For more information on selecting the optimal angle for ATR-SEIRAS, including polarization considerations, please see:
Sigrist, J. A., Lins, E. S., Morhart, T. A., Briggs, J. L., & Burgess, I. J. (2019). Optimization of a Commercial Variable Angle Accessory for Entry Level Users of Electrochemical Attenuated Total Reflection Surface-Enhanced Infrared Absorption Spectroscopy (ATR-SEIRAS). Applied Spectroscopy, 73(12), 1394–1402.Some points to consider:
- Only angles from 30° to 80° are accessible with the VeeMAX.
- Throughput is not constant as a function of angle.
- The beam spot size varies as a function of angle.
- The refractive index of a material is not in general constant as a function of wavenumber. The values chosen for the predefined crystal materials are approximately constant in the range of 5000 cm-1 to 1000 cm-1.
- Transmissivities account only for reflection losses, and do not include losses due to damping from the material such as phonon modes.
