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Grupo QI

Público·36 miembros
Carter Thompson
Carter Thompson

Atomic And Molecular Physics By Rajkumar


Abstract: Self-assembled germanium islands have been grown on Si (001) substrates using solid source molecular beam epitaxy. A series of annealing experiments have been performed at a temperature 650C in order to clarify some issues related to island stability and coarsening mechanism. The shape and size distribution of Ge islands as a function of annealing time up to 90 min have been studied through atomic force microscopy. Foot-prints of the annealed and etched islands have demonstrated that the coarsening is dominated by coalescence mechanisms rather than the Ostwald ripening. A detailed Raman characterisation, using optical phonons as efficient probes in analysing self-organised Si1-xGex islands, is reported. The alloy composition has been determined from the Raman intensities. The experimental results are in good agreement with the strain relaxation obtained from X-ray rocking curve and data from AFM topographic images. The generic mechanisms for the growth of self-assembled Ge islands as a function of growth parameters and post-growth treatment are also reviewed.




atomic and molecular physics by rajkumar



Large-scale molecular dynamics simulations are performed to investigate the atomiclevel stresses on InAs/GaAs mesas. The simulations are based on an interatomic-potential scheme for InAs/GaAs systems which depends on the local chemical composition. Multiresolution techniques are used to speed up the simulations. InAs/GaAs square mesas with 101 -type sidewalls are studied. The atomic-level pressure distribution and surface atomic stresses on the sidewalls with 12, 10, 8 and 6 monolayers of InAs overlayers have been calculated.


Along with previous research that has demonstrated crystal motion in other types of crystals, the new results suggest that crystals appear to be promising candidates for robotics. [26] The search and manipulation of novel properties emerging from the quantum nature of matter could lead to next-generation electronics and quantum computers. [25] A research team from Lab) has found the first evidence that a shaking motion in the structure of an atomically thin (2-D) material possesses a naturally occurring circular rotation. [24] Topological effects, such as those found in crystals whose surfaces conduct electricity while their bulk does not, have been an exciting topic of physics research in recent years and were the subject of the 2016 Nobel Prize in physics. [23] A new technique developed by MIT researchers reveals the inner details of photonic crystals, synthetic materials whose exotic optical properties are the subject of widespread research. [22] In experiments at SLAC, intense laser light (red) shining through a magnesium oxide crystal excited the outermost " valence " electrons of oxygen atoms deep inside it. [21] LCLS works like an extraordinary strobe light: Its ultrabright X-rays take snapshots of materials with atomic resolution and capture motions as fast as a few femtoseconds, or millionths of a billionth of a second. For comparison, one femtosecond is to a second what seven minutes is to the age of the universe. [20] A 'nonlinear' effect that seemingly turns materials transparent is seen for the first time in X-rays at SLAC's LCLS. [19] Leiden physicists have manipulated light with large artificial atoms, so-called quantum dots. Before, this has only been accomplished with actual atoms. It is an important step toward light-based quantum technology. [18] In a tiny quantum prison, electrons behave quite differently as compared to their counterparts in free space. They can only occupy discrete energy levels, much like the electrons in an atom-for this reason, such electron prisons are often called "artificial atoms". [17] When two atoms are placed in a small chamber enclosed by mirrors, they can simultaneously absorb a single photon. [16] Category: Condensed Matter


Leiden physicists found a surprising interaction between electrons and a resist layer. The resist appears to charge and discharge due to incoming electrons. [19] By hitting electrons with an ultra-intense laser, researchers have revealed dynamics that go beyond 'classical' physics and hint at quantum effects. [18] The phenomenon of ionic wind has been known about for centuries: by applying a voltage to a pair of electrodes, electrons are stripped off nearby air molecules, and the ionized air collides with neutral air molecules as it moves from one electrode to the other. [17] A small group of physicists from the Israel Institute of Technology and the Institute for Pure and Applied Mathematics (IMPA) in Brazil have now come up with another method, showing it's theoretically possible to weave waves of light together in such a way that they stop dead in their tracks. [16] Researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences, together with collaborators from the Fu Foundation School of Engineering and Applied Science at Columbia University, have developed a system to convert one wavelength of light into another without the need to phase match. [15] Light, which travels at a speed of 300,000 km/sec in a vacuum, can be slowed down and even stopped completely by methods that involve trapping the light inside crystals or ultracold clouds of atoms. [14] A research team led by physicists at LMU Munich reports a significant advance in laser-driven particle acceleration. [13] And now, physicists at the) and their collaborators have demonstrated that computers are ready to tackle the universe's greatest mysteries. [12] The Nuclear Physics with Lattice Quantum Chromodynamics Collaboration (NPLQCD), under the umbrella of the U.S. Quantum Chromodynamics Collaboration, performed the first model-independent calculation of the rate for proton-proton fusion directly from the dynamics of quarks and gluons using numerical techniques. [11] Nuclear physicists are now poised to embark on a new journey of discovery into the fundamental building blocks of the nucleus of the atom. [10] The drop of plasma was created in the Large Hadron Collider (LHC). It is made up of two types of subatomic particles: quarks and gluons. Quarks are the building blocks of particles like protons and neutrons, while gluons are in charge of the strong interaction force between quarks. The new quark-gluon plasma is the hottest liquid that has ever been created in a laboratory at 4 trillion C (7 trillion F). Fitting for a plasma like the one at the birth of the universe. [9] Taking into account the Planck Distribution Law of the electromagnetic oscillators, we can explain the electron/proton mass rate and the Weak and Strong Interactions. Lattice QCD gives the same results as the diffraction patterns of the electromagnetic oscillators, explaining the color confinement and the asymptotic freedom of the Strong Interactions. Category: Condensed Matter


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