Correlation spectrometers

The third activity is the evolution of a research instrument into a low-cost instrument that requires a minimum degree of skill to use. An excellent example of this process is the transformation of research-grade photon correlation spectrometers into low-cost, easy-to-use, limited-function instruments for routine analysis applications. 

Fig. 10.18 Block diagram of a fixed angle photon correlation spectrometer [284]...

It is important to point out that neither approach attempts a direct measurement of the arc He flux. To estimate magma production rates, scaling is used in the first instance, whereas the second methodology relies on knowledge of an absolute flux of some chemical species from volcanoes together with a measurement of the ratio of that species to He. The most widely used species to derive absolute chemical fluxes from subaerial volcanoes is SO2 using the correlation spectrometer technique (COSPEC) (Stoiber et al., 1983). Carbon dioxide (see Brantley and Koepenick, 1995) and Po (Marty and LeCloarec, 1992) have also been used in an analogous manner. 

Fig. 5.5 Schematic setup of a fluorescence correlation spectrometer. A beam of parallel laser light is focused by an immersion objective onto a fluorescent sample. The fluorescence of molecules traversing the focus is collected by the same objective. It is filtered, focused, and detected. Signal autocorrelation is carried out by the computer (PC).

Photon Correlation Spectroscopy (PCS). A Malvern model 4300 photon correlation spectrometer with a 64 channel type K7027 Loglin correlator was used in conjunction with a Liconix He/Cd laser operating at 441.6 nm. The temperature was controlled to 0.1°C. 

Stoiber, R. E., and G. Bratton (1978). Airborne correlation spectrometer measurements of S02 in eruption clouds from Guatemalian volcanoes. EOS Trans. AGU 59, 1222. 

Stoiber RE, Malinconico LLJ, Williams SN (1983) Use of the correlation spectrometer at volcanoes. In Forecasting volcanic events. Tazieff H, Sabroux J (eds) Elsevier, New York 1 425-444. 

PCS measures the diffusion coefficient of particles in the size range between 3 nm and a few micrometres. Particle size measurements for particles and/or aggregates smaller than 1 pm were performed on a Malvern Photon Correlation Spectrometer (PCS) Autosizer 4700 (633 nm, 5 mW, He-Ne laser). It is essentuial to use a red laser due to the fluorescence spectra of the humic substances (Goldberg and Weiner (1989)). A round quartz cell was used and temperature adjusted to 25 C. The method measures the diffusion coefficient (Brownian motion) of particles and is limited to about 3 nm... 

The one-dimensional angular correlation spectrometer is a relatively simple equipment (O Fig. 27.4). It is constructed from two scintillation detectors, several slits, a coincidence unit, and a storage unit. 

Although the scheme of an angular correlation spectrometer is simple, due to the very small angles measured, its actual construction is intricate. Very narrow slits, long source/detector distances (several meters), precise positioning of the mobile detector, and an intense source... 

The first age-momentum correlation (AMOC) measmements were performed more than 20 years ago (McKenzie and McKee 1976 Kishimoto et al. 1982a, b). Those measurements applied Na sources and measured, in fact, the energy dependence of lifetime spectra. The electronics of those days resulted in a much worse resolution of these age-momentum correlation spectrometers than that of individual lifetime and Doppler-broadening spectrometers. In spite of the bad resolution, these measmements provided valuable information about, for example, the structure of certain solutions (Kishimoto et al. 1982b). 

FRACTIONATION CREAMING WITH SODIUM ALGINATE OF A BUTADIENE-STYRENE LATEX AND PARTICLE SIZE CHARACTERIZATION BY QUASI-ELASTIC LIGHT SCATTERING USING PHOTON CORRELATION SPECTROMETER Macedo C M B Oliveira C M F Rio de Janeiro,Universidade Federal... 

T.V. Ward, H.H. Zwick Gas cell correlation spectrometer GASPEC. Appl. Opt. 14, 2896 (1975)... 

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