IR- and Raman-Spectroscopic Microanalysis

Molecular spectroscopic microanalysis is used to obtain information about the chemical composition of the sample together with its magnified visual image. The diameter of samples measured by IR- and Raman microscopy is typically in the range from 50µm to 1cm. The achievable lateral resolution is dependent from the used measurement technique and the wavelength of the light that is absorbed and scattered by the sample, respectively.

Typical resolutions of the different techniques are:

• FT-IR Microscopy (HYPERION series): ~5 – 10 µm
• FT-IR Imaging (HYPERION 3000): ~1 - 5 µm
• FT-Raman Microscopy (RAMANScope III): ~5 µm
• Dispersive Raman Microscopy (SENTERRA): ~1 µm

Typical applications of FT-IR- and Raman-Microscopy are:

• Particle analysis
• Chemical determination of defects and contaminations
• Analysis of homogeneity and identity of coatings
• Chemical analysis of individual layers in multilayer systems (e.g. polymer laminates, paint chips)
• Distribution determination of different components in complex heterogeneous structures (e.g. biological tissues, tablets, polymers)

It depends on the individual sample composition and the particular analytical question, which of the different available molecular spectroscopic microscopy techniques is most suitable. For the measurement of particle and defects typically an FTIR-microscope of the HYPERION Series is used. To investigate polymer laminates or paint chips both, FTIR- and Raman-microscopes are suitable. Inorganic material often can be analyzed quite easily applying Raman-microscopy. To determine the distribution of different components in complex structures very quickly, FTIR-imaging is usually the best method (HYPERION 3000).

Like in macroscopic IR-spectroscopy the measurement modes transmission, reflectance and attenuated total reflectance (ATR) can be used for IR-microanalysis. As the ATR technique allows analyzing even non-transparent and non-reflecting samples without extensive sample preparation quick and easy, this method is applied very often. For the HYPERION an extremely powerful ATR-Objective is available, that allows the inspection of the sample with very high visual quality and stands out due to an exceptional IR-measurement sensitivity.

Very thin layers on reflective substrates are measured in grazing incidence reflection (GIR). For this type of measurements the HYPERION can be equipped with a Grazing Angle Objective (GAO) that even allows the analysis of (sub-) monolayers.