Luminous

The release of chemical energy during combustion of gases produces a luminous, radiating zone which is seen as the flame or flame front. ... 

Contrast C is the contrast of the luminances between the object Lo and its surroundings Ls C = (Lo - Ls)/Ls. With increasing contrast, visibility increases Adaptation luminance L,d, is the luminance to which the eye adapts its sensitivity. It corresponds to the luminance of the field of vision. With increasing adaptation luminance, visibility increases. 

The visibility level VL of special viewing tasks may be estimated from the the correlations of the quantitative visual recognition. For an adaptation luminance of 10 cd/m2 and given contrasts (C = 0.5 1.0 2.0), VL is described in Fig. 1 in dependance on the object dimension 3 in angular minutes. An object dimension of T represents a circle with a diameter of 0 12 mm in a distance of 0 4 m. 

B MTU-MK MTU/bright indication (Luminance) MTU-MS MTU/vreak indications (Luminance)... 

Below Difference of the luminances Li - Ls in dependanee of the field strength H,... 

Assuming C = 1.0 (Indication luminance a factor 2 higher than the background) we get the nominal values from Fig. 1 ... 

Moerner W E 1994 Fundamentals of single moleoule speotrosoopy in solids J. Lumin. 60-61 997-1002... 

Kopelman R, Tan Wand Birnbaum D 1994 Subwavelength spectroscopy, exciton supertips and mesoscopic light-matter interactions J. Lumin. 58 380-7... 

Doniey E A, Burzomato V, Wiid U P and Piakhotnik T 1999 The distribution of iinewidths of singie probe moiecuies in a crystaiiine host at miiiiKeivin temperatures J. Lumin. 83-84 255-9... 

Tittel J, Kettner R, Basche T, Brauchle C, Quante FI and Mullen K 1995 Spectral diffusion in an amorphous polymer probed by single molecule spectroscopy J. Lumin. 64 1-11... 

Guttler F, Sepiol J, Plakhotnik T, Mitterdorfer A, Renn A and Wild U P 1993 Single molecule spectroscopy fluorescence excitation spectra with polarized light J. Lumin. 56 29-38... 

Myers A B, Tchenio P and Moerner W E 1994 Vibronic spectroscopy of single molecules exploring electronic-vibrational frequency correlations within an inhomogeneous distribution J. Lumin. 58 161-7... 

Tchenio P, Myers A B and Moerner W E 1993 Optical studies of single terrylene molecules in polyethylene J. Lumin. 56 1-14... 

There is no satisfactory chemical way of distinguishing betn een ethane and methane, both of which burn with an almost non-luminous flame this fact however is quite unimportant at this stage of the investigation. Hydrogen also burns with a non-luminous flame and w hen the open end of a test-tube full of the gas is placed in a Bunsen flame, a mild explosion with a very characteristic report takes place. 

The Evolution of Methyl Iodide. The flask A (Fig. 89) is now heated with the non-luminous flame of the micro-burner. The immediate result of the heating will be an increase in the rate of bubbles passing up the absorption spiral no endeavour should be made to decrease this flow, however, as it will return to the original rate as soon as the hydro-... 

Push one end of a length of 20 cm. of stout copper wire into a cork (this wUl serve as a holder) at the other end make two or three turns about a thin glass rod. Heat the coil in the outer mantle of a Bunsen dame until it ceases to impart any colour to the dame. Allow the wire to cool somewhat and, while still warm, dip the coil into a small portion of the substance to be tested and heat again in the non-luminous dame. If the compound contains a halogen element, a green or bluish-green dame will be observed (usually after the initial smoky dame has disappeared). Before using the wire for another compound, heat it until the material from the previous test has been destroyed and the dame is not coloured. 

Assemble the apparatus shown in Fig. 1 V, 67, 1 this is self-explanatory. The distilling flask has a capacity of 250 ml. and the beaker contains 150 ml. of 10 per cent, sodium hydroxide solution. All corks must fit well and should be coated with paraflSn wax (by dipping into molten wax, and allowing to drain). Place half of the yield of the dry phenyldiazonium fluoborate in the distilling flask. Heat the solid gently with a small luminous flame at one point near its surface until decomposition begins withdraw the flame and allow the reaction to continue... 

Phenylethylbarbituric acid (also termed luminal and phenobarbitone) may be prepared by condensing ethyl phenyletUylmalonate with urea in the presence of sodium methoxide ... 

Place 25 g. of methyl methacrylate polymer (G.B. Diakon (powder). Perspex (sheet) U.S.A. Lucite, Plexiglass) in a 100 ml. Claisen flask, attach an efficient condenser e.g., of the double smface type) and distil with a small luminous flame move the flame to and fro around the sides of the flask. At about 300° the polymer softens and undergoes rapid depolymerisation to the monomer, methyl methacrylate, which distils over into the receiver. Continue the distillation until only a small black residue (3-4 g.) remains. Redistil the hquid it passes over at 100-110°, mainly at 100-102°. The yield of methyl methacrylate (monomer) is 20 g. If the monomer is to be kept for any period, add 0 -1 g. of hydro quinone to act as a stabiUser or inhibitor of polymerisation. 

Deuterium is used as a moderator to slow down neutrons. Tritium atoms are also present but in much smaller proportions. Tritium is readily produced in nuclear reactors and is used in the production of the hydrogen (fusion) bomb. It is also used as a radioactive agent in making luminous paints, and as a tracer. 

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