Lithium-like system

The method is based on the nearly complete cancellation between the target excitation energy and the binding energy of the attached electron for certain low-energy resonances. For a lithium-like system, a resonance can be formed in the following way ... 

As in the case of a hyperfine structure, there is a wealth of new experimental data on Lamb shift measurements of such exotic systems as lithium-like uranium U89+, again encouraging the relevant calculations [164-166],... 

The relative reactivities of pyridine, 3-picoline, and 3-ethylpyridine toward phenyllithium have been measured under various conditions by a competitive technique and found to be in the order 3-pico-line > pyridine > 3-ethylpyridine.252 By carrying out reactions using an equimolar mixture of pyridine and 3-picoline and a large excess of phenyllithium, it has been possible to obtain yields of the phenyl-pyridines of over 80%, provided short reaction times and low temperatures are used. It has also been shown that the low yields usually obtained in such reactions are due to the fact that the dihydropyridyl-lithium intermediates form by-products, probably by polymerization (the intermediate dihydropyridine is a ct s-butadiene-like system and, in the presence of a Ziegler-type catalyst, can be expected to polymerize readily). The a-complexes from 3-picoline and phenyllithium polymerize faster than that from pyridine and phenyllithium, but there is no selective removal of the isomeric dihydropicolyllithium intermediates to form by-products, both isomers undergoing side-reactions at virtually the same rate. 

Helium is not the only three body system under study, but it is likely the most complicated one. The electron-electron interaction is comparable with the electron-nucleus interaction and cannot be considered as a perturbation. The situation is different with helium-like (and lithium-like) ions, where the electron-electron interaction is as small as 1 jZ with respect to the interaction of an electron and the nucleus. 

A wide variety of plasma diagnostic applications is available from the measurement of the relatively simple X-ray spectra of He-like ions [1] and references therein. The n = 2 and n = 3 X-ray spectra from many mid- and high-Z He-like ions have been studied in tokamak plasmas [2-4] and in solar flares [5,6]. The high n Rydberg series of medium Z helium-like ions have been observed from Z-pinches [7,8], laser-produced plasmas [9], exploding wires [8], the solar corona [10], tokamaks [11-13] and ion traps [14]. Always associated with X-ray emission from these two electron systems are satellite lines from lithium-like ions. Comparison of observed X-ray spectra with calculated transitions can provide tests of atomic kinetics models and structure calculations for helium- and lithium-like ions. From wavelength measurements, a systematic study of the n and Z dependence of atomic potentials may be undertaken. From the satellite line intensities, the dynamics of level population by dielectronic recombination and inner-shell excitation may be addressed. 

Using the finite-size scaling method, study of the analytical behavior of the energy near the critical point shows that the open-shell system, such as the lithium-like atoms, is completely different from that of a closed-shell system, such as the helium-like atoms. The transition in the closed-shell systems from a bound state to a continuum resemble a first-order phase transition, while for the open-shell system the transition of the valence electron to the continuum is a continuous phase transition [9]. 

To examine the behavior of open-shell systems, let us consider the scaled Hamiltonian of the lithium-like atoms ... 

Now, let us use the data collapse method to test the hypothesis of finite-size scaling used to obtain the critical parameter for this system and estimate the critical exponent v for the lithium-like atoms. Using data collapse to the ionization energy of the three-electron atom in its ground state, /3(A) = Eq1(A)—... 

The reduction of a. -unsaturated carbonyls with lithium in ammonia is a versatile reaction of great utility. The advantage of this method is that regiospecific enolates are obtained that are sometimes not accessible by other routes. This technique finds important applications in steroid-like systems (equation 15). °... 

The high reactivity of chelated lithium alkyl compounds severely limits structural study of pure compounds, particularly in aromatic solvents. Most of our more recent work on chelated lithium alkyl systems used H and 7Li NMR to observe various metalation reactions like the self-metalation or aging reaction of TMED LiBu in heptane (I, 2). Much of our current insight into the structural features of chelated alkali metal systems comes from careful quantitative study of systems with relatively stable anions like resonance stabilized carbanions (5) and the systems described in this paper. We discuss magnetic resonance experiments on two systems (a) chelated lithium halides Chel LiX, examples of the recently discovered inorganic salt chelates (6), and (b)... 

For small systems, like hydrogen-, helium-, and lithium-like atoms, there is a possibility that more acciurate methods of QED could be used. 

In our laboratory a series of laser-microwave studies has been performed on metastable and short-lived excited states of heliumlike Li. Singly ionized lithium, like all members of the two-electron He isoelectronic sequence, belongs to the fundamental systems in atomic physics. Many of its spectroscopic and quantum-mechanical characteristics have been calcu-... 

Figure 7.2 Examples of possible battery systems. Some of them are hypothetical, some important for today s portable applications like nickel/metal hydride or lithium ion systems are not shown.

X-rays from a few electron systems such as hydrogenlike, helium-like, lithium-like ions are observed in hot... 

Miniature applications have become more important in recent years with the general aeeeptance of the behind-the-ear hearing-aid and the advent of the electronic watch. High energy density per unit volume is the prime requirement for a battery in these products. The mercuric oxide-zinc, silver oxide-zinc, zinc-air and lithium-based systems appear to be likely contenders for this market. Although the last two types of battery have been produced in sizes suitable for miniature applications, they are not widely available in this format. These systems will therefore be discussed later in their usual cylindrical form, and the conclusions drawn then may explain the difficulties that have prevented their wide acceptance. 

Despite the statement above concerning the acid lability of cyclic formals, Gold and Sghibartz have shown that the acid catalyzed hydrolysis of these compounds is markedly depressed by some metal ions . Although the smaller cyclic formals did not exhibit a substantial rate reduction even in the presence of small cations like lithium, in certain larger systems the rate reduction was more than an order of magnitude. 

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