Plasma resonance states

Investigations on the doubly excited states of two electron systems under weakly coupled plasma have been performed by several authors. Such states usually occur as resonance states in electron atom collisions and are usually autoionizing [225]. Many of these states appear in solar flare and corona [226,227] and contribute significantly to the excitation cross-sections required to determine the rate coefficients for transitions between ionic states in a high temperature plasma. These are particularly important for dielectronic recombination processes which occur in low density high temperature plasma, occurring e.g. in solar corona. Coronal equilibrium is usually guided by the balance between the rates of different ionization and... 

Further evidence that TmS is trivalent comes from XPS measurements by Campagna et al. (1976) or Baer et al. (1994), shown in fig. 59, completed by a BIS spectrum by Baer et al. (1994). The occupied states clearly yield a 4f" 4f" final state spectrum as shown by the ladder-like structure given in the figure, where the initial 4f 4fstate of trivalent Tm is about 6.5 eV below E. There is an indication of a divalent spectrum which is attributed to surface states, but part of the 5d band is also occupied. This is corroborated by the metallic character of TmS as judged from resistivity versus temperature curves and from the golden color of the crystals typical for the plasma resonance of trivalent sulfides with one 5d electron. 

Another remarkable feature measured in CeCu is the temperature dependence of the plasma resonance cUp of the heavy quasiparticles, which has been found near 150meV at 5 K and from which the quasiparticle concentration and the eflTective mass has been deduced (with the help of the y value). We show in fig. 143 the plasma frequencies obtained from the optical data at different temperatures. The value at 1.4 K (the asterisk) has been reported from millimeter-wave data from Beyermann et al. (1988) and has a value of about 200 meV, which agrees quite reasonably with our 150 meV It is remarkable that the plasma frequency preserves practically the same small value up to a temperature of about 20 K. This is in contrast with what one expects from a simple Kondo model where the characteristic temperature for the formation of a resonant state has been estimated to be between 3 and 6K (Satoh et al. 1985, Steglich et al. 1985, Onuki et al. 1984). Up to room temperature the plasma frequency continuously shifts to 2-3 eV, which means that... 

As I look back at this experience, it was an awesome adventure to be alone, during and for an interval of time after this discovery, with the apparatus showing one new effect after another, when there was no one in the Illinois Physics Department experienced in NMR with whom I could talk. Little did the early NMR resonance community realize that the analogue of spin echo hidden memory contained in excited phases of all kinds of states of matter, including plasmas, would be obtained in the future by use of optical laser, electric, and acoustic pulses as well. And now today the use of spin echoes is a standard procedure for magnetic resonance imaging of the human body for medical diagnosis. 

A. Wennmalm, B. Lanne, and A.S. Petersson, Detection of endothelial-derived relaxing factor in human plasma in die basal state and following ischemia using electron-paramagnetic resonance spectrometry. Anal. Biochem. 187, 359-363 (1990). 

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