Flash sources

All these characteristics allow to measure FAD with a statistic quality and a reliability out of reach of flash sources. Moreover, in the case of polymers, it is generally not possible to purify samples as much as one would wish to perform a fluorescence experiment in comfortable conditions, and the free choice of wavelength permitted by the continuous spectrum of the synchrotron source is essential. In this regard, lasers, which also provide very intense and short light pulses usable for fluorescence experiments somewhat less flexible. This may partly explain... 

Photochemical Dissociation.—This method has many advantages the system is relatively simple and well understood, a wide range of conditions may be used and almost all radicals can be produced photochemically. With ordinary light sources, however, the concentration of radicals which can be obtained is so low that it has been impossible to detect them by means of their absorption spectra. The use of high intensity flash sources has completely overcome this difficulty and partial pressures of atoms and radicals of the order of cm. Hg have been produced, malang this the most powerful of all methods of preparation. ... 

PMMA) was employed. In addition, atomic force microscopy is used for a more quantitative read-out of the PMMA. Since it is a two-step process - an image formation step on the photoresist followed by a magnification of the miniature contact print formed on the resist - it is difficult to use in the study of dynamic processes. The use of flash sources such as X-ray lasers or laser-produced plasmas in addition to the use of synchrotron radiation sources increased the activity of X-ray contact imaging, allowing the capture of the image on a nanosecond time scale. 

The arc flash protection boundary is the distance from an arc flash source within which an unprotected person has a 50 percent chance of receiving injuries greater than a second degree bum shouid an arc flash occur. To remove operators from this boundary and decrease their chance of being harmed,... 

Bossu R, Gilles S, Mazet-Roux G, Roussel F, Kamb L (2011) Flash sourcing, or rapid detection and characterization of earthquake effects through website traffic analysis. Ann Geophys 54(6) 716-727... 

One of the most important teclmiques for the study of gas-phase reactions is flash photolysis [8, ]. A reaction is initiated by absorption of an intense light pulse, originally generated from flash lamps (duration a=lp.s). Nowadays these have frequently been replaced by pulsed laser sources, with the shortest pulses of the order of a few femtoseconds [22, 64]. 

The chief danger and main source of error in a combustion is that of moving the Bunsen forward a little too rapidly and so causing much of the substance to burn very rapidly, so that a flash-back occurs. This usually causes an explosion wave to travel back along the tube towards the purification train, some carbon dioxide and water vapour being carried with it. If these reach the packing of the purification train they will, of course, be absorbed there and the results of the estimation will necessarily be low. 

Flash points and autoignition temperatures are given in Table 11. The vapor can travel along the ground to an ignition source. In the event of fire, foam, carbon dioxide, and dry chemical are preferred extinguishers. The lower and upper explosion limits are 1% and 7%. 

Acetone can be handled safely if common sense precautions are taken. It should be used in a weU-ventilated area, and because of its low flash point, ignition sources should be absent. Flame will travel from an ignition source along vapor flows on floors or bench tops to the point of use. Sinks should be rinsed with water while acetone is being used to clean glassware, to prevent the accumulation of vapors. If prolonged or repeated skin contact with acetone could occur, impermeable protective equipment such as gloves and aprons should be worn. 

Flammability Acrolein is very flammable its flash point is <0° C, but a toxic vapor cloud will develop before a flammable one. The flammable limits in air are 2.8% and 31.0% lower and upper explosive limits, respectively by volume. Acrolein is only partly soluble in water and will cause a floating fire, so alcohol type foam should be used in firefighting. The vapors are heavier than air and can travel along the ground and flash back from an ignition source. 

The relatively low flash points of some acrylates create a fire hazard. Also, the ease of polymerization must be home in mind in ah. operations. The lower and upper explosive limits for methyl acrylate are 2.8 and 25 vol %, respectively. Corresponding limits for ethyl acrylate are 1.8 vol % and saturation, respectively. All possible sources of ignition of monomers must be eliininated. 

Acrylonitrile is combustible and ignites readily, producing toxic combustion products such as hydrogen cyanide, nitrogen oxides, and carbon monoxide. It forms explosive mixtures with air and must be handled in weU-ventilated areas and kept away from any source of ignition, since the vapor can spread to distant ignition sources and flash back. 

---