251 research outputs found

    Observation of dipolar-induced spin dephasing in ionic solids using coherent optical-microwave spectroscopy

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    The observation of spin dephasing in an ensemble of dipolar coupled A and B spins is reported. In CaO crystals, the A-spin species are photoexcited S=1, F22+ centers and the group of B spins consists of S=1 / 2, F+ centers. Measurements were made at different temperatures and magnetic field strengths with use of coherent optical-microwave spectroscopy. For the first time, the results show that the A-spin dephasing is influenced by exchange narrowing in the B-spin ensemble

    Energy and phase relaxation of phosphorescent F centers in CaO

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    In this paper we study the temperature‐induced homogeneous broadening of the no‐phonon line in the emission spectrum of the F center in CaO. The linewidth can be fitted to n(n+1), where n is the thermally averaged occupation number of phonons with a frequency of 90 cm^(−1). The results are characteristic of elastic scattering of pseudolocalized phonons at the defect site. These phonons also appear to dynamically couple the Jahn–Teller components of the F center in the photoexcited^3 T_(1u) state and thus give rise to a temperature dependence of the lifetime of this phosphorescent state. Finally, from experiments using laser‐selective excitation it is concluded that the zero‐phonon emission peaking at 571.1 nm does not originate in the F center

    Corporate environmental responsibility and criminology

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    This article addresses corporate environmental responsibility (CER) and aims to present a criminological analysis of it. We studied the opinion of a number of principle actors involved in CER in Europe in order to determine how they perceive it in terms of its definition, aetiology and approaches. For each of these dimensions we relate back to a criminological framework to ascertain how it is positioned in the green criminological debate. We start out by providing information on what corporate environmental responsibility is and how it relates to corporate social responsibility and sustainable development. Then we outline the theoretical framework in accordance with the three central themes for the criminological analysis of CER: definition, aetiology and approaches. We also explain the method that was used (semi-structured interviews). Next, we present the results according to the same threefold structure. Finally we discuss these results in a last part, which is divided in two. First, we look at the challenges that the criminological perspective poses for CER in terms of definition, aetiology and approaches. The second part of the discussion turns the question around and wonders how CER could contribute to greening criminology
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