J. Mareš

Chirally motivated K− nuclear potentials

Abstract In-medium subthreshold K ¯ N scattering amplitudes calculated within a chirally motivated meson–baryon coupled-channel model are used self consistently to confront K − atom data across the periodic table. Substantially deeper K − nuclear potentials are obtained compared to the shallow potentials derived in some approaches from threshold K ¯ N amplitudes, with Re V K − chiral = − ( 85 ± 5 ) MeV at nuclear matter density. When K ¯ N N contributions are incorporated phenomenologically, a very deep K − nuclear potential results, Re V K − chiral + phen . = − ( 180 ± 5 ) MeV , in agreement with density dependent potentials obtained in purely phenomenological fits to the data. Self consistent dynamical calculations of K − –nuclear quasibound states generated by V K − chiral are reported and discussed.

Wave equations with energy-dependent potentials

We study wave equations with energy-dependent potentials. Simple analytical models are found useful to illustrate difficulties encountered with the calculation and interpretation of observables. A formal analysis shows under which conditions such equations can be handled as evolution equation of quantum theory with an energy-dependent potential. Once these conditions are met, such theory can be transformed into ordinary quantum theory.

Widths of K¯-nuclear deeply bound states in a dynamical model

Abstract The relativistic mean field (RMF) model is applied to a system of nucleons and a K ¯ meson, interacting via scalar and vector boson fields. The model incorporates the standard RMF phenomenology for bound nucleons and, for the K ¯ meson, it relates to low-energy K ¯ N and K − atom phenomenology. Deeply bound K ¯ nuclear states are generated dynamically across the periodic table and are exhibited for 12 C and 16 O over a wide range of binding energies. Substantial polarization of the core nucleus is found for these light nuclei. Absorption modes are also included dynamically, considering explicitly both the resulting compressed nuclear density and the reduced phase space for K ¯ absorption from deeply bound states. The behavior of the calculated width as function of the K ¯ binding energy is studied in order to explore limits on the possible existence of narrow K ¯ nuclear states.

Calculations of K− nuclear quasi-bound states based on chiral meson–baryon amplitudes

In-medium K¯N scattering amplitudes developed within a new chirally motivated coupled-channel model due to Cieplý and Smejkal that fits the recent SIDDHARTA kaonic hydrogen 1s level shift and width are used to construct K− nuclear potentials for calculations of K− nuclear quasi-bound states. The strong energy and density dependence of scattering amplitudes at and near threshold leads to K− potential depths −ReVK≈80–120 MeV. Self-consistent calculations of all K− nuclear quasi-bound states, including excited states, are reported. Model dependence, polarization effects, the role of p-wave interactions, and two-nucleon K−NN→YN absorption modes are discussed. The K− absorption widths ΓK are comparable or even larger than the corresponding binding energies BK for all K− nuclear quasi-bound states, exceeding considerably the level spacing. This discourages search for K− nuclear quasi-bound states in any but the lightest nuclear systems.

Glassy, Amorphous and Nano-Crystalline Materials

Glassy, Amorphous and Nano-crystalline Material: Thermal Physics, Analysis, Structure and Properties includes twenty-one chapter contributions from an international array of distinguished academics based in Asia, Australia, Eastern and Western Europe, Russia, and the USA. The book provides a coherent and authoritative overview of cuttingedge themes involving the thermal analysis, applied solid-state physics and the microcrystallinity of selected materials and their macroand microscopic thermal properties. Selected chapters featured in the book include: Essential attributes of glassiness regarding the nature of non-crystalline solids; Aspects of vitrification, amorphization, disordering and the extent of nano-crystallinity; The basic role of thermal analysis in polymer physics; Classical and quantum diffusion and their application to the self-organized oscillatory reactions; Specificity of low temperature measurements applied to nano-crystalline diamante; Thermophysical properties of natural glasses at the extremes of the thermal history profile; Phenomenological meaning of temperature as background for the history and development of thermal analysis and calorimetry. Advanced undergraduates, postgraduates and researchers working in the field of thermal analysis and calorimetry will find this contributed volume invaluable.

