Intrinsic radiative lifetime

Dispersion of the radiative rate constant by local variations of the refractive index at the solid/gas interface. This could explain the tailing of the decay curves even at very low loadings, with lifetime components that are two to three times as long as the intrinsic radiative lifetimes in solution/85 This could also explain the disappearance... 

The complex ion, cw-dichlorobis-4,7-dimethyl-l,10-phenanthroline iridium (III) chloride [IrCl2(4,7-mephen)2]Cl, has luminescence properties which are intermediate between the aforementioned homo-bischelated complexes (23). The emitting levels of this complex are best classified as nearly equal admixtures of cItt and tttt configurations. The luminescence lifetime at 77 °K ranges from 208 to 22 fisec as the solvent polarity is decreased. The quantum yield of 0.62 in ethanol-methanol glass at 77°K indicates an intrinsic radiative lifetime of 35 /msec under these conditions. The number of equilibrated levels responsible for the emission of this complex as in the previous case, has not been determined. 

Intrinsic radiative lifetimes. For 02(lAg) in air at atmospheric pressure this is reduced to... 

The intrinsic radiative lifetime ( . e. the lifetime if no radiationless pathways of de-excitation exist) of a process is given by... 

Intrinsic quantum yields (0[ ) estimated from a radiative lifetime to(Nd) = 0.8 ms. intrinsic quantum yields (Q j ) estimated from a radiative lifetime tq (Nd) = 0.27 ms. 

Intrinsic quantum yields (Oj ) estimated from a radiative lifetime Tq(Er) = 8 ms. 

The attachment point of the antenna is indicated by — in case of ternary complexes, the sketched molecule acts both as the ternary ligand and antenna. Intrinsic quantum yields estimated from a radiative lifetime ro(Yb) = 2 ms. 

Just as with quantum yields, there are basically two different kinds of lifetimes, one a result of direct experimental measurement, and the other a derived quantity. These have not always been carefully distinguished. Moreover, the same quantity has been labeled by a variety of names and symbols. For example, radiative lifetime, true radiative lifetime, natural lifetime, intrinsic lifetime, and inherent lifetime all mean the same thing the lifetime a molecule in an excited state would have if there were no steps competing with that of spontaneous emission of radiation. 

In about 2000, my laboratory started to study the interactions of fluorophores with metallic nanoparticles, both solution-based and surface-immobilized. Our findings agreed with other workers whom had observed increases in fluorescence emission coupled with a decrease in the fluorophores radiative lifetime. Subsequently, we applied classical far-field fluorescence descriptions to these experimental observations, which ultimately suggested a modification in the fluorophores s intrinsic radiative decay rate, a rate thought to be mostly unchanged and only weakly dependent on external environmental factors. This simple description, coupled with what seemed like a limitless amount of applications led to a paper published by our laboratory in 2001 entitled Metal-Enhanced Fluorescence , or MEF, a term now widely used today almost a decade later. 

The latter effect can be explained by taking into account that a partially polymerized diacetylene crystal is a molecular crystal containing dopant molecules with lower lying optical transition acting as traps for monomer excitations . Take k as the rate constant for non-radiative energy transfer from a donor to a trap, Tq as the intrinsic donor lifetime, and c, as the relative trap concentration, then the lifetime of a donor in presence of traps would be T = -I- k cj Since the probability that an excited... 

This enhancement of intersystem crossing by combining heavy atom and paramagnetic effects explains the relative insensitivity of the Gd phosphorescence lifetime (Table IV) to any additional heavy atom effect (as in the chelate with iodo-BTFA), or to deuteration of solvent or ligand which, by inhibiting nonradiative deactivation, usually increases the lifetime of organic phosphorescence. This insensitivity of the lifetime of the Gd chelate permits us to assign the value of ca. 3 X sec." as the intrinsic radiative rate for the triplet state for Gd BTFA chelates, and a similar value should apply for the Eu compounds. 

In this approach, the excited-state lifetime of molecules is measured by following the decay of their fluorescence. The electron injection rate ( j) is calculated from the measured fluorescence decay rate (kobs) and the intrinsic radiative (kf) and non-radiative (A nr) excited decay rates through the relationship... 

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