Luminescent phenomena

Fig. 5 Schematic representation of the electronic transitions during luminescence phenomena [5]. — A absorbed energy, F fluorescence emission, P phosphorescence, S ground state. S excited singlet state, T forbidden triplet transition.

The Early Period. Luminescent phenomena such as the aurora borealis, phosphorescence of the sea, luminous animals and insects, and phosphorescent wood were the earliest of spectral observations because th require nothing more than the... 

It has been known for centuries that many compounds emit visible radiation when they are exposed to sunlight. Luminescence phenomena, such as the aurora borealis, phosphorescence of the sea, luminous animals and insects, phosphorescent wood, etc., have fascinated man since antiquity, being reflected in the early scientific literature. Aristotle (384-322 b.c.) appears to be one of the first philosophers to recognize cold light in dead fish, fungi, and the luminous secretion of the cuttlefish [1],... 

These luminescence phenomena have been known since ancient times according to the legend, about 1000 b.c., a Chinese emperor possessed a magic paint on which the image of an ox appeared at sunset. The chemical composition of the paint used was not known. This is the first known case of a man-made substance capable of storing daylight for later recovery [2],... 

Although numerous materials and fluorescing solutions were described in the seventeenth and eighteenth centuries, and in spite of the fact that since around 1860 mineralogists started the use of fluorescence for detection of mineral deposits, little progress was observed concerning the explanation of the phenomenon, and it was only around the mid-nineteenth century that important achievements were made in the study and understanding of luminescence phenomena. 

In 1935, after studying the luminescence of various colorants, Jablonski suggested the electronic energy diagram of the singlet and triplet states to explain the luminescence processes of excitation and emission. The proposed diagram of molecular electronic energy levels formed the basis of the theoretical interpretation of all luminescent phenomena [21],... 

The term chemiluminescence was not introduced until 1888, when Wiedemann defined the term luminescence. He was able to classify luminescence phenomena of six different kinds, according to the manner of excitation photoluminescence, caused by the absorption of light, electroluminescence, produced in... 

Table 1 Classification of Luminescence Phenomena Produced from irradiation...

When this emission originates from living organisms or from chemical systems derived from them, it is named bioluminescence (BL). Both phenomena are luminescence processes that have been traditionally distinguished from related emissions by a prefix that identifies the energy source responsible for the initiation of emission of electromagnetic radiation. Based on Wiedemann s classification, which was discussed in Chapter 1, contemporary luminescence processes have been added to the list of luminescence phenomena, as can be seen in Table 1. 

For a more detailed discussion of many of these luminescent phenomena, especially the theory of how they arise, the reader should consult the treatise by Blasse and Grabmaier and by Vij. ... 

Above 250°C. we approach, in the gas phase, what is known as the cool flame regime. This is characterized by induction periods and by the appearance of pressure peaks and luminescent phenomena in the oxygen-hydrocarbon system. The consensus of present data seems to support the contention that these cool flames arise from the secondary decomposition of the hydroperoxides produced by the low temperature chain. The unimolecular decomposition of the hydroperoxide yields active alkoxy and hydroxyl radicals ... 

One more type of luminescence phenomena associated with electron tunneling was suggested in ref. 72. In the scheme of Fig. 17, this transition is denoted by b. 

Furthermore, the upconverted luminescence phenomena of Er and Sm " have been observed in YVO4 film. Fig. 5(b) shows the upconverted emission spectrum of Er excited with 800nm and that of Sm excited with 940nm. The characteristic green... 

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