Quantum aspects of self-organized periodic chemical reactions

It is a remarkable empirical fact, known for a long time, that in certain self-organized periodic chemical reactions, such as Liesegangs or Belousov-Zhabotinskys reactions, the product of molecular weight of precipitate, precipitation length period, and speed of precipitation is of the order of universal Plancks quantum of action h. Based on the fact that the classical and quantum diffusions are processes, which are indistinguishable in the configuration space, a quantum criterion in terms of diffusion constants has been established. This criterion enables one to find out conditions under which the quantum behavior of self-organized periodic reactions can be observed.

On space-charge-limited conduction in semi-insulating GaAs

Abstract We have measured the temperature dependence of Cr doped semi-insulating (SI) GaAs in planar and point contact configurations at various fields ranging between 10 and 10 6 V/m. In a planar configuration the transport is ohmic up to ∼ 10 4 V/m with an activation energy of ∼ 0.75 eV. At higher fields we have observed a space-charge-limited (SCL) transport with an activation energy of about 0.47 eV. In a point contact configuration a quasi-ohmic and a transitional region have been found, both having an activation energy of ∼ 0.47 eV. Such behaviour is in qualitative agreement with Lamperts theory of SCL conduction. Some deviations from this theory are accounted for by the existence of macroscopic screening length in SI-GaAs.

Historical Roots and Development of Thermal Analysis and Calorimetry

Apparently, the first person which used a thought experiment of continuous heating and cooling of an illustrative body was curiously the Czech thinker and Bohemian educator [1], latter refugee Johann Amos Comenius (Jan Amos Komenský, 1592–1670) when trying to envisage the properties of substances. In his “Physicae Synopsis”, which he finished in 1629 and published first in Leipzig in 1633, he showed the importance of hotness and coldness in all natural processes. Heat (or better fire) is considered as the cause of all motions of things. The expansion of substances and the increasing the space they occupy is caused by their dilution with heat. By the influence of cold the substance gains in density and shrinks: the condensation of vapor to liquid water is given as an example. Comenius also determined, though very inaccurately, the volume increase in the gas phase caused by the evaporation of a unit volume of liquid water. In Amsterdam in 1659 he published a focal but rather unfamiliar treatise on the principles of heat and cold [2], which was probably inspired by the works of the Italian philosopher Bernardino Telesius. The third chapter of this Comenius’ book was devoted to the description of the influence of temperature changes on the properties of substances.

Hyperon - nucleus scattering in Dirac phenomenology

Abstract Optical potentials for Λ and ϵ scattering off nuclei are developed based on a global nucleon-nucleus Dirac optical potential and the constituent-quark-model values of the meson-baryon coupling constants. The differential cross section and analyzing power are calculated for a few energies and nuclei. The tensor coupling has a large effect on the predictions for the analyzing power.

Synthesis, structure, and opto-electronic properties of organic-based nanoscale heterojunctions

Enormous research effort has been put into optimizing organic-based opto-electronic systems for efficient generation of free charge carriers. This optimization is mainly due to typically high dissociation energy (0.1-1 eV) and short diffusion length (10 nm) of excitons in organic materials. Inherently, interplay of microscopic structural, chemical, and opto-electronic properties plays crucial role. We show that employing and combining advanced scanning probe techniques can provide us significant insight into the correlation of these properties. By adjusting parameters of contact- and tapping-mode atomic force microscopy (AFM), we perform morphologic and mechanical characterizations (nanoshaving) of organic layers, measure their electrical conductivity by current-sensing AFM, and deduce work functions and surface photovoltage (SPV) effects by Kelvin force microscopy using high spatial resolution. These data are further correlated with local material composition detected using micro-Raman spectroscopy and with other electronic transport data. We demonstrate benefits of this multi-dimensional characterizations on (i) bulk heterojunction of fully organic composite films, indicating differences in blend quality and component segregation leading to local shunts of photovoltaic cell, and (ii) thin-film heterojunction of polypyrrole (PPy) electropolymerized on hydrogen-terminated diamond, indicating covalent bonding and transfer of charge carriers from PPy to diamond.