Evaporation Theory

The evaporation rate ( ) obtained for an extensive, wet surface in dynamic equilibrium with the atmosphere and in the absence of advection may be written (Slatyer and Mcllroy, 1961 Mc-Naughton, 1976) as 

FIGURE 4 (A) Relations between daily clear-sky shortwave irradiance at 

To illustrate the application of Eq. (1), we can conduct a global average annual computation. The global average surface temperature is 15°C according to Graedel and Crutzen (1993). At this temperature, A = 2.465 J g and e/(e + 1) = 0.63. For the earth s continents, Baumgartner and Reichel (1975) estimate RJ = 850 mm year so that E = 535 mm year . This may be compared 

For plant leaves, the surface may be considered explicitly by a model of E or transpiration rate ( ,)  

The value of E in relation to like the value of gj, indicates the evaporative nature of the surface so E E q or E/Ee, 1 reflects surface dryness or stomatal closure as well as the balance of energy exchange between the atmosphere and the underlying surface. By definition, E Ef, can be caused only by advection. As implied above with respect to the partitioning of temperature, this may also result from the entrainment of dry air from above the convective boundary layer that develops daily over the earth surface. To further illustrate the relation between E and Ef, in terms of surface characteristics, it is helpful to write the Penman-Monteith equation (Monteith and Unsworth, 1990), 

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Anderson el al. (A4), 1961 Theoretical and experimental study of heat transfer to liquid films in vertical long-tube evaporators. Theory based on use of universal velocity profile. 

Water droplets were collected by the immiscible liquid method of Fraser and Eisenklam (8) at 2.4, 3.9, and 5.9 feet downwind from the spray nozzle. The observed impacting droplet sizes showed excellent agreement with the predicted sizes (Table I), thus lending confidence to the use of in-flight evaporation theory as a tool for interpreting wind tunnel spray drift data. 

Young E. D., Nagahara H., Mysen B. O., and Audet D. M. (1998) Non-Rayleigh oxygen isotope fractionation by mineral evaporation theory and experiments in the system Si02. Geochim. Cosmochim. Acta 62, 3109—3116. 

L vov [95] has re-analyzed the published results for LijSO. HjO dehydration in terms of his dissociative evaporation theory (see Section 2.4.6.) and is able to explain the variations in the reported values by taking into account the inhibiting effect of water vapour on the rate of dehydration and the contributions fi om the condensation of Li2S04(g). 

Drop evaporation theory for spherical and ellipsoidal drops... 

Those nucleons which do not escape from the nucleus are assumed to share their energy with the entire residual nucleus. This leads to the second phase, namely the de-excitation of an excited nucleus. The dissipation of this energy is conveniently treated by the statistical model of the nucleus and the evaporation theory of Weisskopf. ... 

The thermodynamic treatment has been applied mainly to understanding stars in photographic emulsions. The end products are also the radioactive nuclei observed in radiochemical studies. The appUcation of evaporation theory to prediction of the yields of radioisotopes is rather hmited (see Morrison [2]). The form that a more general application might take may be indicated by Hal-pern s treatment of the yield of radioisotopes from photo-nuclear reactions (see Sect. 47). 

For present purposes this particular series of papers is important because the authors later used a mass spectrometer for the first time (Thomson 1979) to characterize the charged species produced by their spray technique (Figure 5.25). Equally important, the authors introduced the ion evaporation theory for the mechanism whereby single molecular ions are formed from charged droplets (see later). It was soon realized that this... 

Individual properties of specific ions and solvents are included in k, mainly via the AG°qj.j, term. The preceding account does not do justice to the sophistication of the ion evaporation theory or its recent experimental tests (Gamero-Castafio 2000), but wiU suffice for present purposes. 

Figure 2.9 Ionization mechanisms in ESI. (a) Schematic illustration of the single ion in droplet theory and (b) ion evaporation theory...

Quantity YOM Cross Sections Parker Cross Sections Evaporation Theory with Temperature Reduced 30% ... 

Figure 1.6 Predictions of the ion evaporation theory [34]. The Rayleigh curve provides the droplet radius R and the number of elementary charges N at w/hich a charged water droplet will be at the Rayleigh limit. Solvent evaporation at constant charge to a smaller radius R will cause a Coulomb fission. Similarly, the curves Cation Cluster and Anion Cluster show the threshold of ion evaporation at a given charge N and droplet radius R. For negatively charged droplets,...

Electrospray ionization mass spectrometry is typically performed in polar solvents such as water, acetonitrile, methanol, or a combination of these. Thus, analytes with significant nonpolar regions should favor the air-solvent interface at the surface of electrospray droplets where these nonpolar regions can be desolvated. Such analytes are termed smface-active. A relationship between response in atmospheric pressure ionization mass spectrometry and analyte surface activity was postulated as early as 1983 by Mbame et al., the original authors of the ion evaporation theory. Such a relationship was also observed by Kebarle and co-workers," " who included a factor related to analyte surface activity in their models. 

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