Transform Techniques in Chemistry: Past, Present, and Future

Abstract

Although the use of transform techniques in analytical chemistry and applied spectroscopy has only become widespread in the past five years, the history of this subject can be traced back to the middle of the nineteenth century when the effect of the interference of light was first used to derive spectroscopic information. In 1862, Fizeau⁽¹⁾ used Newton’s rings to show that the yellow sodium radiation was a doublet whose separation was 1/980 of their average wavelength. At the end of the century Michelson designed the interferometer, which now bears his name.^(2,3) The initial uses of this instrument for spectroscopic purposes concerned the determination of spectral profiles through the use of the visibility technique,⁽⁴⁾ which is essentially a study of the envelope of what we now call the interferogram. Rayleigh⁽⁵⁾ pointed out that a unique spectral distribution cannot be found from the visibility curve itself, and the Fourier transform of the interferogram is needed to calculate the spectrum unequivocally.