Spectroscopy of low and intermediate Z elements at extreme conditions: in situ studies of Earth materials at pressure and temperature via X-ray Raman scattering

ABSTRACT

X-ray Raman scattering spectroscopy is an emerging method in the study of low and intermediate Z elements' core-electron excitations at extreme conditions in order to reveal information on local structure and electronic state of matter in situ. We discuss the capabilities of this method to address questions in Earth materials' science and demonstrate its sensitivity to detect changes in the oxidation state, electronic structure, coordination, and spin state. Examples are presented for the study of the oxygen K-, silicon L- and iron M-edges. We assess the application of both temperature and pressure in such investigations exploiting diamond anvil cells in combination with resistive or laser heating which is required to achieve realistic conditions of the Earth's crust, mantle, and core.     

Thermodynamics of relativistic quantum fields confined in cavities

We investigate the quantum thermodynamical properties of localised relativistic quantum fields, and how they can be used as quantum thermal machines. We study the efficiency and power of energy transfer between the classical gravitational degrees of freedom, such as the energy input due to the motion of boundaries or an impinging gravitational wave, and the excitations of a confined quantum field. We find that the efficiency of energy transfer depends dramatically on the input initial state of the system. Furthermore, we investigate the ability of the system to extract energy from a gravitational wave and store it in a battery. This process is inefficient in optical cavities but is significantly enhanced when employing trapped Bose Einstein condensates. We also employ standard fluctuation results to obtain the work probability distribution, which allows us to understand how the efficiency is related to the dissipation of work. Finally, we apply our techniques to a setup where an impinging gravitational wave excites the phononic modes of a Bose Einstein condensate. We find that, in this case, the percentage of energy transferred to the phonons approaches unity after a suitable amount of time. These results give a quantitative insight into the thermodynamic behaviour of relativistic quantum fields confined in cavities.     

Optical activity of incommensurate crystals with plane-wave modulation

A phenomenological approach is used to discuss the propagation of polarized light in the incommensurately modulated phases of crystals of the family A₂BX₄ with spatially averaged inversion symmetry. The Jones-matrix technique for an anisotropic inhomogeneous medium is used to calculate the optical parameters of a crystal with sinusoidally modulated dielectric parameters. It is demonstrated that these crystals can exhibit a weak optical activity, i.e., weaker than that of crystals without inversion symmetry. Also discussed are boundary conditions on the phase of the modulation wave at the surface of a crystal plate. Results are obtained suggesting that the optical properties of an incommensurately modulated crystal need not depend on the shape of the modulation wave. Fiz. Tverd. Tela (St. Petersburg) 39, 1360–1365 (August 1996)     

Branching behavior of field dynamics of resonators of left-handed materials

In this paper, we study the spatiotemporal dynamics of left-handed materials that contain nonlinear cavities. These materials, having a negative refractive index, exhibit a nonlinear electromagnetic behavior. The insertion of the left-handed material into an optical cavity results into a variety of branching behavior of optical oscillators that are degenerate. The optical Kerr cavity considered in this work contains a cubic nonlinearity. The objective of this work was to investigate how branching behavior can yield useful information about the relative amount of left-handed and right-handed material controlling the diffraction in cavity. We will apply the reductive perturbation method-based multi-equation bifurcation theory to a scalar nonlinear Schrodinger equation and show how period-doubling occurs during optical wave propagation.     

Photostimulated desorption studies on potassium iodide

Abstract

In this work we present the results of photostimulated desorption measurements obtained on KI under excitation in the fundamental absorption region. Yield curves of both potassium and iodine desorbed atoms are reported at several sample temperatures. We discuss the experimental results in terms of the optical constants and of the production efficiency of F and H centers in KI.     

Dark Equations

Abstract

Observing the Universe, astronomers have concluded that the motion of stars can not be accounted for unless one assumes that most of the mass in the Universe is carried on by a “dark matter”, so far impervious to all attempts at being detected. There is now a similar concept of “dark energy”. I shall discuss a different subject, “dark equations”. These have never indicated that they influence anything or even exist, but if one supposes that they do exist, one can systematically discover them and study their properties, some of which turn out to be strange and others mysterious. These equations are similar in spirit to what one gets when linearizing a given system, or studies how an external linear wave interacts with a particular solution of a given system. We define and study linear extensions of dynamical systems in general, and integrable and Hamiltonian systems in particular. Systems discussed include the KdV and mKdV equations and the associated Miura maps, the Burgers hierarchy and the associated Hopf–Cole transformations, long wave equations, the Benney hierarchy, and the KP hierarchy.     

