Goniometer vertical axis

The orientation of both the goniometer axis and specimen surface (or specimen axis) with respect to the horizon, i.e. they may be located in a vertical or horizontal plane. 

Figure 3.7. Horizontal (left) and vertical (right) orientations of a flat sample. The location of the goniometer axis is shown using a dash-double dotted line with small filled circles at the ends. The dashed line indicates the location of the optical axis, which is the line connecting the focus of the x-ray tube, the receiving slit and the sample surface in the reflection geometry, or the sample center in the transmission geometry at 0 = 20 = 0°.

The orientation of the sample usually establishes the orientation of the goniometer axis, i.e. the axis around which both the detector and sample (or both the detector and x-ray source) rotate in a synchronized fashion during 0-20 or 0-0 data collection. A horizontal sample orientation implies that the goniometer axis is located in the horizontal plane, and a vertical sample orientation makes the goniometer axis vertical, as depicted in Figure 3.7. 

Figure 3.14. The schematic of a powder diffractometer with the vertical goniometer axis, cylindrical sample in the transmission mode and a curved position sensitive detector (PSD). Solid arrows indicate the incident beam and broken arrows indicate the diffracted beams pathways. F - focal point of the x-ray source, M - monochromator, DS - divergence slit, T -incident beam trap.

An alternative method is to mount the crystal in a precise orientation and to use the 0-axis to explore the blind region of the single rotation axis. It is feasible to place the capillary containing the sample in a vertically upright position via a 135° bracket mounted on the goniometer... 

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