Photon Correlation Spectroscopy of Polydisperse Samples

Fletcher, Guy C.; Ramsay, Donald J.

doi:10.1080/713821331

Cited by 24 publications

(8 citation statements)

References 12 publications

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“…The autocorrelation functions were analyzed by the 2nd order cumulants [25], CONTIN [26,27], and EXPSAN [28] v3.0 programs, included in the BI-ZP Brookhaven software package. The former algorithm calculates mean diameters and polydispersity indexes for the scattering particles, whereas the latter two give diameter distribution functions.…”

Section: Dynamic Light Scattering (Dls)mentioning

confidence: 99%

Time evolution of the thermotropic behavior of spontaneous liposomes and disks of the DMPC–DTAC aqueous system

Viseu¹,

Correia²,

Fernandes³

2010

Journal of Colloid and Interface Science

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Section: Dynamic Light Scattering (Dls)mentioning

confidence: 99%

Time evolution of the thermotropic behavior of spontaneous liposomes and disks of the DMPC–DTAC aqueous system

Viseu¹,

Correia²,

Fernandes³

2010

Journal of Colloid and Interface Science

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“…For a noise level E( 2 ) =10 -4 on g(2)(t) with n = 2, for example, E)(t) ranges from 0-625 x 10 -4 to 118 x 10 -4 . We have used the maximum value of E (1 ) (t) to estimate the expected values of coma x using equation (10) at each of three polydispersities and three noise levels. These values of (Oax are given in table 2.…”

Section: Discussion Of Resultsmentioning

confidence: 99%

“…using a weighted linear least-squares program [1] based on the algorithm of Gentleman [6] to recover the (k -1) amplitudes A i . Typically, three to six steps can be fitted successfully, depending on the level of noise on the data.…”

Section: Fitting Histogram Stepsmentioning

confidence: 99%

“…In a recent paper [1], hereafter called I, we described a method of analysing on a desk-top computer (Hewlett-Packard 9835A) data from light-scattering experiments on polydisperse solutions of scatterers, using exponentially spaced histogram steps to describe the distribution function of decay rate y. The method is based on a proposal by McWhirter [2] and Pike [3], subsequently developed and applied by Ostrowsky et al [4] using a -function representation.…”

Section: Introductionmentioning

confidence: 99%

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Photon Correlation Spectroscopy of Polydisperse Samples: II. Optimal choice of histogram parameters with exponential sampling

Fletcher

Ramsay

1986

Optica Acta: International Journal of Optics

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The use of a histogram model of the distribution function of decay rates in the analysis of light-scattering data from polydisperse samples is investigated. Histograms having a wide range of step sizes and number of steps have been fitted to computer-generated data of various polydispersities and noise levels. These histograms have been compared with the original distributions to determine the optimum histogram parameters in each case. The parameter omax, which determines step size, decreases linearly with increasing In (noise) but only at about half the rate predicted by the theory of McWhirter and Pike. Wmax also decreases with increasing polydispersity. The number of steps is determined, as expected, by the step size and the need for the histogram to span fully that part of the distribution function which contributes to the autocorrelation function at a level above noise. IntroductionIn a recent paper [1], hereafter called I, we described a method of analysing on a desk-top computer (Hewlett-Packard 9835A) data from light-scattering experiments on polydisperse solutions of scatterers, using exponentially spaced histogram steps to describe the distribution function of decay rate y. The method is based on a proposal by McWhirter [2] and Pike [3], subsequently developed and applied by Ostrowsky et al.[4] using a -function representation. In our method different histograms, obtained by systematically varying the step positions, are overlaid to smooth the recovered distribution function. In the present paper we discuss as functions of polydispersity and noise level, the optimal choice of the 'centre' of the histogram (), the number of knots (k) or steps (k -1), and the parameter .)max that determines the step size. These three parameters conveniently describe the span of the histogram that is most appropriate to a particular distribution, We also comment on the choice of a suitable sample time for each channel of the autocorrelator used to collect the data.As in I we have made use of computer-generated data of precisely known characteristics, in order to facilitate a proper comparison between the original distribution of decay rates and the histogram distribution recovered by the fitting procedure. The results of such a comparison are intended to provide a set of working rules which may be used with experimental data of unknown distribution. In the data analysis we again restrict ourselves deliberately to linear routines that can be implemented on a desk-top computer.

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“…The v's become vectors rather than functions and a weighting is introduced to reflect varying data accuracy. (4) We discuss here two extensions to the method. The first of these is a step towards fully automatic implementation on a small desk top computer.…”

Section: Introductionmentioning

confidence: 99%

Polydispersity Analysis In Photon Correlation Spectroscopy (PCS) Experiments

1987

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We discuss two modifications to the profiled singular function method for inversion of multi -exponential data obtained in PCS experiments. The first is a rapid inversion involving look -up tables.The second incorporates the scattered intensity form factor into the profile to allow direct calculation of the particle radius -mass distribution. AbstractWe discuss two modifications to the profiled singular function method for inversion of multi-exponential data obtained in PCS experiments. The first is a rapid inversion involving look-up tables. The second incorporates the scattered intensity form factor into the profile to allow direct calculation of the particle radius-mass distribution.

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Photon Correlation Spectroscopy of Polydisperse Samples

Cited by 24 publications

References 12 publications

Time evolution of the thermotropic behavior of spontaneous liposomes and disks of the DMPC–DTAC aqueous system

Time evolution of the thermotropic behavior of spontaneous liposomes and disks of the DMPC–DTAC aqueous system

Photon Correlation Spectroscopy of Polydisperse Samples: II. Optimal choice of histogram parameters with exponential sampling

Polydispersity Analysis In Photon Correlation Spectroscopy (PCS) Experiments

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