Thermal absorptivity/effusivity

Fig. 4.11 Determination of the velocity distributions n(v ) and n(v i) by measuring the Doppler profile of absorption lines in a thermal, effusive NO2 beam [409]...

A collimated effusive molecular beam with a rectangular density profile behind the collimating aperture has a thermal velocity distribution at T = 500 K. Calculate the intensity profile a oS) of an absorption line, centered at two for molecules at rest, if the beam of a weak tunable monochromatic laser crosses the molecular beam under 45° against the molecular beam axis... 

The mechanism has not been completely elucidated, and it has been established that this effect is not necessarily connected with hydrogen effusion from the film. The change observed in the IR spectra in the Si—H absorption region after extended illumination is considerable. For example, illumination by a 16 AMl solar spectrum over 400 h decreases the absorption coefficient in the 2000-2100-cm region by a factor of 1.5, although subsequent thermal annealing restores it to its initial value [133]. 

For surface heated inhomogeneous samples, thermal waves experience reflection or absorption when they encounter buried interfaces wherein there is a change in the thermal effusivity ratio ... 

Indices i and j refer to adjacent layers, kj and kj (W m s ) are thermal conductivities, and D, and Dj are the thermal diffusivities. Thermal effusivity is analogous to a refractive index for thermal waves. Reflection and absorption may be evaluated by the thermal reflection coefficient ... 

Glycoside linkage a C—O—C bond formed between the rings of two cyclic monosaccharides by the elimination of water. (22.6) Graham s law of effusion the rate of effusion of a gas is inversely proportional to the square root of the mass of its particles. (5.7) Greenhouse effect a warming effect exerted by the earth s atmosphere (particularly COj and H2O) due to thermal energy retained by absorption of infrared radiation. (6.5)... 

From the maximum of the shifted absorption profile the most probable velocity Vp can be deduced [10.17]. Figure 10.6b illustrates the measurement of velocity distributions of Na molecules in specified quantum states at different oven temperatures. The narrowing of the velocity distribution with increasing oven temperature and the increase of the most probable velocity Vp characterize the transition region from a thermal effusive molecular beam to a supersonic beam. The velocity distribution in the supersonic beam can be described by... 

---