杰出的导师亥姆霍兹及其对维恩的影响

文章在简要介绍著名物理学家亥姆霍兹在生平及科学贡献的基础上，着重讨论了亥姆霍兹作为一位杰出的导师，对维恩的一生产生了决定性的影响。     

Combined cylindrical mass analyzers

We report on the results of theoretical analysis and numerical calculation of two new mass analyzers: a hybrid analyzer, which is a contiguous combination of the Hughes-Rozhansky energy analyzer and the Wien velocity filter with superimposed sector uniform magnetic and radial electric fields, and a device formed by a combination of a cylindrical deflector and a sector Wien filter with uniform electric and radial magnetic field.     

Microscopic aspects implied by the Second Law

It is conventional to try to arrive at the Boltzmann principle and the Second Law starting with the laws of dynamics at the microscopic level. In this article the opposite view is presented: Starting with the Second Law, microscopic properties are derived. A classical result of Wien is developed into a general theorem, and the possibility of deriving the Boltzmann principle as a consequence of Carnot's theorem is discussed.     

Nonlinear ion transport in liquid and solid electrolytes

This paper describes nonlinear ion transport properties of liquid and solid electrolytes. Typically, the relation between ionic current density and electric field becomes nonlinear at electric fields above 50–100?kV/cm. We review the 1st and 2nd Wien effect found in classical strong and weak electrolyte solutions as well as the strong nonlinear ion transport effects observed for inorganic glasses and for polymer electrolytes. Furthermore, we give an overview over models describing nonlinear ion transport in electrolyte solutions, in glasses and in polymers. Recent results are presented for the nonlinear ionic conductivity of supercooled ionic liquids. We show that supercooled ionic liquids exhibit anomalous Wien effects, which are clearly distinct from the classical Wien effects. We also discuss the frequency dependence of higher-order conductivity and permittivity spectra of these liquids.     

Spin-to-orbital angular momentum conversion and spin-polarization filtering in electron beams

We propose the design of a space-variant Wien filter for electron beams that induces a spin half-turn and converts the corresponding spin angular momentum variation into orbital angular momentum of the beam itself by exploiting a geometrical phase arising in the spin manipulation. When applied to a spatially coherent input spin-polarized electron beam, such a device can generate an electron vortex beam, carrying orbital angular momentum. When applied to an unpolarized input beam, the proposed device, in combination with a suitable diffraction element, can act as a very effective spin-polarization filter. The same approach can also be applied to neutron or atom beams.     

Underlying probability distributions of Planck's radiation law

The derivation of Planck's radiation law can be considered as a transformation of a thermodynamic relation for black-body radiation into a fundamental relation in which the error law is the negative binomial distribution. In both limiting frequency ranges it transforms into Poisson distributions; in the Wien limit, it is the distribution of the number of photons, whose most probable value is given by Boltzmann's expression, while in the Rayleigh-Jeans limit, it is the distribution of the number of Planck oscillators. In the general case, they are Bernoullian random variables. In the Rayleigh-Jeans limit, the probability of determining the number of oscillators in a given frequency interval for a fixed value of the energy can be inverted to determining the probability of the energy for a fixed number of oscillators. The probability density is that of the canonical ensemble.     

An exact expression for the Wien displacement constant

A rapidly converging, closed-form series is presented for the Wien displacement constant.     

An exact expression for the Wien displacement constant

A closed-form result for the Wien displacement constant is reported.     

一种推导文氏桥电路振荡条件的新方法

提出把文氏桥电路等效成负阻振荡器的新观点，从而利用物理概念导出了该电路的振荡条件和振荡频率公式，并将结果与传统理论进行了比较。     

Energieverluste monochromatisierter 30 keV-Lithiumionen an Argon und Äthylen

The energy loss spectra of 30-keV Li₇ ⁺ ions after interaction with argon and ethylene have been studied. Wien filters were used as monochromator and energy analyzer, an energy resolution of 0.2 eV was achieved. The ion energy loss spectra obtained differ from those taken with electrons at the same primary energy mainly in two points: In the ion spectra energy losses are found with strong intensities corresponding to optically forbidden transitions which are not excited by fast electrons. Furthermore in the energy range beyond the first ionization limit energy losses appear which are due to charge transfer into excited states of the lithium atom and re-ionization.     

Energy bands and electron densities of Li3N

Self-consistent band-structure calculations on the fast ionic conductor lithium nitride are performed by means of the linearized augmented plane wave (LAPW) method within the local density formalism. The corresponding density of states is decomposed into local (inside spheres), partial (l-like) and symmetry (p _x p _y ;p _z ) components from which an only very small covalent contribution to the bonding in Li₃N can be deduced. Electron density maps reveal Li₃N to be highly ionic (near Li⁺ and N^3–). A simple Watson model, although a good first approximation, cannot account for all details. For instance a remarkable non-spherical electrons density is found around N which may explain the high electric field gradient experimentally observed on this site; furthermore a reduced electron density around the Li-sites appears in contrast to a simple supper-possition of N^3– ionic densities. However, calculated x-ray structure factors and difference electron densities are in good qualitative agreement with recent x-ray diffraction experiments.This work has been supported by the Hochschuljubiläumsstiftung der Stadt Wien. All calculations were carried out at the Rechenzentrum der Technischen Universität Wien     

Ein modifiziertes Wiensches Filter als Elektronenmonochromator

A velocity selector of the Wien type (crossed uniform electric and magnetic fields) obtains the property of stigmatic focusing by replacing the uniform electric field by a field with cylindrical curvature. Focusing conditions, energy dispersion, and the apertural error are calculated. A monochromator of this type is constructed for electrons of 100 eV energy. With an exit aperture of 50 μ diameter an energy spread of 0,06 eV was measured.     

