- Published on 23 June 2010
The shape of the interface between two fluids can be controlled by changing the refractive index contrast between the fluids, researcher from the Universite Bordeaux have shown. Optofluidics are methods based on the combination of optics and fluidics which have recently promoted innovative approaches to manipulate liquid interfaces. Since flows are optically driven, researchers call this emerging field optohydrodynamics. The recent paper published in EPJ E presents a fine example of optohydrodynamic actuation at the microscopic scale, based on experimental and predictive numerical results. This work illustrates one of the simplest manifestations of optohydrodynamics and provides a frame to anticipate further developments of contactless interface micromanipulation by lasers.
To read the full paper ‘Optohydrodynamics of soft fluid interfaces: Optical and viscous nonlinear effects’ by H. Chraibi et al. click here
- Published on 21 June 2010
This July, during the International Soft Matter Conference 2010 in
Granada, Spain, Professor Sam Safran will give the EPJ E - Pierre
Gilles De Gennes lecture, associated with a prize given by the
publishers of EPJ.
This is the first edition of the *EPJE - Pierre-Gilles De Gennes Lecture Prize*, which takes the name from the illustrious Nobel laureate who founded EPJ E.
The Editors in Chief elected Prof. Sam Safran of the Weizman Instutite, Israel, as the prize recipient to acknowledge his leading research in soft matter and biological physics. The prize was also endorsed by the ISMC 2010 conference committee.
The prize will be presented to Prof. Sam Safram by Prof. Dominique Langevin (who is an Associate Editor of EPJ E) at the beginning of his plenary talk, 6 July at 8.30 am.
If you wish to vist the ISMC 2010 website go to http:/ismc2010.ugr.es/
- Published on 17 June 2010
Stark deceleration has emerged over the last decade as a leading technique for obtaining packets of quantum-state-selected molecules whose velocity can be tuned all the way down to zero. Here, a new compact, ultrahigh-vacuum-compatible Stark decelerator is described and demonstrated. The deceleration stages are fashioned out of tantalum wires, reducing the total length to about a tenth of that of a conventional Stark decelerator with the same number of electrode pairs.
The significantly lower cost of assembling and operating the wire decelerator makes it an attractive source of cold molecules, for use in applications ranging from trapping experiments to cold collisions to sympathetic cooling.
A. Marian, H. Haak, P. Geng, and G. Meijer, Eur. Phys. J. D (2010)
- Published on 17 June 2010
Structural, optical and nanomechanical properties of nanocrystalline Zinc Telluride (ZnTe) films of thickness upto 10 microns deposited at room temperature on borosilicate glass substrates are reported. X-ray diffraction patterns reveal that the films were preferentially oriented along the (1 1 1) direction. The maximum refractive index of the films was 2.74 at a wavelength of 2000 nm. The optical band gap showed strong thickness dependence. The average film hardness and Young's modulus obtained from load-displacement curves and analyzed by Oliver-Pharr method were 4 and 70 GPa respectively. Hardness of (1 1 1) oriented ZnTe thin films exhibited almost 5 times higher value than bulk. The studies show clearly that the hardness increases with decreasing indentation size, for indents between 30 and 300 nm in depth indicating the existence of indentation size effect. The coefficient of friction for these films as obtained from the nanoscratch test was ~0.4.
Structural, optical and nanomechanical properties of (111) oriented nanocrystalline ZnTe thin films, M.S.R.N. Kiran, S. Kshirsagar, M.G. Krishna and S.P. Tewari (2010), Eur. Phys. J. Appl. Phys. DOI 10.1051/epjap/2010071
- Published on 11 June 2010
Only one liquid exhibits Bose-Einstein condensation in nature: Helium II, . At such temperatures, all other substances are solid. In these two papers, Vitaly Golovko demonstrates that Bose-Einstein condensation can also occur in the solid state. Moreover, it is shown that at 0 K, a condensate crystal is energetically preferable with respect to the same quantum crystal without condensate. Therefore, on lowering the temperature of the crystal there must somewhere happen Bose-Einstein condensation, as in liquid helium. This opens a huge field for experimental investigations of Bose-Einstein condensation and of its influence on properties of solids.
