By means of infrared spectroscopy vibrational and rotational states of molecules are excited. One can determine the chemistry of the functional groups like hydroxides, carbonates, sulfates, esters and so on. The IRRAS technique is used for surfaces, whereby the IR beam measures in grazing incidence to the surface. In addition polarization modulated light can be used to get a very high sensitivity for thin films or organic monolayers on metal surfaces. Another advantage of PM-IRRAS (Polarisation modulated infrared reflection absorption spectroscopy) is that bands of atmospheric water and carbon dioxide can be eliminated.
Specifications
- Vertex 70v spectrometer with attachments for ATR-IR and reflexion measurements
- Measurement of surfaces with grazing incidence from 10-90° (IRRAS)
- Additional use of polarisation modulated light for better sensivity (PM-IRRAS)
- In situ measurements in weathering cell possible
- Spectral range 650 – 8000 cm−1 with PM module
- Standard resolution: up to 0.4 cm−1
- Wavelength accuracy: better than 0.01 cm-1 at 2000 cm−1
Applications:
- Investigation of submonolayers, monolayers and other ultrathin coatings on metallic surfaces (with limitations even without the need for a reference sample)
- Corrosion processes
- Elimination of water vapor absorption (PMA 50 XL)
Sample requirements:
- Size up to 100 x 200 mm, optimal 20 x 30 mm and planar
- Coated foils and round samples can also be measured
Development of sulftic- and sulfatic corrosion products on a zinc surface. Weathering at 80% RH and room temperature. Measurements every 15 min. One recognizes a steady band growth.
