Other Infrared (IR) Transform Spectroscopies

T. Hirschfeld

doi:10.1117/12.932196

29 October 1981 Other Infrared (IR) Transform Spectroscopies

T. Hirschfeld

Proceedings Volume 0289, 1981 Intl Conf on Fourier Transform Infrared Spectroscopy; (1981) https://doi.org/10.1117/12.932196
Event: 1981 International Conference on Fourier Transform Infrared Spectroscopy, 1981, Columbia, United States

Abstract

Profiting from the example of Fourier transform spectroscopy, a number of possible other transform spectroscopies, such as Hadamard, Walsh, and Laplace transforms, have been investigated. A number of other transforms show spectroscopic promise in the IR. (1) CHIRP. Here a tunable laser is coupled via a beamsplitter to a spatially extended sample and a heterodyne detector. The audio frequency output of the latter after chirp transformation yields a range resolved signal useful for remote measurements or nonuniform sample measurements. (2) KRAMERS-KRONIG. This transform, for which a simplified fast calculating procedure has evolved in the Fourier domain, interconverts refraction and absorption spectra. Refractive index spectra offer advantages for tunable laser work, can be used for absorption spectrum correction, and can be conveniently obtained by asymmetric FT-IR. (3) ABSORBANCE NONLINEARITY. Particle size or shape, thickness, or concentration distributions within an inhomogeneous sample can be calculated from line shape distortions produced by the energy nonlinearity of the absorption process. Other transforms of potential ability, such as the Hankel, the equiabsorbance, and two dimensional Fourier transforms, will be briefly mentioned.

Citation Download Citation

T. Hirschfeld "Other Infrared (IR) Transform Spectroscopies", Proc. SPIE 0289, 1981 Intl Conf on Fourier Transform Infrared Spectroscopy, (29 October 1981); https://doi.org/10.1117/12.932196

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