- Published on 17 May 2010
Our understanding of elasticity, plasticity and failure in non-crystalline solids has greatly enhanced through atomic scale simulation. A new Colloquium paper In EPJ B reviews a variety of computational approaches that have been successful in elucidating the atomic scale phenomena that control the mechanics of amorphous solids. The constitutive theories that have been developed for describing mechanical response are briefly illustrated, as well as the prospects for testing the assumptions of these theories using simulation. The authors, M.L. Falk and C.E. Maloney, pose the most pressing open questions for substantiating these theoretical approaches, and ultimately for understanding and predicting the mechanical behaviour of amorphous solids.
To read the full paper "Simulating the mechanical response of amorphous solids using atomistic methods" by M.L. Falk and C.E. Maloney, European Physical Journal B click here.
- Published on 03 May 2010
Keiichiro Nasu reviews models of photo-induced structural phase transitions in relation to recent experimental results on unconventionally photoactive solids, where the relaxation of optical states results in macroscopic excited domains with new structural and electronic orders. Two key concepts, the hidden multi-stability of the ground state and proliferations of optically excited states are discussed. Taking the ionic to neutral phase transition in an organic charge-transfer crystal as example, the author documents the fundamental nature of photo-induced structural phase transitions. Further, Nasu recounts the details of the discovery of a new photo-induced phase of carbon, named "diaphite", located in between graphite and diamond. The mechanism of this photo-induced structural phase transition is discussed in terms of the proliferation of photo-generated inter-layer charge-transfer excitations in the visible regime.
To read the full paper 'sp3 domain in graphite by visible light and photoinduced phase transitions' by K. Nasu, European Physical Journal B click here.
- Published on 26 April 2010
Kurt Becker, Associate Provost at the Polytechnic Institute of NYU and Editor in Chief of EPJ D, was awarded the 2010 SASP Erwin Schrödinger Medal. The announcement was made in January 2010 during the Symposium of Atomic, Cluster, and Surface Physics (SASP) held in Obergurgl, Austria. Dr. Becker was cited for his “outstanding scientific achievements and contributions to research in molecular physics – specifically, the interaction of electrons with molecules and clusters – as well as in the properties and applications of plasmas”. The medal is named after the Austrian theoretical physicist Schrödinger, who won the Nobel Prize in 1933 for his work on the development and formulation of quantum mechanics. The entire journal team is delighted for Kurt Becker and congratulates him on this prestigious achievement.
- Published on 19 April 2010
Photodetachment microscopy provides the best electron affinity measurements on atoms and molecules. Photodetachment of a negative ion produces a nearly free electron, hardly perturbed by the residual atomic core. Applying an external electric field does not only concentrate the photoelectron current in a round spot, but also gives rise to an electron interference pattern, due to the existence of a pair of possible trajectories bound to every point of the spot. This very fundamental matter-wave interferometer produces extraordinarily robust interferograms. Although magnetic fields, even in the sub-microT range, causes fluxes between the interfering trajectories that can be huge compared to the quantum unit of magnetic flux, a magnetic perturbation of the system appears to only produce a global deviation of the spot, without any modification of the interference pattern. The main result of the recent paper published in EPJ D by Chaibi et al. is that even in higher magnetic fields (typically 100 microT) the electron interference phase, or number of interference rings, remain unperturbed. This comfirms photodetachment as a highly accurate method for electron spectrometry and electron affinity measurements.
To read the full paper ‘Effect of a magnetic field in photodetachment microscopy’ by W. Chaibi et al., Eur. Phys. J. D (2010) click here
- Published on 14 April 2010
Quantum memories are essential elements for many potential applications of quantum technology. Research on the development of such memories is currently very lively, with a particular emphasis on memories that can interface with photons, which are the best carriers of quantum information over long distances. A Colloquium paper in the May issue on EPJ D reviews a number of different approaches to this challenge, with a focus on the approaches that were represented in the large European Union Integrated Project "Qubit Applications". This Colloquium covers solid-state atomic ensembles, nitrogen-vacancy centres, quantum dots, single atoms and atomic gases. Since the considered approaches are very diverse, an important part of the work was to establish criteria that allow a meaningful comparison. The authors discuss both the current experimental state of the art and the potential long-term performance of the various systems.
To read the full paper ‘Quantum Memories’ by C. Simon et al. click here