Data analysis in frequency-domain fluorometry by the maximum entropy method — recovery of fluorescence lifetime distributions

Brochon, Jean‐Claude; Livesey, A. K.; Pouget, Jacques; Valeur, Bernard

doi:10.1016/s0009-2614(90)87189-x

Cited by 63 publications

(59 citation statements)

References 16 publications

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“…24 The decays were repeated at least four times, and the average value of the decay times and amplitudes were then used in posterior data analysis. Maximum entropy method 25 (MEM) analyses were made for decays collected at 415 nm (polyfluorene emission), with more than 5 × 10 4 counts accumulated in the channel of maximum counts, using a noncommercial software package. All measurements were done using degassed solutions.…”

Section: Methodsmentioning

confidence: 99%

Fast and Slow Time Regimes of Fluorescence Quenching in Conjugated Polyfluorene−Fluorenone Random Copolymers: The Role of Exciton Hopping and Dexter Transfer along the Polymer Backbone

et al. 2006

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The luminescence decay kinetics of polyfluorene copolymers containing fluorenone units randomly distributed along the polymer chain have been studied by steady-state and time-resolved fluorescence techniques in toluene solution. The typical green emission from polyfluorenes containing 9-fluorenone moieties is only observed if the 9-fluorenone group is covalently attached to the polymer. Small-angle neutron scattering (SANS) measurements indicate that, independent of the 9-fluorenone fraction, all the studied copolymers adopt an open wormlike conformation. This prevalent 1-dimensional arrangement confirms that the green emission observed with polyfluorenes is not the result of excimer formation in the typical sandwich-like conformation. Analysis of time-resolved fluorescence decays by the maximum entropy method (MEM) collected at the polyfluorene emission (415 nm) and by global analysis of decays collected at 415 and 580 nm (the 9-fluorenone defect emission wavelength) clearly indicates two different time regimes in the population of the fluorenone defect: one occurring in the time interval of 10 to 30 ps and a second one occurring in the time range from 70 to 200 ps. While the slower process shows a linear dependence with the 9-fluorenone fraction, compatible with a hopping migration process along the polymer chain, the faster process does not show such a dependence and instead suggests a short-range Dexter mechanism. These findings are in agreement with our previous work where the presence of a faster component was suggested.

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Section: Methodsmentioning

confidence: 99%

Fast and Slow Time Regimes of Fluorescence Quenching in Conjugated Polyfluorene−Fluorenone Random Copolymers: The Role of Exciton Hopping and Dexter Transfer along the Polymer Backbone

et al. 2006

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“…26 It is widely assumed that ͑⌫͒ is equal to the distribution of total rates. 21,23,24,43,44 A comparison with Eq. ͑13͒ shows that this is not true and reveals that ͑⌫͒ contains information about both the radiative and nonradiative rates:…”

Section: ͑13͒mentioning

confidence: 99%

“…However, in many cases the decay is much more complex and strongly differs from singleexponential decay. 4,15,16,[21][22][23][24][25] This usually means that the decay is characterized by a distribution of rates instead of a FIG. 1.…”

Section: Introductionmentioning

confidence: 99%

Statistical analysis of time-resolved emission from ensembles of semiconductor quantum dots: Interpretation of exponential decay models

et al. 2007

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We present a statistical analysis of time-resolved spontaneous emission decay curves from ensembles of emitters, such as semiconductor quantum dots, with the aim of interpreting ubiquitous non-single-exponential decay. Contrary to what is widely assumed, the density of excited emitters and the intensity in an emission decay curve are not proportional, but the density is a time integral of the intensity. The integral relation is crucial to correctly interpret non-single-exponential decay. We derive the proper normalization for both a discrete and a continuous distribution of rates, where every decay component is multiplied by its radiative decay rate. A central result of our paper is the derivation of the emission decay curve when both radiative and nonradiative decays are independently distributed. In this case, the well-known emission quantum efficiency can no longer be expressed by a single number, but is also distributed. We derive a practical description of non-single-exponential emission decay curves in terms of a single distribution of decay rates; the resulting distribution is identified as the distribution of total decay rates weighted with the radiative rates. We apply our analysis to recent examples of colloidal quantum dot emission in suspensions and in photonic crystals, and we find that this important class of emitters is well described by a log-normal distribution of decay rates with a narrow and a broad distribution, respectively. Finally, we briefly discuss the Kohlrausch stretched-exponential model, and find that its normalization is ill defined for emitters with a realistic quantum efficiency of less than 100%.

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“…Instead a different analysis method assumes no a priori knowledge of the fimctional form of ~(-r). Among these methods, the most successful are the maximum entropy method [21,22] and the exponential series approach. In the following, we will discuss analysis methods in which a form is assumed for the lifetime distribution and the parameters of the functional form are associated with some physical property of the membrane [23,24].…”

Section: Fluorescence Lifetime Distributionsmentioning

confidence: 99%

“…The analysis of the intensity decay using a continuous distribution of lifetimes is now quite common in the literature on membrane systems [1,2,21,[24][25][26][27][28][29][30][31][32][33][34][35][36][37]. What really matters is not so much the method for data analysis or the representation of the decay, but rather the meaning that is attributed to the parameters describing the lifetime distribution.…”

Section: The Meaning Of the Lifetime Distributionmentioning

confidence: 99%

Fluorescence lifetime distributions in membrane systems

Gratton

Parasassi

1995

J Fluoresc

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Membranes are complex biological systems that display heterogeneity at all spatial scales. At a molecular level, the heterogeneity arises from lipid and protein composition. At the cellular level, heterogeneity is due to membrane organization and large scale morphology. A quantitative evaluation of membrane heterogeneity at a microscopic level is very important for several fields of membrane studies. We have developed a method for the analysis of the decay of fluorescent membrane probes that can provide a quantity sensitive to membrane heterogeneity. This method is based on the analysis of the fluorescence decay using continuous lifetime distributions. The major challenge in the interpretation of the analysis results is in the identification, at a molecular level, of the mechanisms that influence the fluorescence decay. In this review we illustrate the principles of data analysis and we show examples of identification of the measured parameters with specific variables that affect membrane heterogeneity.

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Data analysis in frequency-domain fluorometry by the maximum entropy method — recovery of fluorescence lifetime distributions

Cited by 63 publications

References 16 publications

Fast and Slow Time Regimes of Fluorescence Quenching in Conjugated Polyfluorene−Fluorenone Random Copolymers: The Role of Exciton Hopping and Dexter Transfer along the Polymer Backbone

Fast and Slow Time Regimes of Fluorescence Quenching in Conjugated Polyfluorene−Fluorenone Random Copolymers: The Role of Exciton Hopping and Dexter Transfer along the Polymer Backbone

Statistical analysis of time-resolved emission from ensembles of semiconductor quantum dots: Interpretation of exponential decay models

Fluorescence lifetime distributions in membrane systems

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