Thermodynamics of Blackbody Radiation Via Classical Physics for Arbitrarily Shaped Cavities with Perfectly Conducting Walls

An analysis is carried out involving reversible thermodynamic operations on arbitrarily shaped small cavities in perfectly conducting material. These operations consist of quasistatic deformations and displacements of cavity walls and objects within the cavity. This analysis necessarily involves the consideration of Casimir-like forces. Typically, even for the simplest of geometrical structures, such calculations become quite complex, as they need to take into account changes in singular quantities. Much of this complexity is reduced significantly here by working directly with the change in electromagnetic fields as a result of the deformation and displacement changes. A key result of this work is the derivation that for such cavity structures, classical electromagnetic zero-point radiation is the appropriate spectrum at a temperature of absolute zero to ensure that the reversible deformation operations obey both isothermal and adiabatic conditions. In addition, a generalized Wien displacement law is obtained from the demand that the change in entropy of the radiation in these arbitrarily shaped structures must be a state function of temperature and frequency.     

Practical aspects of running the WIEN2k code for electron spectroscopy

The Wien2k code is widely used for the calculation of electron energy loss spectra. Low loss spectra can be calculated with the OPTIC package while core loss spectra are calculated with the TELNES program. A new version, TELNES.2, takes into account the effects of relativity for anisotropic materials. In this paper we discuss the effects of different parameters used for the self-consistent calculation of the electron density on the obtained spectra. We give an overview of possibilities for the calculation of complicated systems requiring a super-cell, like defects or disordered systems. We discuss the problem of the core hole and of the calculation of orientation-sensitive spectra and give an overview of results already published.     

Development of in-lab energy-filtered X-ray photoemission electron microscope using air-core-coil-type multipole Wien filter

We have developed an in-lab energy-filtered X-ray photoemission electron microscopy (EXPEEM) combining a high-brilliance X-ray source and a new Wien filter-type energy analyzer, which can accept photoelectrons in a wide angle. To obtain high energy resolution, we enlarged the inner diameter of the filter and reduced aberrations of an analyzer using multipole electrodes and air-core coils. We obtained an energy-filtered image of photoelectrons.     

Using spectral distribution of radiance temperature and relative emissivity for determination of the true temperature of opaque materials

A method for determining the thermodynamic (true) temperature of opaque materials by the registered spectrum of thermal radiation under the conditions when we do not know emissivity of a free-radiating body is presented. A special function, which is a product of relative emissivity of tungsten by the radiation wavelength, was used as the input data. The accuracy of results is analyzed. It is shown that when using relative emissivity, the proposed algorithm can be used both within the range of applicability of the Wien approximation and the Planck formula.     

Das Auflösungsvermögen des elektrostatisch-magnetischen Energieanalysators für schnelle Elektronen

The electrostatic magnetic energy analyzer consists of a Wien filter (crossed electric and magnetic fields) between two immersion lenses. The energetic resolution of the analyzer is calculated. The intensity problem in connection with the generation of a monoenergetic electron beam is discussed considering anomalous energy spread in high density beams. With an arrangement containing two analyzers of the same kind the resolving power is experimentally determined to 0.017 ev.     

Radiation of a quantized black hole

The maximum entropy of a quantized surface is demonstrated to be proportional to the surface area in the classical limit. The general structure of the horizon spectrum and the value of the Barbero-Immirzi parameter are found. The discrete spectrum of thermal radiation of a black hole naturally fits the Wien profile. The natural widths of the lines are very small as compared to the distances between them. The total intensity of the thermal radiation is calculated.     

Physicists and Physics in Munich

We give a tour of Munich and some outlying sites that focuses on the lives and work of the most prominent physicists who lived in the city, Count Rumford, Joseph Fraunhofer, Georg Simon Ohm, Max Planck, Ludwig Boltzmann, Albert Einstein, Wilhelm Conrad Röntgen, Wilhelm Wien, Arnold Sommerfeld, Max von Laue, and Werner Heisenberg. We close with a self-guided tour that describes how to reach these sites in Munich.     

New low-energy RIB separator CRIB for nuclear astrophysics

An in-flight RIB separator at low energies, which is the first extensive separator at low energies, called CRIB, is just under construction at CNS. This consists of a double-achromatic magnetic separator, a window-less gas target, and a Wien filter. Some characteristics of the CRIB are described. Possible experimental plans are also discussed in our nuclear astrophysics project for the study of the explosive hydrogen burning process, especially on the onset mechanism. Received: 1 May 2001 / Accepted: 4 December 2001