Plasmon states

In atomic-molecular media the damping of plasmon states is due to the interaction of plasmon waves with electrons, lattice vibrations, and impurities. The electron-plasmon interaction is a long-range one. With absorption of a plasmon, the momentum q is transferred to the electron, resulting in a decay of the collective state into a single-particle one. The latter process is identical with absorption of a photon with the same energy. Wolff102 (see also Ref. 103) has shown that in this case the lifetime can be expressed in terms of two optical constants the absorption coefficient k and the refractive index nT, namely,... 

For water, at frequencies around that of the plasmon state hestimated using the uncertainty relation. From the energy-loss spectrum in water we find that the half-width of the excitation level hwr = 21.4eV amounts to about 3.4 eV. This gives us r = (1/A[Pg.284]

Delocalization due to Energy Transfer to the First Singlet State hiu0l =8.4eV and to the Plasmon State h(or = 21.4 eV in Water by an Electron with Energy Et... 

Thus, part of the energy transferred to a molecular medium by a charged particle is certainly delocalized. And though later this energy is localized on one of the molecules, this localization is stochastic, and thus the coordinates of the points of ionization and excitation cannot be determined more precisely than to within the magnitude of bpl or Ax we have presented previously. This circumstance is important, first of all, when one simulates tracks of charged particles using the Monte Carlo method, where the track is presented as a set of points where the interaction took place.302 303 Even if the plasmon states are not formed in the system, the... 

According to these results, despite the fact that plasmon states absorb about 30% of the energy of a primary electron in water, this has little effect of the yield of primary active particles after the plasmon states have decayed. The authors also did not observe any noticeable decrease in the average energy spent on formation of an ion pair W, with transition from steam to liquid water. 

Valence electrons also can be excited by interacting with the electron beam to produce a collective, longitudinal charge density oscillation called a plasmon. Plas-mons can exist only in solids and liquids, and not in gases because they require electronic states with a strong overlap between atoms. Even insulators can exhibit... 

The degree of surface cleanliness or even ordering can be determined by REELS, especially from the intense VEELS signals. The relative intensity of the surface and bulk plasmon peaks is often more sensitive to surface contamination than AES, especially for elements like Al, which have intense plasmon peaks. Semiconductor surfaces often have surface states due to dangling bonds that are unique to each crystal orientation, which have been used in the case of Si and GaAs to follow in situ the formation of metal contacts and to resolve such issues as Fermi-level pinning and its role in Schottky barrier heights. 

Sometimes it is possible to distinguish surface and bulk plasmons by lowering Eq so that the bulk plasmon will decrease in intensity more rapidly than the surface plasmon. However both surface states and interband transitions can show the same behavior. 

A comparison of the results in Sections 3.1 and 3.2 describing two very different methods implies that the 1.4nm size obviously plays a significant role. In the plasmon studies it is the first in the row of known particles that does not show a resonance with visible light, in case of the presented relaxation behaviour it represents the species just one step before the molecular state. 

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