Grazing Angle Objective
The measurement of very thin coatings on metallic surfaces often requires the grazing angle incidence reflection technique. It enhances the interaction of the infrared light with the sample. Bruker’s patented* grazing angle objective (GAO) achieves very high sensitivity due to the novel use of a folding mirror and dual pass design. The signal intensity is actually doubled during the GAO analysis because the IR beam passes through the sample twice.
Unlike other grazing angle objectives, polarization of the incident light is retained. This property facilitates selective measurements of the absorption of p- and s-polarized light, from which information about the sample orientation can be obtained.
*US 6008936
Example of the sensitivity of the HYPERION Grazing angle-objective:
The figure shows IR-spectra of a monomolecular alcyl-thiol-layer on gold. The upper spectrum was measured on a sample area of ca. 100 x 100 µm and the middle one on an area of about 50 x 50 µm. Measurement of 25 x 25 µm of the sample results in the lowest spectrum. Here the measured sample amount is below one pico gram!
Properties GA-Objective
- Contact free analysis of very thin layers down to (sub-)monolayers
- Highest measurement sensitivity due to patented Dual Pass Design
- Polarization dependent measurement possible
- Very high light throughput and high numerical aperture (NA=0,995)