Spectral scattering properties of a nanohole in a noble-metal film in the evanescent waves area

The effect of enhanced optical transmission through subwavelength holes and their arrays is used for multiple practical applications especially in optical antennas and local biosensors design. This effect is usually considered under excitation of plane wave propagating at the normal direction to the screen surface. In this work the effect of extreme transmission through the hole in the evanescent wave's area is in focus. The discrete sources method has been applied to analyse the spectral characteristics of light scattered by a cylindrical nanohole in a noble-metal film on a prism surface. The influence of the wavelength, incident angle, film materials and hole's filling on the scattering characteristics has been investigated. A close correlation between the effect of extreme transmission and the surface plasmon resonances has been detected.     

Designing of Optical Fiber Sensing Probe

Evanescent wave configuration has been extensively used in the development of fiber-optic sensor for different biomedical applications. In the present investigation we have theoretically proposed the designing of single-mode and multimode optical fiber sensing probes, which can be prepared by removing a few centimeters of cladding near the distal end of the step index optical fiber. In this theoretical study, we found that the removal of cladding causes V-number mismatching and this has led to the loss of signal acquisition from the sensing region. Therefore, to minimize these losses we have proposed to reduce the radius by step etch and tapering technique. It was found that step etching and tapering enhances the strength and penetration depth of the evanescent wave significantly.     

Tunneling through discrete levels in the continuum

We study the ballistic transport in quantum channels containing attractive impurities. We show that coherent interaction between asymptotic resonances may cause resonances to disappear and discrete levels to appear in the continuum at certain (critical) values of the parameters of the system. For the first time the tunneling of an electron through discrete levels is investigated. We find that the transmissivity changes dramatically when the scattered electrons at infinity have an energy coinciding with that of the discrete levels. It is found that a new type of degeneracy may arise in the system at critical values of the parameters, a degeneracy in which one state is described by a localized wave function and the other, by a propagating wave function. We calculate the critical values of the parameters of the structure and discuss ways of experimentally implementing this effect in two-dimensional channels. Zh. éksp. Teor. Fiz. 115, 211–230 (January 1999)     

On the partial wave method for self energy calculations for non-hydrogenic electrons

Abstract

A method for computing the self-energy correction for highly-ionized and high-Z many electron atoms is proposed and developed. The method is based on a partical wave analysis, and is immediately applicable to general potentials and many-electron wavefunctions.

In this work we discuss the general approach, develop a formalism amenable to practical anal- ysis, provide the angular momentum reduction for arbitrary one-electron orbitals, and describe the computation of the twdimensional integrals and their kernels required for the partial wave analysis. Analytical results allowing for a practical renormalization scheme are discussed.

This work is exploratory and developmental, and the present document provides a status report of our eforts. To date we have obtained numerical evidence that the method successfully handles the renormalization, and we report on significant progress in numerical methods for evaluating and approximating the two-dimensional integrals which occur in the method. We believe that this method can ultimately achieve an accuracy which is competitive with that of modern Brown's method calculations.

The methods discussed within this work for approximating the two-dimensional radial matrix eIements including the full retarded couIomb interaction can be applied to other relativistic atomic physics calculations as a practical way to obtain improvements over the coulomb and Breit approximations.     

All-reflective optical system design for extreme ultraviolet lithography

All-reflective optical systems,due to their material absorption and low refractive index,are used to create the most suitable devices in extreme ultraviolet lithography （EUVL）.In this letter,we present a design for an all-reflective lithographic projection lens.We also discuss its design idea and structural system.After analysis of the four-mirror optical system,the initial structural parameters are determined,the optical system is optimized,and the tolerances of the system are analyzed.We also show the implementation of optimal layout and desired imaging performance.     

关于Airy光束衍射及自加速性质的研究

对Airy光束的特性做进一步探讨, 一方面对无限宽Airy光束的重心问题给出新的理论说明, 另一方面着重对有限宽情形下的Airy光束的奇特性质进行探讨. 文中采用反证法给出无衍射的讨论, 同时结合数值模拟给出高斯函数及矩形函数限定下的有限宽Airy光束的场分布, 并由此得到其重心位置的轨迹: 重心位置是不变的, 不可能整体自由加速. 最终得到有限宽Airy光束既不可能在自由空间加速, 也不可能是无衍射光束. 关键词： Airy光束 无衍射 自加速 数值模拟     

