43 research outputs found
Surface plasma resonance in small rare gas clusters by mixing IR and VUV laser pulses
The ionization dynamics of a Xenon cluster with 40 atoms is analyzed under a
pum p probe scenario of laser pulses where an infrared laser pulse of 50 fs
length follows with a well defined time delay a VUV pulse of the same length
and peak intensity. The mechanism of resonant energy absorption due to the
coinc idence of the IR laser frequency with the frequency of collective motion
of quasi free electrons in the cluster is mapped out by varying the time delay
between the pulses
Enhanced ionization in small rare gas clusters
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
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.
Labour Relations and Modes of Employment
Seventh Framework Programme (FP7)info:eu-repo/grantAgreement/EC/FP7/266833Hervorming Sociale Regelgevin
Changing perspectives on the internationalization of R&D and innovation by multinational enterprises: a review of the literature
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 âfoundation textsâ. 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
European integration, regional growth and cohesion
This special issue of the International Journal for Public Policy focuses on the effects of European integration on regional production structures, in particular in border regions, as well as economic interactions across border regions in the enlarged European Union (EU). Furthermore, we discuss the impact of transport, cohesion and Information and Communication Technologies (ICT) policies on border regions and more broadly on regional growth and cohesion. Copyright © 2008, Inderscience Publishers