The KSV NIMA PM-IRRAS is the first infrared spectrometer made specifically for IR analysis of monolayers floating on an aqueous sub-phase or deposited on reflective substrates. It is a highly sensitive and very surface-specific instrument
enabling measurements in ambient conditions. The innovative goniometric configuration allows easy angle adjustment and fast setup.

Features & Benefits

  • KSV NIMA PM-IRRAS is based on the polarization modulation IR absorption technology that makes it possible to characterize both chemical composition and molecular orientation of even single-molecule thin layers.
  • Specifically designed for Langmuir film characterization. The system has easy integration with KSV NIMA L & LB Troughs enabling characterization with controlled surface pressure and molecular packing. KSV NIMA PM-IRRAS is suitable for characterizing both floating monolayers on the liquid surface and nanoscale solid surfaces.
  • The instrument has an user-friendly and open design with simple angle (40°-90°) and height adjustments. It takes only minutes to setup an experiment and easy to combine with external UV light source, heater or other complementary equipment.
  • The polarization modula­tion method eliminates background signals from environmental factors such as water vapor and CO2. There is no need for protective gasses or having the optical part of the FTIR spectrometer in vacuum. It also allows longer measurement times, because changes in the light source intensities or water surface height changes do not affect the final spectrum.
  • The possibility to do transmission measurements.


The infrared absorption of the PM-IRRAS is in the range of 800-4000 cm-1, making it possible to detect the following:

  • Chemical composition of thin films. Chemical composition can be detected from thin films that are just one molecule thick.
  • Molecular-scale quantitative analysis of molecular orientation. The orientation changes of molecules at the air-water interface or at reflective solids can be detected from the PM-IRRAS peak intensity. This enables, for example, observation of the effect of Langmuir film packing density as well as Langmuir Blodgett coating orientation.
  • Adsorption/desorption and surface reactions in mono- and multilayers. Studying interaction of biomolecules using cell membrane models can provide means to understand reactions related to drug delivery and the membrane behavior itself. These kinds of model systems are employed in several application areas, such as drug development, food technology, and biological and biochemical research.
  • Phase transitions in thin films. Monolayer phase transitions can be detected with PM-IRRAS. A typical example would be protein denaturation at the interface or deposited layer.
  • Hydration/hydrogen bonding. The PM-IRRAS peak position shifts dramatically when the hydration stage changes. This allows the observing of a film’s structural response due to changing external condition such as pH or temperature.

Product details

KSV NIMA PM-IRRAS is a state-of-the-art compact Fourier Transform IR-spectrometer. By positioning the spectrometer and detector on a goniometer above the surface the experimental setup is greatly simplified and provides results within minutes instead of days. The open design allows combined use of other comple­mentary equipment such as external UV light sources and heating. The instrument can be positioned above a fully equipped analytical KSV NIMA Langmuir Trough, facilitating accurate monolayer studies without restrictions.


PM-IRRAS technology allows the measurement of surface specific FT-IR spectra in materials by recording the differences in the reflection of p- and s-polarized light from interfaces enabling detecting chemical compositions and molecular orientation from interfacial films down to films one molecule thick.

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