PAIR spectroscopy brings new capabilities beyond FTIR

Researchers at the University of Delaware and PAIR Technologies (both in Newark, DE) have developed a planar-array IR (PAIR) spectroscopy instrument that performs at a level not possible with Fourier-transform IR (FTIR) technology in terms of speed, reproducibility, and convenience. Most significantly, data can be acquired in fractions of seconds compared to minutes, with the added bonus that a double-beam PAIR technique can also minimize the effects of atmospheric interference, allowing operation of the instrument without the need for nitrogen or other pure-gas purge. In addition, the spectrometer can operate for days with miniscule instrument drift.

In PAIR spectroscopy, a focal-plane array normally cooled by either liquid nitrogen or a Stirling cooler is used in conjunction with dispersive optics to acquire absorbance information. A dark image (spectrograph blocked off with a room-temperature plate) is obtained once when setting up the instrument. A sample image with the sample inserted in the beam path and a reference image of the beam only are obtained simultaneously at a rate of 100 Hz or more. The beam path consists of several mirrors and a diffraction grating. Data comparisons between PAIR and FTIR spectroscopy confirm that PAIR technology can provide a 10× to 100× sensitivity improvement in the detection of proteins in water and comparable spectral resolution and signal-to-noise ratio for the spectra of polystyrene in the carbon-hydrogen stretching region. The real benefits of this instrument will be in the investigation of nonrepeatable events and long-time studies. Contact Jim Malone at [email protected].

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