Experiments with Fourier transform spectrometry of Nafion, a water-swollen polymeric membrane, are described. The transmittance spectra of liquid samples and Nafion, soaked in these samples, were studied, depending on the deuterium content in water in the spectral range 1.8-2.15 μm. The experiments were carried out using two protocols: in the first protocol we studied the dynamics of Nafion swelling in HO + DO mixtures for the deuterium concentrations 3 < C < 10 ppm, and in the second protocol we studied the dynamics of swelling in pure heavy water (C = 10 ppm). For liquid mixtures in the concentration range 3 < C < 10 ppm, the transmittance spectra are the same, but for Nafion soaked in these fluids, the corresponding spectra are different. It is shown that, in the range of deuterium contents C = 90-500 ppm, the behavior of transmittance of the polymer membrane is non-monotonic. In experiments using the second protocol, the dynamics of diffusion replacement of residual water, which is always present in the bulk of the polymer membrane inside closed cavities (i.e., without access to atmospheric air), were studied. The experimentally estimated diffusion coefficient for this process is ≈6·10 cm/s.

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Infra-red Fourier spectroscopy is known to be very effective in detecting spectral features of biological objects during fermentative and photochemical transformations of their structure [1,2). However, in the case of ordinary single-channel measurements, the parameters of the instrument and samples involved must exhibit very stability. In fact, two consecutive recordz of a single-channel spectrum differ due to drift of intensity of the light source, to instability of the interferometer and detectors, to fluctuation of medium, etc.Also, the samples are unstable.The methods are known to improve long-term stability of a Fourier spectrometer (3), but they are very expensive. We think to be more acceptable to build two-channel Fourier spectrometers which make use of compensation (their principles were developed by Genzel [4)).In Central Bureau for Unique Instrumentation of Academy of Science of the USSR we have developed a two-channel Fourier spectrometer, named FS-02, for precise measurements of spectra of biological and similar objects characterized by presence of intense and timevariable background. This instrument (see Fig.I) possesses the following parameters: spectral range 400 to 4000 cm-I spectral resolution I cm-I deviation of a line of IOOZ transmission 0 . 0 I X signal-to-noise ratio in one scan 5 0 0. In order to illustrate the potentialitiep of the instruments, we show in Fig.2 and Fig.3 the lines of 100Z transmission recorded in single-channel and two-channel modes respectively. Fig.4 demonstrates the spectrum of CaF2 and Fig,5 shows the spectrum of bactero-182 / SPIE Vol. 1575 8th International Conference on Fourier Transform Spectroscopy(1991) O-8194-0706-2/92/$4.OO Fig.I. Schematic diagram of the FS-02. Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/24/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx

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