Ultraviolet light radiation

Automatic fire detectors are designed to sense the presence of a fire. They accompUsh this by detecting one of the elements of a fire heat, infrared or ultraviolet light radiation, and particulate aerosols, which are found in smoke. However, not all fires produce all of these elements, and some conditions that are unrelated to fires may produce certain of these effects. Therefore an effective fire detector must be able to differentiate between a fire condition and an ambient background level of these elements. Several types of detectors have been developed to sense fire elements. Some devices are single-function detectors while others may be designed to sense more than one element. 

Toroti, M., Olayemi, J.Y., Adeniyi, J.B., Peters, O. The photooxidative degradation of poly (vinylchloride)—2. The stabiUsing action of dibutyltin maleate and tris-nitro (1,3-dihydroxyl-2-hydroxymethyl-2-nitropropane) on PVC from ultraviolet light radiation. 

Optically stimulated electron emission (OSEE) (cleaning) Electron emission from a metal surface under ultraviolet light radiation. Changes in OSEE can be used to quanhfy surface contamination. 

Another phenomenon that was inexplicable in classical terms was the photoelectric effect discovered by Hertz in f 887. When ultraviolet light falls on an alkali metal surface, electrons are ejected from the surface only when the frequency of the radiation reaches the threshold... 

Another factor in oxidative degradation is ultraviolet radiation, of which sunlight is a rich source. The oxidation of parylene appears to be enhanced by ultraviolet radiation. 02one may play a mechanistic role in the ambient temperature exposure of parylenes to ultraviolet radiation in the presence of oxygen. For the best physical endurance, exposure of the parylenes to ultraviolet light must be minimised. 

Scintillation detectors are substances which fluoresce when stmck by x-radiation. Scintillation can, therefore, serve to convert x-ray photons into visible or ultraviolet light. Scintillation materials include thaUium-activatedcrystals of sodium iodide, NaI(Tl), potassium iodide, KI(T1), or cesium iodide, CsI(Tl) crystals of stilbene (a, P-diphenylethylene) [588-59-0] and anthracene [120-12-7] bismuth germanium oxide [12233-56-6] ... 

Ultraviolet radiation causes cleavage of the aryl ether linkage (23). DMPPO undergoes oxidation when exposed to ultraviolet light and oxygen by direct attack on the aromatic ring to produce a variety of ring-cleaved and quinoidal stmctures (24). 

Ultraviolet light sources are based on the mercury vapor arc. The mercury is enclosed ia a quart2 tube and a potential is appHed to electrodes at either end of the tube. The electrodes can be of iron, tungsten, or other metals and the pressure ia a mercury vapor lamp may range from less than 0.1 to >1 MPa (<1 to >10 atm). As the mercury pressure and lamp operating temperatures are iacreased, the radiation becomes more iatense and the width of the emission lines iacreases (17). 

Addition to Olefins. OrganohydrosHanes can also be prepared by addition of halosHanes and organosilanes containing multiple Si—H bonds to olefins. These reactions are catalyzed by platinum, platinum salts, peroxides, ultraviolet light, or ionizing radiation. 

Nitro-substituted indolino spiroben2opyrans or indolino spironaphthopyrans are photochromic when dissolved in organic solvents or polymer matrices (27). Absorption of uv radiation results in the colorless spiro compound [1498-88-0], C22H2gN202, being transformed into the colored, ring-opened species. This colored species is often called a photomerocyanine because of its stmctural similarity to the merocyanine dyes (see Cyanine dyes). Removal of the ultraviolet light source results in thermal reversion to the spiro compound. 

Light and Toxic Reactions In many individuals, exposure to ultraviolet radiation from the sun causes skin reactions such as erythema, thickening of the epidermis, and darkening of existing pigment. Exposure to ultraviolet light also increases the risk of different forms of skin cancers, especially malignant melanoma. ... 

We have limited our investigations to the action of gamma-rays and fast neutrons on aromatic, alicyclic, aliphatic, and ionic compounds. The absorption coefficients for these types of radiation have an order of magnitude of lO /cm which is particularly adequate. Shallow penetrating radiations would only alter the superficial layers and would obviously not be able to affect the intensity of the quadrupole line substantially. This is for instance the case for ultraviolet light which has been shown to be unable to produce any effect on the resonance line of iodoform (CHI3 3Sg)... 

It is advisable to wrap the entire apparatus with aluminum foil to avoid exposure to ultraviolet light. The reaction solution can be observed through a small hole in the aluminum foil which is shielded from the direct radiation of the lamp. 

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