Optical Specifications Of Cells - Agilent Technologies Cary 8454 Operator's Manual

4 Good Measurement Practices
General Considerations

Optical Specifications of Cells

The accuracy of the readings of a diode-array spectrophotometer is very
sensitive to spatial shifts of the measurement light beam. Cells having non
parallel opposite faces, or so called wedge shaped cells, lead to a spatial shift
of the light beam (see Figure 4). Therefore, the opposite cell walls illuminated
by the analysis light beam have to be very parallel. The parallelism is
measured in terms of the angle between the two opposite cell walls. We
recommend that you use 10 mm path length cells with an angle that is below
0.1 degrees of an arc.
Parallel
Cell Walls
Non-parallel
Cell Walls
Figure 4
54
Parallel
Cell Walls
Non-parallel
Cell Walls
Shift of the spectrophotometer light beam due to non-parallel cell walls
Agilent Cary 8454 UV-Visible Spectroscopy System Operator's Manual
Light Beam In
Light Beam in
Light Beam Out
Light Beam out
Light Beam In
Light Beam in
Light Beam Out
Light Beam out