Polystyrene autocorrelation function

Fig. 6.12. A Typical CARS signal trajectory revealing the particle number fluctuations of 110-nm polystyrene spheres undergoing free Brownian diffusion in water. The epi-detected CARS contrast arises from the breathing vibration of the benzene rings at 1003cm 1. B Measured CARS intensity autocorrelation function for an aqueous suspension of 200-nm polystyrene spheres at a Raman shift of 3050 cm-1 where aromatic C-H stretch vibrations reside. The corresponding translational diffusion time, td, of 20 ms is indicated. (Panel B courtesy of Andreas Zumbusch, adapted from [162])...

The analysis of the autocorrelation function data by the Coulter Model N4 is carried out by the Size Distribution Program (SDP), which gives the particle size distribution in the form of various output displays (see Section 10.4). The SDP analysis utilizes the computer program CONTIN developed by S.W. Provencher (ref. 467-470 see also Section 10.2). (This program has been tested on computer-generated data, monomodal polystyrene samples, and a vesicle system (ref. 466-468,471).) Since the SDP does not fit to any specific distribution type, it offers the ability to detect multimodal and very broad distributions. 

Polystyrene Spheres. As an initial exercise. Excel should be used to calculate the autocorrelation function giqAt) from PS data obtained using = 10,000. In Excel, a calculation equivalent to that of Eq. (11) can be done by placing the raw data values in cells A1 to AlOOOO. With nothing (or 0) in cells AlOOOl to A20000, one can calculate gj xa column B by entering in cell B1 the formula... 

Three of the experiments are completely new, and all make use of optical measurements. One involves a temperature study of the birefringence in a liquid crystal to determine the evolution of nematic order as one approaches the transition to an isotropic phase. The second uses dynamic laser light scattering from an aqueous dispersion of polystyrene spheres to determine the autocorrelation function that characterizes the size of these particles. The third is a study of the absorption and fluorescence spectra of CdSe nanocrystals (quantum dots) and involves modeling of these in terms of simple quantum mechanical concepts. 

FIGURE 34-6 (a) Scattered radiation intensity fluctuations from an aqueous solution of 2.02-pm (diameter) polystyrene spheres, (b) autocorrelation function of intensity fluctuations. 

Figure 3.18. Example of autocorrelation functions giG) and gi(T) obtained in DLS measurements at four scattering angles for a dilute solution of polystyrene in toluene. The two autocorrelation functions differ in the ordinate scale only.

Figure 12.13 Intensity autocorrelation function obtained for a randomly cross-linked network of polystyrene swollen in cyclohexane at 308 K...

Aggregation process, 132, 213 Amorphous polystyrene (a-PS), gelation, 191-2 Angular frequency, 322 Anisotropically shaped gels, 89-90 Anomalous viscosity, 112 Arginic acid salt, 114 Atago refractometer, 395, 397 Atomic force microscopy (AFM), 221, 235-49 application to gels, 245-7 fundamental principles, 242-4 Autocorrelation function (ACF), 195, 205... 

Figure 3.12 presents an autocorrelation function recorded with a solution of a polymer blend consisting of equal parts of almost monodisperse polystyrene and PMMA that exhibits a single exponential decay. 

ABSTRACT - The fluorescence anisotropy decay (FAD) technique is first described, then the different expressions ich have been proposed for the orientation autocorrelation function (OACF) of polymer chains are presented. Typical FAD curves of dilute and concentrated solutions of polystyrene labelled with an anthracene group in the middle of the chain are compared to the various OACF expressions and discussed. In the case of bulk polybutadiene, FAD results obtained either on anthracene labelled chains or on 9,10 dialkylanthracene probes free in the polymer matrix, show that the same type of OACF as for polymer solutions can account for the experimental data. Besides, the temperature dependence of the correlation time of the labelled polybutadiene appears to agree with the WLF equation derived from macroscopic viscoelastic measurements, proving that the segmental motions of about 20 bonds which lead to the FAD of labelled polybutadiene participate in the glass transition processes of this polymer. 

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