Photoluminescence kinetics

A description is proposed for luminescence decay in Mn-doped CdS quantum dots based on a model implying radiative and dispersive n on-radiative decay of excited impurity ions. The model provides an adequate explanation of experimental photoluminescence kinetics in CdS Mn nanociystals. The excited state lifetime evaluated for Mn ions is about 2.3 ms and close to the bulk case. 

Figure 2. Photoluminescence kinetics of quantum size CdS Mn nanocrystals at various wavelengths.

Figure 3. Fitting of Mn photoluminescence kinetics data by the modified stretched exponential function.

Agekyan VF, Stepanov YA, Emtsev VV, Lebedev AA, Poloskin DS, Remenjmk AD (1999) Effect of y irradiation on the photoluminescence kinetics of porous silicon. Semiconductors 33 1315-1317 Aouida S, Saadoun M, Ben Saad K, Bessais B (2006) UV photooxidation induced structural and photoluminescence behaviors in vapor-etching based porous silicon. Mater Sci Eng C 26 495 99... 

In photoluminescence one measures physical and chemical properties of materials by using photons to induce excited electronic states in the material system and analyzing the optical emission as these states relax. Typically, light is directed onto the sample for excitation, and the emitted luminescence is collected by a lens and passed through an optical spectrometer onto a photodetector. The spectral distribution and time dependence of the emission are related to electronic transition probabilities within the sample, and can be used to provide qualitative and, sometimes, quantitative information about chemical composition, structure (bonding, disorder, interfaces, quantum wells), impurities, kinetic processes, and energy transfer. 

V.V. Antonov-Romanovskii, Kinetics of Photoluminescence of Crystal Phosphors (Nauka, Moscow, 1966). 

Figure 10. Transient photoluminescence of opalCT (a) and opal A (b) and kinetics at maximum...

Studies on luminescence of CdS colloids provide useful knowledge on the energy and nature of recombination sites of charge carriers in the colloidal particles. The regularities of the colloid photoluminescence quenching provide the information on the dynamics of electrons and holes in semiconductor particles as well as on the kinetics of interfacial electron transfer. Of a particular interest are studies on the luminescence of colloidal solutions of the so-called Q-semiconductors, their properties depending on the size of semiconductor particles due to the quantum size effects. 

The determination of the photoluminescence parameters (excitation frequency, emission frequency, Stokes shift, fine structure parameter, and lifetime) can lead to information which, at the simplest level, indicates the presence of an electronically excited state of a species, but which can be sufficiently detailed so as to lead to a clear identification and characterization of the photoluminescent sites(J6-44). Moreover, measurements of the variations in the intensity and positions of the bands as a function of time (time-resolved photoluminescence) provide valuable kinetic data representing the reactions occurring at the surface. Although most of the photoluminescence measurements have been carried out at low temperatures for specific reasons (see Section III.C.2), there is much evidence that some of the excited states involved are present even at higher temperatures and that they play an important role in catalytic and photocatalytic reactions. Therefore, it is clear that the information obtained by photoluminescence techniques is useful and important lor the design of new catalysts and photocatalysts. 

Neutral organoarsenic compounds of the type R3ASO are widely used for extraction of uranium and other valuable elements from aqueous solutions The photoluminescence method has been applied to study the kinetics of formation of complexes of uranyl cations with organic and inorganic ligands ... 

Time-resolved fluorescence studies of fluorene-fluorenone copolymers in dilute toluene solution, enable us to identify different time regimes in the photoluminescence (PL) decay. Figure 18 shows the results of a maximum entropy method (MEM) analysis of the PL decays of fluorene-fluorenone copolymers [58] collected at the fluorene emission wavelength [66]. The different time regimes of the PL decay are associated with different kinetic species which migrate to the defects, most typically these are the CTS defects... 

Antonov-Romanovsky, V. V. Kinetics of Crystalophosphors Photoluminescence, Moscow, Nauka, 1966... 

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