Phosphorescence physical properties

Since, in the main, complexes of this type are themselves derivatives of other rhodium complexes there seem to have been few investigations of their chemical reactions apart from the metathetical reactions outlined above. Apart from spectral studies there has been little interest shown in their physical properties, although it may be noted that the emission observed from [RhCl2 ((Ph2Z)2C2H4 2]Cl (Z = P, As) complexes has been attributed to metal-localized phosphorescence.1 43 The ditertiary phosphine complexes are listed in Table 81. 

Physical Properties.—Sodium is a silver-white metal, rapidly tarnished by atmospheric oxidation, the process being attended by a greenish phosphorescence.10 In thin layers by transmitted fight the... 

Although these values are extremely important quantities, there is no established, general method for measuring them on an absolute basis. Experimental difficulty arises because the species of interest is often a transient, and hence the precise values of its desired physical properties, such as (1) the T-T absorption coefficient and (2) the phosphorescence quantum yield for the specified excitation energy and the specified eigenstate, are not available for the desired spectroscopic analysis. However, some limited methods may be used with adequate caution. These methods involve either luminescence measurement or product analysis ... 

Lerman, S. (1987) Chemical and physical properties of the normal and ageing lens spectroscopic (UV, fluorescence, phosphorescence, and NMR) analyses. Am. J. Optom. Physiol Optics, 64, 11-22. 

In accordance with the above-considered supramolecular scheme of the photoprocess, additive compounds, occurring in heterogeneous struetural zones of glassy polymer matrix, aequire imequal physical properties. This faet is elearly displayed in unequal ability of aromatic compoimds to phosphoresce, if they are injected to glassy films by different methods, namely, from combined solution by volatile solvent evaporation (films 1) and by additive absorption from the vapor phase (films 2). In this connection, tests on photoexeitation of phosphoreseence of naphthalene, a-naphthol and diphenyl in CTA and PMMA films, placed to the inert gas CO2, may be the demonstrative experiment [10]. 

A remarkable property of the sulphides of the alkaline earth metals and of beryllium and zinc is their power, when certain impurities are present, to exhibit phosphorescence after exposure to bright light. The phenomenon is not due to slow oxidation and is still observable in samples which have been kept hermetically sealed for years it is obvious, therefore, that the effect is a physical one and not analogous to the phosphorescence observable with sulphur (p. 37). The nature and amount of impurity present considerably affect the phosphorescence, chlorides for example causing an increase some impurities inhibit the action.2... 

Sj - S0, the interconversion into the triplet state Tlf is also possible. The characteristic time of the phosphorescence decay of MP, on the other hand, is rather large and amounts to 10-2 s. (For a review of the physical and chemical properties of MP, see, for example, ref. 52.)... 

The changes in the physical decay properties of the phen complex which are brought about by ligand substituents are rather different (Table 9), and are inconsistent with predictions based on the spin-orbit coupling mechanism (171). The proximity of the emission bands of the substituted phen complexes to the respective free ligand phosphorescence bands, and the relatively long emission lifetimes of these complexes led Crosby et al. to propose that the emitting levels have contributions from both IL and MLCT excited states (171,172). 

We have presented the effect of various substituents on the photo-physical, electrochemical and electroluminescence properties of green emitting iridium(lll) complexes and phosphorescent organic light emitting diodes. 

However, relativistic effects have a much more profound influence on a material s properties. Thus, the existence of a spin quantum number allows for the existence of magnetism. Moreover, as shown in most standard textbooks on physical chemistry, the phenomenon of phosphorescence can only be explained through the existence of relativistic effects. Phosphorescence involves transitions between, for example, singlet and triplet states which are only possible if some spin-operating effects exist, e.g. spin-orbit couplings. Furthermore, several experimental techniques are indirectly based on exploiting relativistic effects. These include, for example, electron-spin and NMR spectroscopies. 

Stilbenes possess a number of photophysical properties, including fluorescence and phosphorescence behavior (Figure 3.1). Because of their high sensitivity, fluorescence and phosphorescence techniques are especially useftd for solving many problems of the structure and dynamics of the chemical, physical, and biological molecular system. 

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