Very strong absorption

: Crystal structure of Murdochit

Within the same two-theta limit of ~54º a much higher number of reflections is accessible using the APEX II QUAZAR equipped with the 30 W Silver IμS. The shortest wavelength available for an in-house SC-XRD system provides an improved parameter/reflection ratio. In consequence an anisotropic refinement of the O and Cu atoms became possible. Lower absorption results in a superior signal to noise ratio of the silver data. Residual density peaks in the high-resolution Ag data set are obtained from the conventional monopol-refinement model and contain valuable information on the electron distribution within the chemical bond.

Cu₆ PbO₇(Cl,Br)	APEX II QUAZAR	APEX II QUAZAR	APEX II QUAZAR
Source	Mo-IμS	Ag-IμS	Ag-IμS
Sample Size [mm³]	0.12 x 0.09 x 0.06
Absorption Coefficient μ [mm^-1]	38.4	20.6	20.6
Exposure time [s/°]	67	67	67
Max. resolution [Å]	0.77	0.77	0.61
Unique data	69	69	127
No. of refined parameters	9	9	12
<I/sig>	187,7	216,6	186,8
R1	0,0198	0,0179	0,0176
wR2	0,0551	0,0503	0,045
Fo-Fc (highest/lowest peak)	0.75 / -0.83	0.79 / -0.76	2.12 / -1.15
Bond length Pb1 - O1	2.294(6)	2.293(6)	2.290(3)

Sample courtesy of Dr. Th. Malcherek, Hamburg University, Institute of Petrography and Mineralogy

More Information

Accessories for Chemical Crystallography

APEX Software

APEX II CCD Detector

3-circle goniometer

4-circle Kappa goniometer