Radiation inversion

Type of inversion Radiation (ground) Subsidence (overhead)... 

The formation of thermal inversions is one of the most important meteorological factors contributing to air pollution problems in urban areas. There are two major sources of thermal inversions. Radiation (or... 

M. Oguma and J. R. Howell, Solution of T vo-Dimensional Blackbody Inverse Radiation by an Inverse Monte Carlo Method, Proc. 4th ASMEIJSME Joint Symposium, Maui, March, 1995. 

Let the problem of focusing laser radiation into the smooth curve L have a smooth solution function (p, rf)e.C (G). Then the inverse image of each point M ff) EiL is a certain segment F (ff) S G. ... 

For this kind of case, a modification of the dilution method is being developed. Instead of using an external fixed-geometry measurement chamber, a suitable part of the process, e.g. a stretch of pipe, is used. A radiation detector is mounted on the outside of the pipe, and a tracer emitting sufficiently hard gamma radiation is used. As sufficient mixing can be achieved by injecting upstream the separator the radiation level found will be strictly proportional to the concentration and thus inversely proportional to the true flow rate. 

A number of surface-sensitive spectroscopies rely only in part on photons. On the one hand, there are teclmiques where the sample is excited by electromagnetic radiation but where other particles ejected from the sample are used for the characterization of the surface (photons in electrons, ions or neutral atoms or moieties out). These include photoelectron spectroscopies (both x-ray- and UV-based) [89, 9Q and 91], photon stimulated desorption [92], and others. At the other end, a number of methods are based on a particles-in/photons-out set-up. These include inverse photoemission and ion- and electron-stimulated fluorescence [93, M]- All tirese teclmiques are discussed elsewhere in tliis encyclopaedia. 

Fig. 27. Scanning electron micrograph (a) and cross-sectional comparison (b) of screen and depth filters both having a nominal particulate cut-off of 0.4 flm. The screen filter (a Nuclepore radiation track membrane) captures particulates at the surface. The phase-inversion ceUulosic membrane traps the...

An inversion caused by mixing in a surface layer was just discussed above. Inversions at the surface are caused frequently at night by radiational cooling of the ground, which in turn cools the air near it. 

Graphite will creep imder neutron irradiation and stress at temperatures where thermal creep is normally negligible. The phenomenon of irradiation creep has been widely studied because of its significance to the operation of graphite moderated fission reactors. Indeed, if irradiation induced stresses in graphite moderators could not relax via radiation creep, rapid core disintegration would result. The observed creep strain has traditionally been separated into a primary reversible component ( ,) and a secondary irreversible component (Ej), both proportional to stress and to the appropriate unirradiated elastic compliance (inverse modulus) [69]. The total irradiation-induced creep strain (ej is thus ... 

Wavelength, A (Section 12.5) The length of a wave from peak to peak. The wavelength of electromagnetic radiation is inversely proportional to frequency and inversely proportional to energy. 

Notice from this equation that energy is inversely related to wavelength. This explains why you put on sunscreen to protect yourself from UV solar radiation (<400 nm) and a lead apron when dental x-rays (<10 nm) are being taken. Conversely, IR (>700 nm) and micro-wave photons (>80,000 nm) are of relatively low energy (but don t try walking on hot coals). 

Lightman A., Ben-Reuven A. Line mixing by collisions in the far-infrared spectrum of ammonia, J. Chem. Phys. 50, 351-3 (1969) Cross relaxation in the rotational inversion doublets of ammonia in the far infrared, J. Quant. Spectrosc. Radiat. Transfer 12, 449-54 (1972). 

---