Comparison of fluorescent lifetime fitting techniques

Abstract

band of 1-CNC as the temperature increases. ConclusionsIntramolecular hydrogen bonding between the N-H bond and the carbonyl group in 1-COOEC as well as the intermolecular double hydrogen bonding of the N-H-N=Ctype between molecules of 1-CNC in CC14 solutions have been investigated by infrared spectroscopy.A distance of about 2.1 Á between the N-H proton and the C=0 group favors the occurrence of intramolecular hydrogen bonding in 1-COOEC. Nevertheless, the rotation of the carboethoxy group around the Car-C bond causes this compound to exist in two configurations: the free N-H and the hydrogen-bonded N-H. These two configurations manifest themselves by the two well-separated bands in the N-H stretching frequency range of the infrared spectrum. From the temperature dependence of the intensities of these bands the intramolecular association constant K = 1.33 ± 0.26 at 25 °C, the enthalpy change AH0 = -7.40 ± 0.22 kJ mol"1, and the entropy change AS°= -22.6 ± 1.4 J mol"1 K"1 have been calculated for the intramolecular hydrogen bonding in 1-COOEC.1-CNC in nonpolar solvent is undergoing hydrogen-bonding self-association. The infrared spectrum of 1-CNC in carbon tetrachloride possesses two bands which have been well characterized as N-H band of the monomer and the double N-H band of the cyclic dimer. The relative intensities of these bands change with the concentration of 1-CNC. Moreover, the intensity of the N-H (dimer) band strongly depends on the variation of the temperature. The equilibrium constant of the dimer formation of 1-CNC in CC14 at 25 °C has been obtained as 92 ± 16 mol"1 dm3 4. The enthalpy change and the entropy change for the complexation of 1-CNC in CC14 are -33.3 ± 2.8 kJ mol"1 and -74 ± 10 J mol"1 K"1, respectively. These results are in good agreement with the cyclic structure of the dimer discussed.Acknowledgment. The authors thank the Natural Sciences and Engineering Research Council of Canada and the "Ministére de 1'Education du Quebec" for financial assistance. Thanks are also due to Mr. Jean-Claude Bolduc for having taken many of the infrared spectra on the FTIR apparatus.Registry No. l-(Carboethoxy)carbazole, 56995-05-2; 1-cyanocarbazole, 83415-88-7.

Maximizing the Biochemical Resolving Power of Fluorescence Microscopy

“…The precision of these time-domain techniques as a function of instrument parameters ( e.g. , laser repetition period T , number and shape of time bins), fluorescence lifetime ( τ ) and photon count per pixel ( N ) has been thoroughly described [1], [2], [21]–[23]. Therefore, it is instructive to compare results inferred from the general properties of Fisher information relative to state-of-the-art optimization techniques.…”

Hardware implementation algorithm and error analysis of high-speed fluorescence lifetime sensing systems using center-of-mass method

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Photon-statistics in sensitized emission FRET and FLIM: a comparative theoretical analysis

“…FRET results in the reduction of the quantum yield and the fluorescence lifetime of the donor fluorophore; in the instances where the acceptor is a fluorescent molecule, FRET also causes the sensitized emission of fluorescence from the acceptor fluorophore [1]. Fluorescence lifetime imaging microscopy (FLIM) [8,9] is thus one of the methodologies that enables researcher to quantitate FRET; among the various types of FLIM techniques, time-correlated single-photon counting (TCSPC) is considered the gold standard for its high precision and accuracy [10,11]. Biological applications of FRET and FLIM are often constrained by the limited available photon-budget, i.e.…”