Quasi-atomic state

It was also observed, in 1973, that the fast reduction of Cu ions by solvated electrons in liquid ammonia did not yield the metal and that, instead, molecular hydrogen was evolved [11]. These results were explained by assigning to the quasi-atomic state of the nascent metal, specific thermodynamical properties distinct from those of the bulk metal, which is stable under the same conditions. This concept implied that, as soon as formed, atoms and small clusters of a metal, even a noble metal, may exhibit much stronger reducing properties than the bulk metal, and may be spontaneously corroded by the solvent with simultaneous hydrogen evolution. It also implied that for a given metal the thermodynamics depended on the particle nuclearity (number of atoms reduced per particle), and it therefore provided a rationalized interpretation of other previous data [7,9,10]. Furthermore, experiments on the photoionization of silver atoms in solution demonstrated that their ionization potential was much lower than that of the bulk metal [12]. Moreover, it was shown that the redox potential of isolated silver atoms in water must... 

In addition to the quasi-steady state assumption, the other assumptions required to arrive at equation (1) are 1. the aerosol itself does not coagulate 2. there is a fully developed concentration gradient around each aerosol particle and 3. the concentration of unattached radon progeny atoms is much greater than the concentration of aerosol particles (in order that concentration gradients of radon progeny atoms may exist). This last assumption is usually not valid since the radon progeny concentration is usually much less than the aerosol concentration. 

Simple calculation gives a comparable distribution of the electrode potential in the two layers, (64< >h/64( sc) = 1 at the surface state density of about 10cm" that is about one percent of the smface atoms of semiconductors. Figure 5—40 shows the distribution of the electrode potential in the two layers as a function of the surface state density. At a surface state density greater than one percent of the surface atom density, almost all the change of electrode potential occurs in the compact layer, (6A /5d )>l, in the same way as occurs with metal electrodes. Such a state of the semiconductor electrode is called the quasi-metallic state or quasi-metallization of the interface of semiconductor electrodes, which is described in Sec. 5.9 as Fermi level pinning at the surface state of semiconductor electrodes. 

We have already mentioned (expressions 30—33) the widely used LEPS surface for atom-diatom reactions. This may be regarded as purely empirical or semi-empirical in any modification in which some integrals are evaluated. Another system for which fairly elaborate potential functions have been used is for non-reactive atom-diatom scattering. The experiment for which the potential is designed is the change of rotational or vibrational state of a diatomic molecule by collision with a third atom, and also the quasi bound states, which may be observed spectroscopically, of van der Waals molecules such as Ar—H2 (133). 

Atoms are diffusing into the boundary laterally from its edges and can diffuse out through its front face into the forward grain. At the same time, atoms will be deposited in the backward grain in the wake of the boundary. In the quasi-steady state in a coordinate system fixed to the moving boundary, the diffusion flux in the forward grain is J = — DXL(dc/dx) — vc and the diffusion equation is... 

The situation becomes quite different when the a//3 interface is no longer capable of maintaining the concentration of B atoms in its vicinity at the equilibrium value c 0. If the concentration there rises to the value ca0, the instantaneous quasi-steady-state current of atoms delivered to the particle by the diffusion field (obtained from Eq. 13.22) will be given by... 

Resonances are common and unique features of elastic and inelastic collisions, photodissociation, unimolecular decay, autoionization problems, and related topics. Their general behavior and formal description are rather universal and identical for nuclear, electronic, atomic, or molecular scattering. Truhlar (1984) contains many examples of resonances in various fields of atomic and molecular physics. Resonances are particularly interesting if more than one degree of freedom is involved they reflect the quasi-bound states of the Hamiltonian and reveal a great deal of information about the multi-dimensional PES, the internal energy transfer, and the decay mechanism. A quantitative analysis based on time-dependent perturbation theory follows in the next section. 

Each of the potentials shown in Figure 12.5 supports at least one bound or quasi-bound state which can be labeled by quantum numbers (j, Cl, J). These zeroth-order states correspond to almost free rotation of HF within the van der Waals complex with quantum numbers j = 0,1,2,... and Cl = 0,1,2,..., min(j, J). In analogy with the nomenclature for electronic states, they are termed E and n for Cl = 0 and 1, respectively. For j = 1 and Cl = 0 the diatom rotates in the plane defined by the three atoms. In contrast, for j = 1 and Cl = 1 it rotates in a plane perpendicular to the intramolecular vector R. As J increases, the centrifugal potential h2[J(J + 1) + j(j + 1) — 2Cl2]/2mR2 increases as well and eventually Veff(R j,Cl,J) becomes purely repulsive and the sequence of bound or quasi-bound states breaks off. 

If we represent the quasi-bound state of the rapidly exchanging (on average 1/e times) vacancy and impurity atom with the position of a bond of the original lattice, then the vacancy-tracer pair walks... 

Unlike molecular solvents, charge-dipole interaction cannot be expected between closed-shell atoms and excess electrons. However, finite and infinite ensembles of rare-gas atoms can support a bound and/or quasi-bound state for electrons, due solely to the collective polarization of the surrounding atoms. In bulk Xe, for instance, the conduction band lies 0.7 eV below the vacuum level [62]. The formation of negatively charged clusters has also been reported for He [35 37], Ne [38]... 

One of the important issues addressed in our simulations is the character of clusters under study. Are these clusters solid or liquid rmder experimental conditions If they arc liquid, then the distribution wc observe in the pick-up and consequently in the photodissociation simulations corresponds to a statistical distribution at a. given temperature. If, however, the cluster is solid then both in the simulations and in the cxj)eriment we observe a quasi-stationary state with a very long lifetime rather than an equilibrium thermodynamical state. This question can be resolved by means of the instantaneous normal modes (INM) density of states (DOS) spectrum. To calculate INM DOS wc construct the Hessian matrix in a mass-weighted atomic Cartesian coordinate basis of N atoms with /r=. r, y, z. The 3N eigenvectors in the form Ci -.Cjj,Cj-,C2, C2/,C2-,.c.vj.,ca/j,c.v de-... 

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