UV-emitters

III—V nitride compounds suitable for fabricating blue/uv emitters. Also shown is the lattice parameter of various materials proposed as substrates. 

It is ironic to consider the III-V nitrides, the premier materials for short wavelength blue and UV emitters, as sources of infrared light. However, Er-doped GaN is of interest for making electrically pumped, temperature insensitive, broad band and compact optical amplifiers or sources of 1.54 pm light. Applications include long-haul communication systems (amplifiers), local area networks (50/50 splitters) and sources (lasers) for transmission in silica-based optical fibres. 

One unusual application is a UV emitter containing Eu + SrB407 insects can see the UV and be attracted to it, so it has been used in insect traps. 

Group II-VI Materials are presently important for optoelectronics in two device applications at opposite spectral regions, as well as in photovoltaics. The two device applications are the blue and near UV emitters (ZnS, ZnSe) and the near to far IR detectors (HgCdTe). 

The gold compounds (12.403) represent the many P compounds reported to have luminescent properties [37]. Compounds of types BaHfi Zr (P04)2 and K2Hfi r (P04)2 are UV emitters under x-ray excitation and this will lead to sharper radiographic images (Table 12.63) [38]. 

Another intensively studied area of research with numerous contributions from Japan is the use of polysilanes as UV emitters in OLEDs. In polysilane based UV OLEDs with a layered design, the polysilane acts as semiconducting and emitting layer. The first UV OLED using polymethylphenylsilane was published in 1995 [119] but electroluminescence was only detectable at very low temperatures (77 K). Luminescence was drastically reduced at higher temperatures, the reason for this being a thermally induced conformational change of the silicon... 

To apply nonpolar nitrides to devices such as high-electron-mobility transistors and UV emitters/detectors, AlGaN is an essential material. However, when AlGaN is grown on GaN, cracks are generated by tensile stress when the layer... 

J Edmond, H Kong, V Dmitrieve. Blue/uv emitters from SiC and its aUoys. Inst Phys Conf Ser 137 ... 

Darmawan N, Yang C-H, Mauro M, et al. Efficient near-UV emitters based on cationic bis-pincer iridinm(III) carbene complexes. Inorg Chem. 2013 52 10756-10765. 

Scintillation counters, which constitute an extremely important group, depend upon the absorption of radiation by a scintillator to produce UV light scintillations, which are detected and converted into amplified voltage pulses by a photomultiplier (Figure 10.10). Solid scintillators are used extensively for the detection and analysis ofy-rays and X-rays, while liquid scintillators find widespread employment in the measurement of pure negatron emitters, especially where the particle energy is low (< 1 MeV). 

PAHs adsorbed on particles of carbon black were also photostabilized (Behymer and Hites, 1988). However, Barofsky and Baum (1976) demonstrated that BaP, anthracene, BaA, and pyrene deposited on carbon microneedle field desorption emitters and exposed to UV radiation were all photooxidized to carbonyl compounds. Similarly, PAHs can photodegrade efficiently in air when adsorbed to substrates of silica gel, alumina, or glass plates (e.g., see Lane and Katz, 1977 Kormacher et al., 1980 Behymer and Hites, 1985 Yokely et al., 1986). 

The emitting species for sulfur compounds is excited S2. The lambda maximum for emission of excited S2 is approximately 394 nm. The emitter for phosphorus compounds in the flame is excited HPO with a lambda maximum equal to doublet 510-526 nm. In order to detect one or the other family of compounds selectively as it elutes from the GC column, the suitable band-pass filter should be placed between the flame and the photomultiplier tube to isolate the appropriate emission band. In addition, a thermal infrared filter is mounted between the flame and the photomultiplier tube to isolate only the visible and UV radiation emitted by the flame. Without this filter, the large amounts of infrared radiation emitted by the combustion reaction of the flame would heat up the photomultiplier tube, thus increasing its background signal. 

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