49 research outputs found

    Enhanced ionization in small rare gas clusters

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    A detailed theoretical investigation of rare gas atom clusters under intense short laser pulses reveals that the mechanism of energy absorption is akin to {\it enhanced ionization} first discovered for diatomic molecules. The phenomenon is robust under changes of the atomic element (neon, argon, krypton, xenon), the number of atoms in the cluster (16 to 30 atoms have been studied) and the fluency of the laser pulse. In contrast to molecules it does not dissappear for circular polarization. We develop an analytical model relating the pulse length for maximum ionization to characteristic parameters of the cluster

    Dynamical ionization ignition of clusters in intense and short laser pulses

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    The electron dynamics of rare gas clusters in laser fields is investigated quantum mechanically by means of time-dependent density functional theory. The mechanism of early inner and outer ionization is revealed. The formation of an electron wave packet inside the cluster shortly after the first removal of a small amount of electron density is observed. By collisions with the cluster boundary the wave packet oscillation is driven into resonance with the laser field, hence leading to higher absorption of laser energy. Inner ionization is increased because the electric field of the bouncing electron wave packet adds up constructively to the laser field. The fastest electrons in the wave packet escape from the cluster as a whole so that outer ionization is increased as well.Comment: 8 pages, revtex4, PDF-file with high resolution figures is available from http://mitarbeiter.mbi-berlin.de/bauer/publist.html, publication no. 24. Accepted for publication in Phys. Rev.

    Changing perspectives on the internationalization of R&D and innovation by multinational enterprises: a review of the literature

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    Internationalization of R&D and innovation by Multinational Enterprises (MNEs) has undergone a gradual and comprehensive change in perspective over the past 50 years. From sporadic works in the late 1950s and in the 1960s, it became a systematically analysed topic in the 1970s, starting with pioneering reports and “foundation texts”. Our review unfolds the theoretical and empirical evolution of the literature from dyadic interpretations of centralization versus decentralization of R&D by MNEs to more comprehensive frameworks, wherein established MNEs from Advanced Economies still play a pivotal role, but new players and places also emerge in the global generation and diffusion of knowledge. Hence views of R&D internationalization increasingly rely on concepts, ideas and methods from IB and other related disciplines such as industrial organization, international economics and economic geography. Two main findings are highlighted. First, scholarly research pays an increasing attention to the network-like characteristics of international R&D activities. Second, different streams of literature have emphasized the role of location- specific factors in R&D internationalization. The increasing emphasis on these aspects has created new research opportunities in some key areas, including inter alia: cross-border knowledge sourcing strategies, changes in the geography of R&D and innovation, and the international fragmentation of production and R&D activities

    Grain Marketing Facilities and Practices in South Carolina

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    Excerpts from the report: This study was made at the request of the Extension Service of Clemson Agricultural College. Its purpose was to obtain and evaluate information relating to ( 1 ) the quantity and quality of grains marketed in South Carolina, (2) the types and adequacy of grain-handling facilities, (3) the location of such facilities with respect to grain production and consumption areas, (4) the local grain marketing practices, and (5) recommendations for improving the grain marketing system and handling facilities in the various production and consumption areas in the State. A field survey of grain-handling facilities was made during the summer of 1953 through personal interviews with all the principal grain buyers and handlers in the State, as well as many small buyers and processors. Observations were made as to the numbers, sizes, and types of grain-handling facilities, their location in relation to production and consumption areas, and the marketing practices and local customs followed in the receiving, handling, care, and shipping of whole grain. Information was furnished by local grain handlers as to the quantity of each grain of the 1952 crop that was bought from farmers, from local dealers, and from other sources, and the utilization made of each type of grain that was bought

    Über den Aufbau der Chrom-MolybdĂ€n-Legierungen

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    Modelling dynamics of samples exposed to free-electron-laser radiation with Boltzmann equations

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    We apply Boltzmann equations for modelling the radiation damage in samples irradiated by photons from free electron laser (FEL). We test this method in a study case of a spherically symmetric xenon cluster irradiated with VUV FEL photons. The results obtained demonstrate the potential of the Boltzmann method for describing the complex and non-equilibrium dynamics of samples exposed to FEL radiation.Comment: 31 pages, 11 figure
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