How is the fluorescence lifetime of a sample measured?
Fluorescence lifetime can be measured in either the frequency domain or the time domain. The time domain method involves the illumination of a sample (a cuvette, cells, or tissue) with a short pulse of light, followed by measuring the emission intensity against time.
How is lifetime for decay calculated?
Calculate the value of the decay constant λ. = = , where 1/λ = τ = mean lifetime. By measuring (ΔN/N)/Δt = λ several times for a random collection of one type of particle, one can determine an average value for λ and, consequently, an average value for τ, the mean lifetime of the particle.
How do you measure fluorescence polarization?
Fluorescence polarization is then measured as the difference of the emission light intensity parallel (I||) and perpendicular (I⊥) to the excitation light plane normalized by the total fluorescence emission intensity.
What is fluorescence anisotropy used for?
Fluorescence anisotropy can be used to measure the binding constants and kinetics of reactions that cause a change in the rotational time of the molecules. If the fluorophore is a small molecule, the rate at which it tumbles can decrease significantly when it is bound to a large protein.
What is self-quenching fluorescence?
Self-quenching is a special type of fluorescence quenching in which fluorophore and quencher molecules are the same. Fluorescence self-quenching is particularly evident in highly concentrated solutions of fluorophores at right-angle geometry [15], [18], [19].
What is a decay lifetime?
Decay Rate The half-life (t1/2) is the time taken for the activity of a given amount of a radioactive substance to decay to half of its initial value. The mean lifetime (τ, “tau”) is the average lifetime of a radioactive particle before decay. The decay constant (λ, “lambda”) is the inverse of the mean lifetime.
How do you calculate mean lifetime?
It turns out that the mean life equals the half life divided by the natural logarithm of 2 (about 0.693). The mean life also turns out to exactly equal the number τ that appears in the exponential term e−t/τ involved with describing decay or growth, called the time constant.
What does r6g stand for?
Rhodamine 6G (R6G), also known as Rhodamine 590, is one of the most frequently used dyes for application in dye lasers and as a fluorescence tracer, e.g., in the area of environmental hydraulics. Knowing the spectroscopic characteristics of the optical emission is key to obtaining high conversion ef …
What is r6g used for lasing?
Rhodamine 6G (R6G), also known as Rhodamine 590, is widely used as a lasing medium and as a fluorescence tracer [7]. The chemical structure of the R6G molecule is illustrated in Fig. 1. For use in dye lasers, it is dissolved in methanol, ethanol and a variety of other organic solvents.
How does dye concentration affect the tunability of aqueous r6g solutions?
Concentration effects in aqueous R6G solutions are studied over the full concentration range from the solubility limit to highly dilute states. Changing the dye concentration provides tunability between ∼550 nm in the dilute case and ∼620 nm at high concentration, at which point the fluorescence spectrum indicates the formation of R6G aggregates.
What is the solubility of r6g in water?
The solubility limit of R6G in water is in the order of 0.02 g/ml; hence we cover the full range of practical interest. For each measurement, the dye solution was filled into a quartz glass cuvette and illuminated by the laser close to the glass wall.