Non-radiative properties

Extensive research including the study of radiative and non-radiative properties of rare-earth ions has been carried out. Especially, the Judd-Ofelt theory has been applied to most rare-earth — fluoride-glass combinations. Typical Judd-Ofelt parameters are reported in Table 3 for ZBLAN glass [31-34], An exhaustive list of such parameters for glasses and crystals can be found in Ref. [35]. 

Although this good fit is certainly fortuitous due to the many approximations behind it, it shows that the non-radiative properties behave as expected. However, when pumping is increased to 1 GW cm level, a threshold is reached where a strong, narrowed and shortened emission at 1.054 ftm is observed (fig. 13). This points to the existence of some feedback, probably provided by total reflection at grain boundary some partial laser action then takes place (see sect. 2.2.3.). 

A or Q, acts as the electron donor. The radiative and non-radiative properties of exciplexes are very sensitive to solvent polarity. In sufficiently polar solvents, dissociation to free ions is the major pathway of exciplex deactivation. 

Touloukian, Y.S., and DeWitt, D.P. (1972), Thermal Radiative Properties of Non-metallic Solids, in Thermophysical Properties of Matter, Plenum, New York, pp. 3a-48a. 

S. Link and M. A. El-Sayed, Shape and size dependence of radiative, non-radiative and photothermal properties of gold nanocrystals. Int. Rev. Phy. Chem. 19(3), 409-453 (2000). 

As briefly mentioned in the previous section, PCS provides quantitative information on the lifetime of the non-radiative state for molecules in solution in the time range from sub-microseconds to seconds. This method can, potentially, be applied to the characterization of the photophysical properties of quantum dots freely diffusing in solution with higher temporal resolution than the previous SPD. 

Molecular rotors are fluorophores characteristic for having a fluorescent quantum yield that strongly depends on the viscosity of the solvent [50], This property relies on the ability to resume a twisted conformation in the excited state (twisted intramolecular charge transfer or TICT state) that has a lower energy than the planar conformation. The de-excitation from the twisted conformation happens via a non-radiative pathway. Since the formation of the TICT state is favored in viscous solvents or at low temperature, the probability of fluorescence emission is reduced under those conditions [51]. Molecular rotors have been used as viscosity and flow sensors for biological applications [52], Modifications on their structure have introduced new reactivity that might increase the diversity of their use in the future [53] (see Fig. 6.7). 

This paper is organized as follows. Section 2 presents non-trivial properties of the velocity distribution functions for RIG for quasi and ordinary particles in one dimensions. In section 3 we find the state equation for relativistic ideal gas of both types. Section 4 presents the distribution function for the observed frequency radiation generated for quasi and ordinary particles of the relativistic ideal gas, for fluxons under transfer radiation and radiative atoms of the relativistic ideal gas. Section 5 presents a generalization of the theory of the relativistic ideal gas in three dimensions and the distribution function for particles... 

The interaction of semiconductor with nanocarbon induces a modification of the intrinsic properties of semiconductor particles (band gap, charge carrier density, lifetime of charge separation, non-radiative paths, etc.) [1] as well as of the surface properties which were discussed in detail in the previous section. 

Here, is the rate constant for radiative decay (fluorescence), while k r is the combined rate constant for aU non-radiative decay processes, is virtually constant and is an inherent property of the material in question, and for this material is significantly greater than k r, given the high fluorescence efficiency. When a fluorescence quencher, such as TNT, is introduced, km increases because an additional efficient non-radiative pathway now exists. This, via Eq. (4), makes r smaller. 

In the sections which follow, the principles discussed above will be used in exploring the properties of a range of platinum(II) complexes. The emphasis of the chapter will be on emission—luminescence—from Pt(II) complexes, on the features and properties of molecules that tend to favor emission over other non-radiative processes. In other words, photophysics, as opposed to photochemistry, is our main subject here, but we also consider other excited state processes in selected systems, such as electron transfer and photooxidation. 

In this Chapter we describe the extension of the parametric model used for 4f" spectra to calculations of absorption and emission spectra for the 4f 15d configuration. We also illustrate how they can be applied to calculate other properties of interest, such as non-radiative relaxation rates. Finally, we discuss the relationship between parametrized calculations and other approaches, such as ab initio calculations. 

Once the parameters are determined, we can calculate other spectroscopic properties for the 4f 15d configuration. These include emission spectra and lifetimes, the presence (or lack of) emission from the 4f 15d configuration, and non-radiative relaxation effects upon the linewidths of 4f 15d and 4F excited states. 

Duan et al. (2007) present an alternative approach to these ab initio calculations. They suggest that, rather than attempting to calculate the multitude of 5d energy levels directly, ab initio approaches could concentrate on producing useful parameter values for only the subset of terms in the parametrized Hamiltonian (see section 2) which cannot be experimentally determined. That is, the ab initio calculations could produce reliable values, for example, for the / (fd) and <7v(fd) parameters that could then be incorporated into parametrized calculations. The parameters may then be fine tuned to give a reliable calculation that might be used to investigate other properties of the ions, such as the non-radiative relaxation discussed in section 3.4. 

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