Fabry-Perot cavity in the field of a gravitational wave

The structure of the electromagnetic field inside a laser cavity—a gravitational-wave detector—is studied. The properties of the spatial and temporal phases of the standing electromagnetic wave are discussed in detail and the corrections appearing in the electric field of the wave as a result of the action of gravitational radiation on the optical system are determined. Zh. éksp. Teor. Fiz. 113, 398–408 (February 1998)     

Bit-error rate for free-space optical communication with tip–tilt compensation

In this paper, a new kind of method is developed to analyse the bit-error rate for a free-space optical communication system, which is based on the three most important parameters of scintillation statistics, i.e. fraction of time of fade and surge, mean frequency of level crossings, and mean duration of fade and surge. By using this method, the relationship between the bit-error rate and scintillation is clearly identified. The tip–tilt error deteriorates the performance of a free-space optical communication system. Fine tracking ability of adaptive optics (through tip–tilt compensation) can overcome this difficulty. The fade and surge statistical parameters with tip–tilt compensation are evaluated for the plane wave model. The bit-error rate as a function of the scintillation statistical parameters (with tip–tilt compensation) is developed. The results show that the bit-error rate is reduced notably through tip–tilt compensation for free-space optical communication.     

A high-precision optical metrology system for determining the thickness of birefringent wave plates

This study develops a non-destructive measurement system for determining the thickness and refractive indices of birefringent optical wave plates. Compared to previous methods presented in the literature, the proposed metrology system provides the ability to measure the thickness of the birefringent optical plate in high-precision. The results show that for a commercially available birefringent optical wave plate with refractive indices of n_e=1.5518, n₀=1.5427 and a thickness of 452.1428 μm, the experimentally determined value for the error in the wave plate thickness measurement is just 0.046 μm. The measurement resolution of the proposed system exceeds that of the interferometer hardware itself. The proposed method provides a simple yet highly accurate means of measuring the principal optical parameters of birefringent glass wave plates.     

Elastic-plastic phenomena in ultrashort shock waves

A physical model of shock-wave phenomena in metals irradiated by a femtosecond laser pulse has been developed. The use of the experimental results (reported in S.I. Ashitkov et al., Pis’ma Zh. Eksp. Teor. Fiz. 92, 568 (2010) [JETP Lett. 92, 516 (2010)] together with the molecular dynamics simulation makes it possible to study the elastic properties of aluminum crystals at extreme shear stresses comparable in amplitude with the shear modulus. As a result, the elastic Hugoniot adiabat has been continued to the region of metastable elastic states at very high pressures, which are one or two orders of magnitude higher than the commonly accepted values for the dynamic elastic limit. It has been shown that the ultrashort elastic shock wave of superhigh pressure precedes the formation of the known split-shock wave structure consisting of an elastic precursor and a plastic shock wave.     

The near-field effect in a quantum computer

It is shown that in principle it is possible to write optical information on individual quasiresonant atoms in a concentrated system by changing the angle of incidence of an external light wave. Pis’ma Zh. éksp. Teor. Fiz. 69, No. 10, 750–754 (25 May 1999)     

On the problem of catastrophic relaxation in superfluid 3He-B

In this Letter, we discuss the parametric instability of the texture of homogeneous (in time) spin precession and explain how the spatial inhomogeneity of the texture may change the threshold of the instability in comparison with the idealized spatial homogeneous case considered in our JETP Letter 83, 530 (2006). This discussion is inspired by the critical comment of I.A. Fomin (JETP Lett., this issue) related to the above questions. In addition, we considered here the results of direct numerical solution of the full Leggett-Takagi equation of motion for magnetization in ³He-B and experimental data for the magnetic field dependence of the catastrophic relaxation that provide solid support for the theory of this phenomenon presented in our 2006 JETP Letter. The text was submitted by the authors in English.     

A simple study of the correlation effects in the superposition of waves of electric fields: The emergence of extreme events

In this paper, we study the effects of correlated random phases in the intensity of a superposition of N wavefields. Our results suggest that regardless of whether the phase distribution is continuous or discrete if they are random correlated variables, we will observe a denser tail distribution and the emergence of extreme events (amplitudes 30-40 times larger than their average) as the phases correlation increase. Recent results in the literature discuss the role of phase correlations on the emergence of rogue waves both in linear and nonlinear systems, but the mechanisms to generate them are not always straightforward. We show here a simple way to correlate the wavefield that makes it clear that rogue waves or denser tails appear mainly due to wave correlations instead of any particular system property.     

Two-level Atom in an Electromagnetic Wave of Circle Polarization

We study a two-level atom interacting with an electromagnetic wave of circle polarization, and work out the wave functions, the energy values and momentum values of the atom. PACS: 32.80.-t, 03.65.Ge