Molecular radiative transport. III. Experimental intensity decays

Abstract

A critical experimental test of a previously developed theory of molecular radiative transport is described. It is concluded that the theory gives an accurate description of the effect of radiative transport on fluorescence observables. The numerical coefficients of the fluorescence decay are computed from a Monte Carlo integration procedure that mimics the photon trajectories inside a realistic sample cell, and is carried out only using known molecular and geometrical parameters. The predicted parameters are confronted with the experimental observables accessible in a typical single-photon timing experiment, rhodamine 101 in ethanol being the system studied. The theoretical predictions quantitatively describe the effects of concentration and excitation and emission wavelengths experimentally observed in optical dense nondiffusing media for the two most common geometric arrangements: front-face and right-angle detection. It is shown that radiative transport leads to spatially heterogeneous fluorescence kinetics, as a direct consequence of the existence of a spatial distribution function of electronic excitation inside the sample cell. The agreement between theory and experimental results is good, with the average decay times predicted within ≃3% accuracy for front-face detection.

Standards for Photoluminescence Quantum Yield Measurements in Solution

“…A later report from Drexhage's group gives Φ f = 0.96 [30]. Pereira et al reported that the QY of rhodamine 101 is equal to that of rhodamine 6G (Table 1) [35]. Very recent work from Würth et al finds Φ f = 0.90 [36].…”

“…In order to make sure that the carboxylic acid group is protonated, most (but not all) authors add some acid to the solvent. The large overlap of absorption and emission spectra of rhodamine 101 can lead to complications owing to reabsorption of emitted light [35]. • SulfoRhodamine 101 was included in a careful comparative study by Velapoldi and Tønnesen [13], but also in this case, independent verification is desirable.…”

Photodynamics of a PV Trimer in High‐Viscosity Solvents and in PMMA Films: A New Insight into Energy Transfer versus Conformational Relaxation in Conjugated Polymers

“…[28][29][30] The analysis of this problem is rather complex and will not be attempted in detail here.…”

Accurate Determination of the Limiting Anisotropy of Rhodamine 101. Implications for Its Use as a Fluorescence Polarization Standard

“…1,2,7 In room temperature acidified ethanol, where the dye is present in the cationic form, it has a fluorescence quantum yield of about 0.9 6 and a single exponential fluorescence decay with a lifetime of 4.3 ns. 6 The cation and the zwitterion share a common fluorophore, whereas the lactone form has quite different photophysical properties. 8 A precise determination of the S 1 -S 0 limiting anisotropy (i.e., the highest measured S 1 -S 0 anisotropy for a given molecule) of several xanthene dyes, including the rhodamines B, 6G and 101, and fluorescein, r 0 ) 0.373 ( 0.002, was reported by Johansson,9 on the basis of both steady-state and time-resolved measurements.…”