Fluorescence, first observation

Sekatskii S K and Ketokhov V S 1996 Single fluorescence centres on the tips of crystal needles first observation and prospects for application in scanning one-atom fluorescence microscopy Appl. Phys. B 63 525-30... 

The first observations on the fluorescence of colloidal CdS were made using a colloid stabilized by colloidal silicon dioxide . The fluorescence spectrum consisted of a broad band with the maximum between 580 nm and 650 nm. The reproducibility of this red fluorescence was very poor. In the presence of excess Cd ions the intensity of the fluorescence was increased, which indicates that anion vacancies were centers of luminescence. Aging of the sol for a few weeks in the dark and in the absence of air was accompanied by an increase in fluorescence intensity by a factor of ten and a gradual red shift of the fluorescence band. However, even after this increase, the fluorescence quantum yield was still below 10 . ... 

The first observations of P-type delayed fluorescence arose from the photoluminescence of organic vapors.<15) It was reported that phenanthrene, anthracene, perylene, and pyrene vapors all exhibited two-component emission spectra. One of these was found to have a short lifetime characteristic of prompt fluorescence while the other was much longer lived. For phenanthrene it was observed that the ratio of the intensity of the longer lived emission to that of the total emission increased with increasing phenanthrene vapor... 

P-type delayed fluorescence is so called because it was first observed in pyrene. The fluorescence emission from a number of aromatic hydrocarbons shows two components with identical emission spectra. One component decays at the rate of normal fluorescence and the other has a lifetime approximately half that of phosphorescence. The implication of triplet species in the mechanism is given by the fact that the delayed emission can be induced by triplet sensitisers. The accepted mechanism is ... 

E-type delayed fluorescence is so called because it was first observed in eosin. 

F. Perrin First observation of alpha phosphorescence (E-type delayed fluorescence)... 

When D and A are identical (3D + 3D —> 3D + 3D ), triplet-triplet annihilation leads to a delayed fluorescence, called P-type delayed fluorescence because it was first observed with pyrene. Part of the energy resulting from annihilation allows one of the two partners to return to the singlet state from which fluorescence is... 

Finally, if the solvent reorganization time is of the order of the excited-state lifetime, the first emitted photons will correspond to wavelengths shorter than those emitting at longer times. In this case, the fluorescence spectrum observed under continuous illumination will be shifted but the position of the maximum cannot be directly related to the solvent polarity. 

The characteristic transient yellow-green fluorescence exhibited by adrenaline solutions that were undergoing oxidation in the presence of alkali was first reported in 1918.182 This phenomenon was later shown to be general, and similar (but usually weaker) fluorescences were observed when other catecholamines were oxidized in alkaline solution.133 Many years were to elapse before the correct explanation of this phenomenon was forthcoming, i.e. that the fluorescent product derived from adrenaline was a rearrangement product of adrenochrome (the red oxidation product of adrenaline). 

B) P-type delayed fluorescence is so called because it was first observed in pyrene and phenanthrene solutions. In aromatic hydrocarbons singlet-triplet splitting is large and therefore thermal activation to excited singlet state at room temperature is not possible. The mechanism was first formulated by Parker and Hatchard based on the observation that the intensity of emission of the delayed fluorescence Ipd was proportional to the square of the intensity of absorption of the exciting light Ia. 

In some cases, simultaneously with the quenching of the normal fluorescence a new structureless emission band appeals at about 6000 cm-1 to the red side of the monomer fluorescence spectrum (Figure 6.4). This phenomenon was first observed in pyrene solution by Forster and was explained as due to transitory complex formation between the ground and the excited state molecules since the absorption spectrum was not modified by increase in concentration. Furthermore, cryoscopic experiments gave negative results for the presence of ground state dimers. These shortlived excited state dimers are called pxcimers to differentiate them from... 

In most of the europium complexes the fluorescence is due to the last effect. The intramolecular energy transfer within europium and terbium complexes was first observed by Weissman [630] in 1942, and subsequently investigated by many other workers. 

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