Bottleneck behavior

YbAl2 has an anomalously large electronic specific heat coefficient 17mJ/molK. This may indicate an intermediate valence state in YbAla at low temperatures. Furthermore all dialuminides show bottleneck behavior in the Gd and Eu ESR experiments and hence allow to determine the relaxation rate 5 . Levin et al. (1982) investigated YbA (R = Nd, Eu, Gd, Dy, Er) and reported the observation of bottleneck situations for Eu and Gd as ESR probes. They broke the bottleneck by the addition of nonmagnetic thorium ions or by diminution of the Gd and Eu concentration and reached the isothermal limits Ago=+0.09 0.01 and dA/f/dT=25 5G/K for Gd and Ago = +0.06 0.01 and... 

The ESR-spectra of Gd or other lanthanide ions in van-Vleck hosts all reveal similar features large g-shifts relative to the undisturbed g-value and thermal broadenings of the linewidths, which are typically nonlinear functions on temperature. These general features sometimes are influenced by additional Korringa processes. In certain cases a bottleneck behavior can be detected. The giant g-shifts are connected with the large susceptibilities, Xw, of the van-Vleck host emu/mol) and with the total exchange interaction... 

In the case of Gd " in praseodymium an ESR signal with g = 2.3 0.1 and a linewidth, A/f=1600G has been observed (Al tshuler et al. 1981). Mi does not depend on temperature. The authors explain this behavior assuming a bottleneck behavior in this system. 

Commercial surfactants are, in general, chemically impure and may contain varying amounts of water and additives. After prolonged storage of liquid nonionic surfactants the composition tend to change. It should be observed that even trace impurities might sometimes produce a bottleneck in carrying out spectroscopic studies of proteins/nucleic acids in RMs. In addition, the impurities may interfere with the behavior of biomolecules and also cause problems of reproducibility. To achieve reproducible results, it is advisable to purify the surfactants to be used whenever possible [121. 

Meffert, L.M. and Bryant, E.H. (1991). Mating propensity and courtship behavior in serially bottlenecked lines of the housefly. Evolution, 45, 293-306. 

The fact that classical unstable periodic trajectories can manifest themselves in the Wigner function implies that nonstatistical behavior in the quanmm dynamics can be intimately related to the phase-space structure of the classical molecular dynamics. Consider, for example, the bottlenecks to intramolecular energy flow. Since the intramolecular bottlenecks are caused by remnants of the most robust tori, they are presumably related to the least unstable periodic trajectories. Hence quantum scars, being most significant in the case of the least unstable periodic trajectories, are expected to be more or less connected with intramolecular bottlenecks. Indeed, this observation motivated a recent proposal [75] to semiclassically locate quantum intramolecular bottlenecks. Specifically, the most robust intramolecular bottlenecks are associated with the least unstable periodic trajectories for which Eq. (332) holds, that is,... 

The effective Hamiltonian approach clearly shows the important role of intramolecular energy flow in the quantum dynamics of unimolecular dissociation. It suggests that unless intramolecular energy flow is dominantly rapid, there exist two drastically different time scales in the reaction dynamics. This is consistent with the classical concept that nonstatistical behavior in intramolecular energy flow, such as bottleneck effects, can dramatically alter the kinetics of unimolecular reaction. 

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