Microchimica Acta

doi: 10.1007/BF01201677pmid: N/A

Jacquinot, P.

doi: 10.1007/BF01201678pmid: N/A

Grasselli, Jeanette

doi: 10.1007/BF01201679pmid: N/A

Giacomo, Pierre

doi: 10.1007/BF01201680pmid: N/A

The apparatus that Michelson brought to the BIPM in 1892 to “determine the value of the metre in luminous wavelengths” has generated a vast family of instruments typically used for length measurement. Looking at them from this point of view teaches us a lot about the characteristics of the Michelson interferometer that make it specially convenient for Fourier transform spectroscopy (FTS). Michelson himself used the principle of the FTS to check the monochromaticity of various spectral lines. He was looking for a good standard of length, hence he did not care so much about the general problem of spectroscopy. Furthermore, he was limited to the parameter that he called the visibility of the fringes, i.e. the modulus of the Fourier transform of the spectral distribution, in fact the only parameter that the naked eye can roughly estimate, besides the fringe spacing. As he counted only up to 1212 fringes, and thereafter used a stepping process by “optical addition”, he did not worry about the optical defects that impair direct interferometric measurement of long distances. A few technological improvements have made the fringe-counting technique the current way of measuring length. It is shown that the analysis required for accurate length measurements with a Michelson interferometer is similar to the one required to make accurate FTS.

Cooley, James

doi: 10.1007/BF01201681pmid: N/A

The discovery of the fast Fourier transform (FFT) algorithm and the subsequent development of algorithmic and numerical methods based on it have had an enormous impact on the ability of computers to process digital representations of signals, or functions. At first, the FFT was regarded as entirely new. However, attention and wide publicity led to an unfolding of its pre-electronic computer history going back to Gauss. The present paper describes the author's own involvement and experience with the FFT algorithm.

Griffiths, Peter; Pentoney, Stephen; Pariente, Gilbert; Norton, Kelly

doi: 10.1007/BF01201682pmid: N/A

Most previous interfaces between a Chromatograph and an FT-IR spectrometer have been applicable to only one type of chromatograph-gas, liquid, or supercritical fluid. In this paper, the similarities and differences between various chromatography/FT-IR interfaces are described, and an interface which should be equally applicable to all three types of chromatography is proposed. In each case, the mobile phase is eliminated while the eluting components are condensed in a small area on a moving substrate. The spectra are then measured using an FT-IR microscope. The methods by which the mobile phase is eliminated depend on the nature of the chromatography, while the infrared sampling technique is determined by the nature of the substrate. The relative merits of transmission, reflection-absorption, diffuse reflection, and diffuse transmission spectrometry are discussed.

Mink, János

doi: 10.1007/BF01201683pmid: N/A

A brief summary of very recently published works on vibrational spectroscopic studies of adsorbed molecules (a) on metal single crystals or evaporated films with low surface area and (b) on supported metal catalysts or metal oxide catalysts with large surface area is presented here. So far as (a) is concerned some new results of EELS, reflection-absorption IR spectroscopy and IR emission spectroscopy (with cooled monochromator or interferometer) are discussed. With regards to topic (b) absorption by the support materials (SiO2, Al2O3, MgO, TiO2, etc.) usually prevents access to the region below about 1200 cm−1. Therefore we concentrate mainly on the methods (diffuse reflection, photoacoustic or emission spectroscopy) offering vibrational data in a wide frequency range. Some new developments in emission and FIR spectroscopy in our laboratory are discussed.

Chase, Bruce

doi: 10.1007/BF01201684pmid: N/A

The basic experimental aspects of Fourier transform Raman Spectroscopy are reviewed with an emphasis on detector technology. The sensitivity is comparable to dispersive Raman Spectroscopy using visible lasers. The ease of spectral subtraction is demonstrated and examples are given showing the elimination of fluorescence.

Nafie, Laurence; Lee, Nam-Soo; Paterlini, Germana; Freedman, Teresa

doi: 10.1007/BF01201685pmid: N/A

Polarization modulation Fourier transform infrared spectroscopy can be measured by either double modulation FTIR or interferometric modulation FTIR techniques. The principles of both techniques are presented with examples of representative measurements. The relative advantages and disadvantages of each method are compared.

Birch, James

doi: 10.1007/BF01201686pmid: N/A

A review is presented of recent developments in the methods of dispersive Fourier transform spectroscopy that have demonstrated the unique value of this broad band method for determining the optical constants of gases, liquids and solids.