Self-beat techniques

Up to now, we have given a general theoretical development of the self-beat technique. As a practical illustration of the experimental apparatus used to detect autocorrelation functions in scattering experiments, the equipment currently used in our laboratory will now be described. While our treatment of the autocorrelation function has been in terms of an analog signal, the computer that measures this function is actually a digital device. This is based on the fact that it is also valid to count the scattered photons in order to calculate Ci(r) as the optical intensity signal is essentially determined by the number of photons that strike the photocathode per unit time. We have then... 

Eleven holograms were used to tune the desired modes from the laser. Each mode had a power of-13 dBm with a side-mode suppression of over 30 dB they were spaced 1.3 nm apart, as predicted by the performance of the tuneable filter calculations. The linewidth of the laser proved more difficult to measure, due to the fact that it was extremely narrow. A heterodyne self-beating technique was used with a delay line and a 100.6 MHz frequency shift. The use of a 14.6 km delay line yielded a linewidth of 1.7 kHz assuming a system resolution of... 

From the description presented here, it can be seen that self-beating spectroscopy as a technique for measuring the diffusion coefficient of... 

It appears noteworthy that it is in principle possible to obtain information on rotational diffusion coefficients from the self beating spectrum (the most frequently applied technique). In this case it is necessary to observe a (usually small) polarized component of the scattered light perpendicular to that of the normal scattering. Mazer, Benedek et al.143,144,145 in the US, Corti and Degiorgio29 in Italy have pioneered this method regarding its application to micellar phenomena in aqueous solutions. 

In this paper, optical techniques (Fabry Perot and self beating correlation) are first described and used to measure the viscoelastic parameters of 5P4E as a function of the pressure and temperature. These results represent an extension of the data available in the literature. Then, various rheological models for fluids behaviour in an elastohydrodynamic contact (E.H.D.) are described. 

Internationale Federation der WiderstandskSmpfer (ed.), Die SS-Henker und ihre Opfer, self-pub., Vienna 1965, p. 17 J.-C. Pressac, Auschwitz Technique and Operation of the Gas Chambers, Beate Klarsfeld Foundation, New York 1989, pp. 422, 424 J.-C. Pressac, Les Crematoires d Auschwitz, la Machinerie du meurtre de masse, Editions de CNRS, Paris 1993, Doc. 57 G. Schoenbemer, Der gelbe Stem, Rutten und Loening, Hamburg 1960, p. 162. 

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