Emissivity of surfaces

Static SIMS entails the bombardment of a sample surface with an energetic beam of particles, resulting in the emission of surface atoms and clusters. These ejected species subsequendy become either positively or negatively charged and are referred to as secondary ions. The secondary ions are the actual analytical signal in SIMS. A mass spectrometer is used to separate the secondary ions with respect to their charge-to-mass ratios. The atomic ions give an elemental identification (see... 

Table 1 indicates methods for evaluating FA and FE for several simple cases. Table 2 lists the emissivities of surfaces commonly encountered in industrial operations. Additional tables, plots, and methods for evaluating the correction factors are available in the various texts and handbooks on heat... 

So far only one specific characteristic of computed surface potentials seems to have an important effect on experimental results. For thermionic emission of surfaces subject to an electric field, the Richardson equation must be modified in two ways. First the potential barrier is lowered by the electric field to give a new work function. In addition the reflection coefficient is altered. The relative current )/ 0 as a function of applied field E becomes... 

Seidel, J., Grafstrom, S., and Eng, L. (2005) Stimulated Emission of Surface Plasmons at the Interface between a Silver Film and an Optically Pumped Dye Solution. Physical Review Letters 94 177401. 

Building compunents often involve trapped airspaces between various layers. Thermal resistances of such air spaces depend on the thickness of the layer, the temperature difference across the layer, the mean air temperature, tb eniissivity of each surface, the orientation of the air layer, and the directioy Of heat transfer. The emissivities of surfaces commonly encountered in buildings are given in Tabic 3—10. The effective emissivity of a plane-pafaiict air space is given by... 

Table A-2 Boiling and freezing point properties 843 Table A-3 Properties of solid metals 844 846 Table A-4 Properties of solid nonmetals 847 Table A-5 Properties of building materials 848-849 Table A-6 Properties of insulating materials 850 Table A-] Properties of common foods 851-852 Table A-8 Properties of miscellaneous materials 853 TableA-9 Properties of saturated water 854 Table A 10 Properties of saturated refrigerant-134a 855 Table A-11 Properties of saturated ammonia 856 Table A-12 "Properties of saturated propane 857 Table A-13 Properties of liquids 858 Table A-14 Properties of liquid metals 859 Table A- 5 Properties of air at 1 atm pressure 860 TableA-16 Properties of gases at 1 atm pressure 861-862 Table A-17 Properties of the atmosphere at high altitude 863 Table A-18 Emissivities of surfaces 864-865 Table A-19 Solar radiative properties of materials 866 Figure A-20 The Moody chart for friction factor for fully developed flow in circular pipes 867...

Economic lot size, 350 Effective interest, 218-222, 224, 241 Efficiency, packing, 702-706 plate, 661-667 pump, 517-518, 520 Ejectors, cost of, 528 Electrical installation, cost of, 174, 807 Electricity, cost of, 815 Electromotive series of metals, 433 Emissivity of surfaces, 582-585 Energy balance, mechanical, 479-480 for reactor design, 715-716 total, 479-480... 

A simple example is a small body that is not black surrounded by a black surface. Let the areas of the enclosed and surrounding surfaces be A and A2, respectively, and let their temperatures be Tj and T2, respectively. The radiation from surface A2 falling on surface A is crA2F2iTt. Of this, the fraction i, the absorbtivity of area for radiation from surface A2, is absorbed by surface A. The remainder is reflected back to the black surroundings and completely reabsorbed by the area A2. Surface emits radiation in amount aAiSiTt, where Si is the emissivity of surface A. AH this radiation is absorbed by the surface A2, and none is returned by another reflection. The emissivity 61 and absorptivity aj are not in general equal, because the two surfaces are not at the same temperature. The net energy loss by surface is... 

Laser-Etching Process. In certain photo-etching processes, a laser pointed at a target area rg causes an emission of surface atoms with a gaussian distribution in velocities, i.e., we have the initial state for the single atom distribution function as (see Fig. 2.4)... 

The ion-bombardment-induced emission processes include electrons and photons, besides the emission of surface particles (atoms or molecules) in a charged or uncharged, and possibly excited, state. All of these emission products are emitted with a certain angular distribution. 

Additional applications of the SPR phenomenon include using the surface plasmon electromagnetic waves to excite emission of surface-bound chromo-phores, to enhance Raman spectra (surface-enhanced Raman spectroscopy), and as surface-bound light in optical microscopy. 

A complete analysis of the thermal emission of surface species and their measurements has been reported [71]. A problem of extending the emission technique to surface analysis is that strong background emission can be superimposed on the weaker emission from the surface. Thus the ideal sample for emission studies is a very thin surface layer supported on a perfect reflector. An experimental emission sampling system designed specifically for the study of surface species has been described [72]. 

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