Photon correlation spectrometry

Fig. 16.10 Plot showing kinetics of C CljNOj reduction (fiUed circles) occurring in conjunction with increasing photon correlation spectrometry (PCS) count rates (open circles), which are indicative of particle formation, in reaction with O.SOmM Fe(ll) (pH 7.0). (For clarity, the symbols showing measured values of [C CljNOJ are connected point to point.) The other open symbols show PCS count rates in nonreaction mixtures (i.e., without C Cl NO ) containing either O.SOmM Fe(II) (pH 7.0) or O.SOmM Ca(ll) (pH 7.0). Reprinted with permission from Klupinski TP, Chin YP, Traina SJ (2004) Abiotic degradation of pentachloronitrobenzene by Fe(ll) Reactions on goethite and iron oxide nanoparticles. Environ Sci Technol 3S 4353-4360. Copyright 2004 American Chemical Society...

The size and charge analysis was done using a Coulter DELSA 440SX (Coulter Beckman Corp., Miami, FL). This particular instrument measured the size distribution on the basis of photon correlation spectrometry (PCS) and was limited to particle diameters between 0.02 pm and 3 pm. Measurements were taken at four different angles simultaneously with 256-channel resolution each. Comparison of the spectra allowed for the detection of very small particles. The zeta potential was assessed on the basis of electrophoretic mobility (laser Doppler anemometry, LDA). This was defined as the particle velocity per unit of applied electrical field, with units usually given as pm s 1/V cm-1, while zeta potential is defined as the electrical potential between the bulk solution and the... 

The values thus estimated (Table 3.4) are in reasonable agreement with the hydrodynamic layer thicknesses on polystyrene latex measured by photon correlation spectrometry and ultracentrifugation [224]. 

Ferrimagnetic nanoparticles of magnetite (Fc304) in diamagnetic matrices have been studied. Nanoparticles have been obtained by alkaline precipitation of the mixture of Fe(II) and F(III) salts in a water medium [10]. Concentration of nanoparticles was 50 mg/ml (1 vol.%). The particles were stabilized by phosphate-citrate buffer (pH = 4.0) (method of electrostatic stabilization). Nanoparticle sizes have been determined by photon correlation spectrometry. Measurements were carried out at real time correlator (Photocor-SP). The viscosity of ferrofluids was 1.01 cP, and average diffusion coefficient of nanoparticles was 2.5 10 cm /s. The size distribution of nanoparticles was found to be log-normal with mean diameter of nanoparticles 17 nm and standard deviation 11 nm. 

A fundamental study was performed to demonstrate that flow FFF is a good alternative technique for the rapid measurement of protein diffusion coefficients [10]. The results obtained for 15 proteins were in good agreement (within 4%) with the literature data based on classical methods and a group of modern methods such as photon correlation spectrometry (PCS), laminar flow analysis, a chromatographic relaxation method, and analytical split-flow thin-cell (SPLITT) fractionation. The advantages of flow FFF are the high-speed separations and the calculation of D values directly from retention data. 

A 75/25 butadiene-styrene latex with a total sohds content of 68%, produced by cold emulsion polymerisation reaction and subsequently concentrated and evaporated, was incrementally fractionated through the technique of fractionated creaming with sodium alginate. The fractions were analysed in relation to the average particle size by photon correlation spectrometry. 13 refs. 

In recent years, in addition to theoretical developments, e.g., reptationW and tube theories,(i3,i4) iYiqyq have been many new analytical techniques,5) such as electron-induced X-ray fluorescence, the NMR field gradient method, forced Rayleigh scattering (FRS), forward recoil spectrometry (FRES), photon correlation spectroscopy, Rutherford back scattering. 

Electron spectrometry of atoms using synchrotron radiation has become an increasing and important field of fundamental physics within the last two decades. The increasing availability of dedicated facilities with tunable synchrotron radiation has allowed detailed exploration of the atom-photon interaction which must take into account the electron-electron interactions, usually termed electron correlations. The parallel experimental and theoretical developments have permitted rather sophisticated investigations of the response of the atomic many-electron... 

The ion mobility spectrum has many forms that share one common feature The ion current intensity is measured as a function of an ion s mobility in a gas. As with other types of spectrometry, the ion mobility spectrum is obtained by correlating a change in a spectrometer s parameter with a physical property of the ions. In light spectrometry, the number of photons is recorded as a function of photon energy in mass spectrometry, the number of ions is recorded as a function of mass, and in ion mobility spectrometry (MS), the number of ions is recorded as a function of an ion s collision cross section, which is related to its mobility. The type of IMS depends on the instrumental parameter that is scanned to produce the intensity versus mobility spectrum. To understand the many types of mobility spectra, we must first consider the relation among mobility, electric field, and pressure. 

With the introduction of fast-atom bombardment (FAB) in 1982, and matrix-assisted laser desorption/ ionization (MALDI) and electrospray ionization (ESI), most of the biomedical applications have been directed towards these methods. The 52( f.pD method has been found to have wide applicability, including the study of refractory materials, catalysts, semiconductors and frozen gases. Electronics capable of measuring the timing of events with subnanosecond resolution (the time it takes for a single photon to travel 1 cm) is used by this method as well as event-by-event data acquisition using the computer to make decisions at the molecular level, the basis of correlation mass spectrometry, a unique feature of 252Cf-PD. 

The aim of this talk is to review the results obtained in the studies of inner-shell ionization and decay by means of photoelectron (PES) and Auger electron spectrometry (AES). Since the scope of such a talk would be much too broad I will consider AES only in connection with photon or electron impact ionization. AES associated with ion-atom collisions, important for studies of multi-ionized atoms, will not be discussed. The angular anisotropy of photo- and Auger electrons will also not be treated in spite of the fact that for inner-shells the B-para-meter may depend sensitively on the structure and the dynamics of the atom, in particular for heavier atoms (e.g. Xe(4d) > ). Therefore my talk will be more selective than exhaustive. By means of selected examples of inner-shell photo and Auger electron spectra I will demonstrate the sort of information one can obtain for atoms. The main emphasis will be laid on effects caused by the electron correlation. Reviews on parts of this subject have been given earlier by Siegbahn et al. Krause >, Mehlhorn , Wendin and most recently by Siegbahn and Karlsson ... 

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