Non-invasive detection of charge-rearrangement in a quantum dot in high magnetic fields

We demonstrate electron redistribution caused by magnetic field on a single quantum dot measured by means of a quantum point contact as non-invasive detector. Our device which is fabricated by local anodic oxidation allows to control independently the quantum point contact and all tunnelling barriers of the quantum dot. Thus we are able to measure both the change of the quantum dot charge and also changes of the electron configuration at constant number of electrons on the quantum dot. We use these features to exploit the quantum dot in a high magnetic field where transport through the quantum dot displays the effects of Landau shells and spin blockade. We confirm the internal rearrangement of electrons as function of the magnetic field for a fixed number of electrons on the quantum dot.Comment: 4 pages, 5 figure

Infrared Jntensities of Liquids IV: Recent Measurements of Infrared Optical Constants and Absolute Infrared Absorption Intensities of Liquids by Multiple Attenuated Total Reflectance

Recent refinements are described to the CIRCLE, multiple attenuated total reflection method for measuring infrared optical and dielectric constants, absolute integrated intensities and, hence, molecular dipole derivatives. Attention is focussed on the accuracy of the method, which is estimated from measurements on H20 (1) and D20 (1).The real and imaginary optical constants agree with literature values to < 1.5% and about 6%, respectively, which is about the agreement of the literature values. The integrated areas agree with literature values to < 2%, and OH and OD bond dipole derivatives for H20 and D20 agree to < 10f0. pATR, refractive index, dielectric constant, and absorption cross section spectra are reported from 8000to 350 cm? for 2-butanol, and integrated absolute absorption intensities and bond dipole derivatives are presented for 2-butanol, 2-hexanol, and 2-octanol and compared with those for primary alcohols and water

Infrared Jntensities of Liquids IV: Recent Measurements of Infrared Optical Constants and Absolute Infrared Absorption Intensities of Liquids by Multiple Attenuated Total Reflectance

Recent refinements are described to the CIRCLE, multiple attenuated total reflection method for measuring infrared optical and dielectric constants, absolute integrated intensities and, hence, molecular dipole derivatives. Attention is focussed on the accuracy of the method, which is estimated from measurements on H20 (1) and D20 (1).The real and imaginary optical constants agree with literature values to < 1.5% and about 6%, respectively, which is about the agreement of the literature values. The integrated areas agree with literature values to < 2%, and OH and OD bond dipole derivatives for H20 and D20 agree to < 10f0. pATR, refractive index, dielectric constant, and absorption cross section spectra are reported from 8000to 350 cm? for 2-butanol, and integrated absolute absorption intensities and bond dipole derivatives are presented for 2-butanol, 2-hexanol, and 2-octanol and compared with those for primary alcohols and water

The Landscape of Identity Model:An Integration of Qualitative and Quantitative Aspects of Identity Development

The landscape of identity model views identity as a constellation of commitments with different levels of strength and integration, showing how this constellation emerges from everyday life experiences. Drawing on key principles from the complex dynamic systems approach, our model further describes this conceptualization, as well as the mechanisms underlying the development of an identity landscape. We show that the model solves current conceptual issues within identity theory, specifies how Marcia’s four identity statuses can be viewed as particular types of identity landscapes, and helps to further develop the identity field by generating predictions regarding how individuals with different types of identity landscapes would respond to major life events

Real-time laser ultrasonic monitoring of laser-induced thermal processes

Intra- and inter-layer integrity of components fabricated with advanced manufacturing techniques, such as laser powder bed fusion, is dependent upon rapid heating, melting, and solidification processes. There is a need for new techniques to provide in situ feedback of these processes. Here a laser-based ultrasonic technique to probe thermal effects induced by a high-power continuous wave laser in titanium samples is described. Numerical simulations were performed to show that, for a spatially uniform heating beam, laser-induced surface acoustic waves are strongly influenced by surface heating conditions, are dispersive in the case of rapid heating, and that an abrupt velocity reduction happens upon the onset of surface melting. Furthermore, laser-based ultrasound experimental results which monitor the transient change of surface wave travel time associated with high power laser surface heating are provided. A pulsed laser is used to generate high frequency surface acoustic waves that propagate through the laser-heated region and are detected using a photorefractive crystal-based interferometer. Qualitative agreement is observed between theory and experiment with both showing a rapid reduction in the surface wave velocity at the onset of illumination and further decrease in surface wave velocity associated with melting. It is demonstrated that changes in the surface wave velocity can be used to track local heating and detect the onset of surface melting in real time. &nbsp;</p

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Laser-controlled fluorescence in two-level systems

The ability to modify the character of fluorescent emission by a laser-controlled, optically nonlinear process has recently been shown theoretically feasible, and several possible applications have already been identified. In operation, a pulse of off-resonant probe laser beam, of sufficient intensity, is applied to a system exhibiting fluorescence, during the interval of excited- state decay following the initial excitation. The result is a rate of decay that can be controllably modified, the associated changes in fluorescence behavior affording new, chemically specific information. In this paper, a two-level emission model is employed in the further analysis of this all-optical process; the results should prove especially relevant to the analysis and imaging of physical systems employing fluorescent markers, these ranging from quantum dots to green fluorescence protein. Expressions are presented for the laser-controlled fluorescence anisotropy exhibited by samples in which the fluorophores are randomly oriented. It is also shown that, in systems with suitably configured electronic levels and symmetry properties, fluorescence emission can be produced from energy levels that would normally decay nonradiatively. © 2010 American Chemical Society

Far-field optical imaging and manipulation of individual spins with nanoscale resolution

A fundamental limit to existing optical techniques for measurementand manipulation of spin degrees of freedom is set by diffraction, which does not allow spins separated by less than about a quarter of a micrometre to be resolved using conventional far-field optics. Here, we report an efficient far-field optical technique that overcomes the limiting role of diffraction, allowing individual electronic spins to be detected, imaged and manipulated coherently with nanoscale resolution. The technique involves selective flipping of the orientation of individual spins, associated with nitrogen-vacancy centres in room-temperature diamond, using a focused beam of light with intensity vanishing at a controllable location, which enables simultaneous single-spin imaging and magnetometry at the nanoscale with considerably less power than conventional techniques. Furthermore, by inhibiting spin transitions away from the laser intensity null, selective coherent rotation of individual spins is realized. This technique can be extended to subnanometre dimensions, thus enabling applications in diverse areas ranging from quantum information science to bioimaging