Picosescond fluorescence lifetime standards for frequency- and time-domain fluorescence

Abstract

We characterized a series of dimethylamino-stilbene derivatives as standards for time-domain and frequency-domain lifetime measurements. The substances have reasonable quantum yields, are soluble in solvents available with a high purity, and do not show significant sensitivity to oxygen quenching. All the fluorophores displayed single exponential intensity decays, as characterized by frequency-domain measurements to 10 GHz. The decay times vary from 880 to 57 ps, depending on structure, solvent, and temperature, which is a useful range for modern picosecond time-domain or gigahertz frequency-domain instruments. These fluorophores may be used either to test an instrument or as reference compounds to eliminate color effects. We also characterized two-fluorophore mixtures, with the decay times spaced twofold (150 and 300 ps), with varying proportions. These mixtures are useful for testing the resolution of other time- and frequency-domain instrumentation. The excitation wavelength ranges from 260 to 430 nm, and the emission from 350 to 550 nm. The decay times are independent of the excitation and emission wavelengths.

Testing Fluorescence Lifetime Standards using Two-Photon Excitation and Time-Domain Instrumentation: Rhodamine B, Coumarin 6 and Lucifer Yellow

“…Since the introduction of lasers with a high repetition rate in the late 1970s[15, 23] a number of contributions have been made in determining lifetime standards[17, 18, 26], although many proposed lifetime standards were too long to benefit for picosecond instruments, and some were later found unsuitable because they exhibited double-exponential decays. Also, no systematic approach to determine the reliability of these lifetimes was done until 2007[5], when comparisons of 13 different fluorophores were systematically examined by 9 separate laboratories in a very thorough and comprehensive work.…”

Fluorescence standards: Classification, terminology, and recommendations on their selection, use, and production (IUPAC Technical Report)

“…[47] are used to calibrate or test the resolution of time-and frequency-domain instrumentation employed for luminescence lifetime measurements [1,6,7,66,[127][128][129]. For time-and frequency-domain fluorescence lifetime spectroscopy in the picosecond to lower nanosecond temporal range, they can also be valuable to determine the (wavelengthdependent) time response of the detection system at the same emission wavelength as used for the sample, thus eliminating any color shift [1,6,7].…”

“…As many samples display bi-, multi-, or nonexponential decays, it can be valuable to have standards with more complex decay behavior and known emission decay times and known relative contributions [1,127]. Suitable standards can be best produced by combining two or more dye solutions, each with a known single exponential fluorescence decay to create bi-or multiexponential decays.…”

On the Coherent Description of Diffusion‐Influenced Fluorescence Quenching Experiments

“…Several reasons can be invoked if a positive deviation is observed at high quencher concentrations: i) ground state complex formation (we refer to this as pseudo-static quenching); ii) excited state quenching without diffusion (static quenching); or iii) diffusion assisted quenching with a nonstationary stage (dynamic quenching). [6] It is very simple to distinguish the first from the other two cases: a change in the absorption or in the fluorescence spectra shapes by adding the quencher and monoexponential fluorescence decays, even at quencher concentrations that show a positive deviation in the SV plots indicate that the reaction occurs in the fluorophore electronic ground state. For charged reactants the positive deviations naturally depend on the ionic strength.…”

“…[1][2][3][4][5] Increasingly, a big number of applications (chemical sensing, biomolecular recognition) base their analysis on the conclusions previously obtained with chemical model systems. [6] These methods have been extensively used to obtain relevant parameters of elementary reactions such as electron, energy or proton transfer. Quenching itself has also been a matter of basic research in statistical mechanics leading to many competing theories, which only recently have been compared critically.…”