Phase-resolved Photoacoustic Spectroscopy And Epr Investigation Of Mno2- And Coo-doped Soda-lime Glasses

A discussion on the use of the phase shifts of the photoacoustic signal of different constituents of a composite sample for resolving their individual spectra is presented. It is experimentally shown that as long as we are interested in a qualitative analysis the method is simple and fast. For a quantitative analysis in which the nonradiative relaxation time and the characteristic diffusion time within the optical-absorption depth are sought, the method presents some limitations. This is demonstrated using MnO2- and CoO-doped soda-lime silica glass samples. © 1989 The American Physical Society.40318801884CAS; Chinese Academy of Sciences; DFG; Chinese Academy of Sciences; NRF; Chinese Academy of Sciences; NSFC; Chinese Academy of Sciences; PSI; Chinese Academy of Sciences; RAS; Chinese Academy of Sciences; RFBR; Chinese Academy of Sciences; RPF; Chinese Academy of Sciences; STFC; Chinese Academy of Science

Thermal Diffusivity Of Palladium-hydrogen Systems At Room Temperature Using Photothermal Detection

We report results of measurements on the thermal diffusivity, specific heat and electrical resistivity of hydrogenated-palladium samples. It is shown that repetition of the hydrogenation process with the same sample induces aging effects, which lead to erroneous results. The results for the thermal-property measurements on single-cycled palladium samples reflected a phase transition between -PdH and -PdH as the hydrogen concentration is increased. © 1992 The American Physical Society.4595031503

Energy-resolved spatial inhomogeneity of disordered Mott systems

We investigate the effects of weak to moderate disorder on the T=0 Mott metal-insulator transition in two dimensions. Our model calculations demonstrate that the electronic states close to the Fermi energy become more spatially homogeneous in the critical region. Remarkably, the higher energy states show the opposite behavior: they display enhanced spatial inhomogeneity precisely in the close vicinity to the Mott transition. We suggest that such energy-resolved disorder screening is a generic property of disordered Mott systems.Comment: 6 pages, 6 figures. Submitted to the Proceedings of the SCES 200

Photoacoustic And Esr Studies Of Iron-doped Soda-lime Glasses: Thermal Diffusivity

The photoacoustic technique is used to measure the thermal diffusivity of iron-doped soda-lime glasses. To explain the thermal diffusivity behavior as a function of the iron content in the samples, electron-spin-resonance data were used. It is concluded that the main reason for the observed changes in the thermal diffusivity is the ferric ion entering substitutionally at the Si4+ sites. © 1989 The American Physical Society.40117912791

Photoacoustic Monitoring Of Magnetite-crystal Formation From Iron(iii) Hydroxide Acetate: Comparison With Esr Results

The formation of crystalline magnetite by 1-h heat treatment of iron(III) hydroxide acetate is described. This amorphous-crystalline solid transformation is monitored by electron-spin resonance and photoacoustic spectroscopies. No significant changes were detected for samples heated below 190 °C. Above this temperature both techniques presented results following a definite pattern, namely, the enhancement of ion mobility leading to particle growth and crystallization for a temperature up to 240 °C and the onset of magnetic ordering of magnetite near this temperature.65125150515

Correlações entre médias de híbridos F1 e medias parentais em tomate

In a six parent tomato (Lycopersicon esculentum Mill) diallel cross, specific heterosis was more important for marketable yield (PFC) than for its components - average weight (PMFC) and number of marketable fruit (NFC). Correlation coefficients between F1 hybrid means and parental means were larger for PMFC and NFC than for PFC. The product of PMFC by NFC parental means can be used more efficiently as an estimate of F1 hybrid PFC's than PFC parental means themselves.Em cruzamento dialélico de seis cultivares de tomate (Lycopersicon esculentum Mill), a heterose específica foi mais importante para produção de frutos comerciáveis (PFC) do que para suas componentes peso médio (PMFC) e número de frutos comerciáveis (NFC). Os coeficientes de correlação entre médias de híbridos F1 e médias parentais foram maiores para PMFC e NFC do que para PFC. O produto das médias parentais de PMFC e NFC pode ser utilizado para estimar a PFC dos híbridos com mais eficiência do que a PFC média parental propriamente dita

Quantum Griffiths effects and smeared phase transitions in metals: theory and experiment

In this paper, we review theoretical and experimental research on rare region effects at quantum phase transitions in disordered itinerant electron systems. After summarizing a few basic concepts about phase transitions in the presence of quenched randomness, we introduce the idea of rare regions and discuss their importance. We then analyze in detail the different phenomena that can arise at magnetic quantum phase transitions in disordered metals, including quantum Griffiths singularities, smeared phase transitions, and cluster-glass formation. For each scenario, we discuss the resulting phase diagram and summarize the behavior of various observables. We then review several recent experiments that provide examples of these rare region phenomena. We conclude by discussing limitations of current approaches and open questions.Comment: 31 pages, 7 eps figures included, v2: discussion of the dissipative Ising chain fixed, references added, v3: final version as publishe