Inverse phi

Rigaku has implemented a version of the inverted phi-axis, conceived by Joseph Lidestri of Columbia University, for R-AXIS imaging plate area detectors. In this simple-yet-effective device for the mounting and recovery of frozen crystals, the standard phi-axis and microsope are mounted on an aluminum bracket so that the phi-axis hangs upside down. This bracket is mounted on the standard phi-axis positioning stage. Alignment of the phi-axis is the same whether inverted or not.

The inverted phi-axis eliminates the need for the speed and dexterity required for other flash-cooling techniques. These techniques involve cooling directly on the goniometer, cooling in liquid nitrogen and transferring the crystal, through room temperature air, to the goniometer, or using special tongs to transfer the crystal from liquid nitrogen to the goniometer.