Hot LIPS In Focus!

HotLIPS  In Focus!

Laser-induced plasma spectroscopy (LIPS) is considered to be the oldest spectroscopic technique employing high-peak power laser pulses. When such pulses are focused onto the surface of a solid material, a short-lived, high-density and temperature plasma is generated on that surface. These laser-produced plasmas, which containing a diversity of atomic and ionic species, emit radiation over an extensive spectral range stretching from the IR (infra-red) to the X-ray region. The well-established generic technique has been used since its first introduction in 1962 for the direct quantitative elemental characterization of almost every type of solid materials.

A background and introduction, as well as an overview on the history and development of the LIPS technique are briefly discussed. Also, experimental investigations into the elemental characterization of steel alloys by the technique are given in some details, as a case study.

Brane World Physics

The most successful theory in Physics, the Standard Model, cannot explain
the huge energy gap between the electroweak scale and the Planck scale a puzzle known as the Hierarchy Problem. To achieve the unification of all known forces in nature, the gravitational interaction should be made
comparable in strength to all other interactions. So far physicists were trying to "push up" the electroweak scale by introducing new symmetries (such as Supersymmetry) in the Standard Model. Supersymmetry achieved very high energies, but not enough to reach the Planck scale. In the past four years a radically different approach was proposed: modify space-time, Gravity and the Planck scale itself by the introduction of extra
dimensions. This mechanism "lowered" the Planck scale significantly and has no contradiction to any experiment whatsoever.
String Theory, the leading candidate to become the theory of the grand
unification, is a unique theory that incorporates all main principles
discovered in Physics: Quantum Mechanics, Gauge Theory and General
Relativity.
This talk will give a brief introduction to the basic ideas of String
Theory and the Universe's "unseen dimensions".
 

Sir George Gabriel Stokes: the man and his phenomenon today

Born in Skreen, County Sligo, Stokes occupied the prestigious Lucasian
chair of mathematics in the University of Cambridge for 53 years, until his death in 1903. His name occurs today throughout physics, although his major contributions were in fluid dynamics (the Navier-Stokes equations), polarisation of light (the Stokes coefficients) and asymptotic analysis (the Stokes phenomenon).

This talk will present an account of his life, a review of his physical work and a deeper discussion of his original asymptotic analysis of Airy's integral for caustics behind rainbows. Further details, and photographs, can be seen on Alistair's web pages. 
http://webpages.dcu.ie/~wooda/stokes/ggstokes.html
 

A Test of Intuition: The Structures of Weak Adsorbates on Metal Surfaces

Nearly 10 years ago, it was discovered that alkali metal atoms adsorbed on metal surfaces sometimes occupy the low-coordination adsorption sites. This result was surprising because, until then, it was generally believed that atomic adsorbates prefer to occupy sites of high coordination, in order to maximize their bonding to the surface. The many detailed experiments and the density-functional theory calculations that followed eventually resolved this paradox by demonstrating that the essential feature which determined the preferred site was not the adsorption site, but the depth to which the adatom could penetrate the surface. It turned out that the low-coordination structures generally included a significant rumpling of the substrate in order to accommodate the penetration of the atoms into the surface. 
The energy to cause this deformation of the surface apparently came from the chemisorption energy of the adatoms.  It was therefore a great surprise when, more recently, it was discovered that rare gas atoms also prefer the low-coordination sites on metal surfaces.  In this case, the adsorption energy is too small to support any significant rumpling of the substrate, and yet the
preference for top sites has been demonstrated by several different experiments.  These experimental results for rare gases adsorbed on metal surfaces, some new density-functional theory results, and some plausible explanations will be presented, followed by some even stranger preliminary measurements of the structures of Xe adsorbed on a quasicrystal surface.
 

Quantum computation : Theory and implementations
We will introduce the subject of quantum information processing at a theoretical level. We then will describe briefly a number of physical implementations for a quantum information processor currently under intense research throughout the world. We will finally present a new design for a novel molecular-based quantum computer using doped fullerenes and compare the predicted design specs for this type of quantum computer with other implementations.

Design and synthesis of novel materials and
structures using pulsed laser deposition

An important challenge in modern condensed matter physics is the discovery
and characterization of novel technological materials. As our understanding
of materials properties deepens, there has been a change to the approach to
this problem, encompassed by the concept of ``materials by design'': no
longer are substances fabricated, and their possible applications
subsequently investigated. Instead, the modern procedure is to tailor
materials apriori for a required purpose.
This has been made possible by an increased competence in three research
areas: theoretical modelling of materials; the development of novel
synthetic techniques for producing new chemical systems; and the
development of powerful techniques in materials analysis.

An novel adaptation of pulsed laser deposition is presented, called pulsed
reactive crossed-beam laser ablation (PRCLA). It is shown that the addition
of a synchronized pulsed valve lends both technological and fundamental
advantages. Examples of materials and structures grown using PRCLA are
given, and forthcoming projects using PRCLA at the new materials science
beamline at the Swiss Light Source are also covered.

Reaching the Limits:
Making Contact with Molecules and Nanocrystals

Philip Moriarty
School of Physics & Astronomy,University of Nottingham

Nanoscale science is not only an integral component of modern physics but a subject that is inherently multidisciplinary in character ­ the traditional boundaries between the physical, chemical, and biological sciences effectively vanish at the nanometre level. This makes nanoscience an exciting and vibrant field of modern research. In this talk a number of key areas of state-of-the-art nanoscience will be discussed including: sub-nanometre precision manipulation of single atoms and molecules (see Fig.1 and Fig.2), the electronic properties of novel fullerene and carbon nanotube systems, and the low dimensional physics and chemistry of metal and semiconductor nanocrystals containing a ‘countable’ number of atoms. Both the relationship of nanotechnology with more conventional areas of solid state/ condensed matter science and the future prospects for nanostructured materials and nanodevices will be covered. A particular focus will be on distinguishing between current nanotechnology which has a sound scientific basis and that which is likely to remain within the realms of science fiction.
Fig.1 Quantum ‘mirages’
within corrals formed from positioning
individual Co atoms on a Cu surface
(Manohararan et al. Nature 403 512)

Fig.2 Scanning tunnelling
microscope-constructed fullerene
nanostructures