYLAB (DESY, Hamburg, Germany). The space group is P6/mmm with a = 13.826 (3), c = 11.186 (3) A,, V = 1852 (1) A 3, the content of the unit cell is 34SiOdCIoHIsNHz)5NH3, F(000) = 1154, Dx = 2.043 g cm-3, Mr = 2278.4 g mol-1. The structure refinement is based on 784 unique reflections (R = 2.62%, wR = 1.76%). The results are compared with studies using a conventional X-ray source. All O-atom sites were found to be split (average O---O distance 0.5 A) indicating a disorder of the SiO2 host framework. The mean Si--O distance, Si--O---Si angle and Ueq (oxygen) from anisotropic refinement without splitting were 1.568 A, 170.7 °, 0.065 A 2, respectively, changed to 1.596 (11)

Section: Methodsmentioning

confidence: 99%

A study of disorder in the SiO₂ host lattice of dodecasil 1H using synchrotron radiation

Miehe¹,

Vogt²,

Fueß³

et al. 1993

“…Data collection was carried out on the five-circle diffractometer at HASYLAB beamline D3 (Kupcik, Wendschuh-Josties, Wolf & Wulf, 1986;WendschuhJosties & Wulf, 1989) during dedicated shifts of the DORIS II storage ring. Average fills lasted up to a maximum of 3 h, with ring currents between 100 and 40 mA.…”

Section: Methodsmentioning

confidence: 99%

Accurate structure analysis with synchrotron radiation. An application to borazone, cubic BN

Eichhorn¹,

Kirfel²,

Grochowski³

et al. 1991

“…The measurements were performed on a Huber fourcircle goniometer at the HASYLAB beamline D3 (Kup~ik, Wendschuh-Josties, Wolf & Wulf, 1986;Wulf, Almen & Wendschuh-Josties, 1991). The wavelength was tuned by a silicon (111) (Bilderback, 1975).…”

Section: Methodsmentioning

confidence: 99%

Determination of the anharmonicity constant of GaAs by means of the Bijvoet relation of the weak (666) reflection

Pietsch¹,

Paschke²,

Eichhorn³

1993

As a result of the influence of anomalous dispersion the weak (hhh) and (hhh) reflections of the zinc blende structure differ from each other. At large scattering vectors this difference, described by the Bijvoet relation B, depends solely on the size of the anharmonic force constant /3. It can be determined by measuring B near the K-absorption edge of any constituent. This experiment was performed for the (666) and (666) reflections of GaAs between A = 0.90 and 0.97 A, using synchrotron radiation. Outside the extended X-ray absorption fine-structure spectroscopy region the integrated intensities decrease in a different manner with increasing A for both reflections measured at 'umweganregung' free azimuthal positions. Under the assumption of/3Oa = --/3As and using the measured wavelength dependence of B, the anharmonicity constant is evaluated to /3 = -1.75 (0.15) × 10-17j •-3 which is nearly the same as that for germanium.