摘要:

A review is given of the latest Committee on Data for Science and Technology (CODATA) adjustment of the values of the fundamental constants. The new set of constants, referred to as the 1998 values, replaces the values recommended for international use by CODATA in 1986. The values of the constants, and particularly the Rydberg constant, are of relevance to the calculation of precise atomic spectra. The standard uncertainty (estimated standard deviation) of the new recommended value of the Rydberg constant, which is based on precision frequency metrology and a detailed analysis of the theory, is approximately 1/160 times the uncertainty of the 1986 value. The new set of recommended values as well as a searchable bibliographic database that gives citations to the relevant literature is available on the World Wide Web at physics.nist.gov/constants and physics.nist.gov/constantsbib, respectively. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1336265

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

The low pressure plasma processing environment is complex and presents many diagnostic challenges. Here the diagnostic techniques used for accurate and detailed measurement of the density and energy distributions of charged and neutral species are reviewed. Most of the techniques rely heavily on atomic and molecular data. The specific data needs of each diagnostic are outlined. It is shown that in total these data needs are vast and diverse and cannot all be met from specific measurements or calculations. The real need is for generic scaling rules for each of the significant atomic and molecular processes. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1336266

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Heavy-ion radiotherapy using high-energy carbon beams has been performed at the National Institute of Radiological Sciences, Japan. The physical frame works for heavy-ion radiotherapy are established using physical understandings of radiation physics. In order to increase the accuracy of heavy-ion radiotherapy, many physical problems should be solved. Unsolved problems, such as the depth dose distributions, range of heavy-ion in patients and heavy-ion dosimetry in the radiation therapy, are discussed. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1336267

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

There are now very comprehensive computer models for the steady state operation of most lamp types of commercial importance. For historical reasons associated with computer power and availability of data most of these models arrived too late to assist the design of radically new lamp types, but they do provide excellent understanding of lamp operation. In the last decade models have often played a key role in lamp development. In the case of fluorescent lamps the collisional-radiative models are very complete, but accuracy still needs to be improved to turn them in to computer-aided design models for new lamp variants. The key to this is to improve the data, especially for ionization processes. In the case of high-pressure (HP) alkali arcs there has been remarkable success in calculating realistic spectra based on molecular energy levels. For HP metal-halide lamps energy balance models are very sophisticated but the data for calculating the radiation are far from adequate; semi-empirical treatment of radiation looks more hopeful. We are now entering an era in which computer power is adequate andcalculatedsets of self-consistent data for collision cross-sections will soon be available even for atoms with many electrons. Similarly good quality molecular energy levels and transition dipole moments for dimers containing heavy atoms look well within reach. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1336268

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

A modeling network has been developed for Ar glow discharges with Cu cathode, consisting of several submodels, i.e., Monte Carlo simulations, fluid approaches and collisional-radiative models. The plasma species described in the models, include the electrons, Ar atoms, Ar ions, fast Ar atoms, Ar atoms in various excited levels, sputtered Cu atoms and Cu ions, both in the ground state and in various excited levels. In this paper, the models are described, and the various input data needed for the calculations are discussed. Typical results of the models include the electrical characteristics, the potential and electric field distribution, the densities, fluxes and energies of the various plasma species, information about collision processes in the plasma and about sputtering at the cathode, optical emission intensities, etc. Some of these results will be presented here, to illustrate the possibilities of the model. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1336269

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Charge exchange process for medium energy He ions backscattered from solid surfaces was studied using a high-resolution toroidal electrostatic analyzer(&Dgr;E/E=9×10−4).He ions backscattered from topmost atoms have a high fraction of nonqeuilibrium singly-ionized charge state and thus it generates a surface peak in the backscattering spectrum from an amorphous solid. The height and width of the surface peak provide the information about the electron capture and loss cross sections together with the ion-surface interaction region expanded from the top atomic plane toward the vacuum side. Dependence of the surface peak profile upon energy, exit-angle and materials of the surface is discussed in detail in the context of the ion-surface interactions. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1336270

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Molecules have been detected in interstellar and circumstellar clouds for over 60 years, but it has been only in the past 20 years or so that a significant effort has gone into chemical kinetic modelling of the processes by which they are formed and destroyed. In this paper, I review the physical conditions in the regions in which molecules are detected, and indicate the nature of the data required for a full interpretation of the observations. In particular, I describe the database for astrochemistry we have developed at UMIST, indicating areas for future development. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1336271

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

The history and development of the HITRAN molecular spectroscopic database is described. HITRAN was created as a compilation of spectroscopic parameters that could serve to provide the basic information to computer programs modeling atmospheric attenuation due to molecular gaseous absorption in the infrared. The first edition of the HITRAN database evolved from monographs on prominent bands of water vapor and carbon dioxide published by the National Bureau of Standards published in the 1960s. This first edition contained a limited set of parameters for bands of the seven most active infrared absorbers in the terrestrial atmosphere. HITRAN has since expanded to cover a broad spectral range from the millimeter through ultraviolet regions, to include absorption cross sections in addition to the discrete line transitions, to include information on about 60 different molecular species, to include more parameters for sophisticated remote-sensing retrieval programs, and has employed newer distribution methods. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1336272

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Progress continues on the development of databases for spectral properties of atoms and ions. Version 2.0 of the NIST Atomic Spectra Database (ASD) became available on the World Wide Web in March 1999. This version contains data for many more spectra than version 1.2, which it replaced, and the web interface is much more flexible in terms of presentation options for the user. We are now working to further improve the user interface, especially concerning ease of access to the references. The next version will provide hyperlinks from the spectrum page to references for the wavelengths and transition probabilities of that spectrum. As a continuing effort we are working to expand the coverage of spectra. The NIST Bibliographic Database on Atomic Transition Probabilities has been updated recently, and the NIST Bibliographic Database on Atomic Spectral Line Broadening will be updated sometime during 2000. Some uses of the databases for wavelength calibration of VUV lasers, online modeling of plasmas, and searches for the transition probabilities for all downward branches to specific energy levels of a particular atom for plasma diagnostics will be described. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1336273

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

The main objective of the Atomic and Molecular Data Unit of the International Atomic Energy Agency is to collect, assess, and make available a variety of data relevant to magnetic fusion energy and other nuclear energy applications. In this paper we present the methods by which the Unit achieves this goal. We also indicate the scope of the resulting databases and present a summary of the method for accessing the databases through the world-wide-web. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1336274

出版商:AIP    

年代:1900

数据来源: AIP