摘要:

Using one and the same simple variational principle for average energy, a new equation is obtained equivalent to the set of two equations: the time‐independent Schrödinger equation and that describing canonical Gibbs distribution.

ISSN:0002-9505    

DOI:10.1119/1.13540

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP

摘要:

An experimental illustration of the formation of a band structure in a solid is presented. It is based on the structure analysis of the x‐ray excited photoelectron valence band spectra recorded for a series of molecules with increasing length, the linear normal‐alkanes (CnH2n+2, where 1≤n≤∞). This experiment shows how a single atomic carbon 2selectronic level evolves to molecular orbitals, and then to a band, as the numbernof carbon atoms increases in the molecule and simulates at the end a 1‐D solid. It is thought that such a simple picture might help to understand and illustrate a solid state physics course about band structures.

ISSN:0002-9505    

DOI:10.1119/1.13541

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP

摘要:

A wave tank experiment (first described by the nineteenth‐century engineer and naval architect John Scott Russell) relates a linear eigenvalue problem from elementary quantum mechanics to a striking feature of modern nonlinear wave theory: multiple generation of solitons. The tank experiment is intended for lecture demonstrations.

ISSN:0002-9505    

DOI:10.1119/1.13542

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP

摘要:

We describe a Monte Carlo simulation of self‐catalysis of orthohydrogen molecules in solid hydrogen in one‐ and two‐dimensional lattices at low temperatures in the absence of molecular diffusion. The problem is useful for illustrating the importance of lattice geometry and near neighbor relationships in such calculations. The simulations were performed on a small computer and may be of use in teaching Monte Carlo techniques.

ISSN:0002-9505    

DOI:10.1119/1.13543

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP

摘要:

A detailed discussion of electric energy storage in the presence of dielectrics is presented. The discussion is general and is aimed at the introductory–intermediate levels, when an integral representation of the laws of electrostatics is more familiar to the student. The case where a discrete set of point charges is slowly transported into the vicinity of an arbitrary dielectric is first considered and then an extension to the continuous distribution is presented. A simple model of atomic polarization is introduced and used to illustrate dielectric nonlinearities and the concept of self‐interaction. It is shown that the energy densityE⋅D/2 is restricted to the case of linear dielectrics and a novel way of introducing Maxwell’s displacement current term at a more advanced level is suggested as a natural extension of the electrostatic case.

ISSN:0002-9505    

DOI:10.1119/1.13544

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP

摘要:

Using Green’s function techniques a time‐dependent theory of α decay in the standard one‐body model is developed. Formulas are obtained for the decay rate and α energy. These formulas are combined with experimental information to show that to a good approximation theinitialα‐particle wave function vanishes on or near the nuclear surface.

ISSN:0002-9505    

DOI:10.1119/1.13545

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP

摘要:

This paper describes an experiment relating to the diffusion of charge carriers in homogeneous semiconductor material. Diffusion theory, as outlined in this paper, is applied to deduce from measurements a quantity called the bulk lifetime of excess minority carriers: a quantity which is independent of the size, shape, and surface condition of the semiconductor sample. Because of this independence, the bulk lifetime is used as one of the characterizing quantities of semiconductor material. In performing this experiment, the student will gain a working knowledge of diffusion theory as applied to semiconductor carriers, and at the same time become acquainted with an important technique for the characterization of semiconductor material. The actual duration of involvement will depend upon the amount of setting up of equipment, sample preparation, etc., that is expected of the student. An oscilloscope of fast rise time (200–MHz bandwidth), and a xenon flash tube with pulse duration of a few microseconds (General Radio 1542‐B electronic stroboscope is a proven possibility), are the major items of equipment needed.

ISSN:0002-9505    

DOI:10.1119/1.13522

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP

摘要:

A recursion equation for computing the total reflectance amplitude from a given potential is derived. It is shown that the poles of the total reflectance amplitude are the bound eigenvalues of the problems. The method avoids complicated boundary value problems usually encountered in computing the bound eigenvalues of the Schrödinger equation. The utility of the method is demonstrated by two examples. A simple algorithm for the numerical approach is derived. Finally the physical meaning in terms of standing waves is discussed.

ISSN:0002-9505    

DOI:10.1119/1.13523

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.13524

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.13525

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP