Condon field emission

Field electron emission coupled with flash-filament studies have been employed by Condon and Hansen to study benzene chemisorption on tungsten (21). Evidence was obtained for the chemisorption of benzene by a single bond (probably of -character) to the surface. This form of asso-ciatively adsorbed benzene [(I), Scheme 1] appeared to exist in equilibrium with cr-adsorbed-CeHs (II) and adsorbed atomic hydrogen. 

Fig. 5. Energy level diagram for Pd(2-thpy)2 dissolved in n-octane. The Tj state at 18,418 cm is zero-field split on the order of 0.2 cm. The emission decay times refer to the individual triplet suhstates I, II, and III, respectively, at T = 1.3 K. (Compare Fig. 6.) These suhstates are radiatively deactivated as purely electronic transitions, as well as by Franck-Condon (FC) and Herzberg-Teller (HT) vibrational activity, respectively. This leads the different vibrational satellites. (Compare also Sects. 4.2.2 and 4.2.3.) The lifetime of the S, state is determined from the homogeneous linewidth of the spectrally resolved Sq —> S, electronic origin. (Sect. 3.2) The electronic state at 24.7 x 10 cm is not yet assigned...

The explanation, which was given independently by Gamow and by Condon and Gurney (1928), depends on a deep-seated distinction between quantum mechanics and ordinary mechanics, which is of importance in other cases also (as in cold electron emission, p. 222). In order to get a mechanical picture of the binding of an a-particle to the rest of the nucleus, we must imagine a field of force which holds... 

Much of the work on solvation effects has concentrated on modeling the shift of the centre of an electronic absorption or emission band that occurs on solvation, i.e.. the solvatochromic shift. According to the Franck-Condon principle the centre of such a band corresponds to the vertical excitation energy (from an initial to final electronic state) at a fixed nuclear geometry. Solvation of a chromophore thus implies that while the system in its initial electronic state is in equilibrium with its environment, it is not so in its vertically excited state. On excitation of the solute the electronic polarization of the solvent is assumed to relax instantaneously while the ori-entational/distortional polarization is thought of as remaining frozen, a view which may be somewhat simplistic. Within the reaction-field model application of the above theory to a solvated dipole results in a solvent shift of... 

Fig. 27. By applying a magnetic field the wavefunctions of the states 11) and II > mix. The matrix element shown symbolizes this mechanism, which provides allowedness to the transition from the perturbed state Ig) to the ground state 10). Using this process it is possible to continuously tune the vibrational satellite structure in emission. At B = 0 T the spectrum is dominated by Herzberg-Teller (HT) induced satellites, while with increasing field strength the electronic origin and Franck-Condon (f C) satellites strongly grow in. This is seen in the spectra reproduced in Fig. 24...

Fig. 29. Magnetic field dependence J. c, T = 2 K) of the emission intensity of a typical Franck-Condon-induced vibrational satellite of [Osfbpy-hg) ) doped into [Ru(bpy-hjljKPFjlj [92J. This satellite grows in with the extent of admixture of state II) into state 11) (see Figs. 27,28). The good fit to a dependence indicates the applicability of first-order perturbation theory [180]...

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