Performance and Application of a New Planar Array Infrared Spectrograph Operating in the Mid-Infrared (2000–975 cm−1) Fingerprint Region

Abstract

A no-moving-part planar array infrared spectrograph (PA-IR) equipped with a 256 × 256 mercury cadmium telluride (MCT) focal plane array has been designed and constructed. The performance of the instrument, whose frequency range extends from 2000–975 cm−1, has been assessed in terms of resolution, bandwidth, and signal-to-noise ratio. The PA-IR spectrograph is able to record spectra with an 8.7 ms time resolution and has peak-to-peak noise levels as low as 2.4 × 10−4 A.U. As a demonstration of the potential of PA-IR, the dynamics of reorientation of a liquid crystalline sample exposed to a single electric field pulse has been studied. It was shown that PA-IR can be used for the simultaneous acquisition of two orthogonally polarized spectra. The advantages and limitations of PA-IR, step-scan Fourier transform infrared (FT-IR), and ultra-rapid-scanning FT-IR for real-time studies of reversible and irreversible phenomena are thoroughly discussed.