WWW Dissemination of Information
INTENDED OUTCOME AND
BACKGROUND
The Office of Electronic Commerce in Scientific and Engineering Data (ECSED) is
responsible for the Physics Laboratory (PL) world wide web (WWW) pages at
physics.nist.gov. We produce material for WWW publication, encourage and
support the production of material by others, and ensure the high quality of
disseminated information. We are also engaged with PL Divisions and the NIST
Standard Reference Data Program in developing physical reference databases for
WWW dissemination. We design and develop effective WWW database interfaces to
facilitate access to the data.
Since June 1994, we have provided a wide array of information ranging from
physical reference data, technical activities, research and calibration
facilities, technical contacts, publication lists, general interest, and news
items. In a recent month (October 2002), there were nearly one million
requests for web pages from the Gaithersburg server (nearly half from our
~ 25 online databases),
and nearly 8.8 million requests for web pages from all PL web servers
(including http://www.time.gov and
http://tf.nist.gov).
There are many new web databases currently under development, including:
- Handbook of Basic Atomic Spectroscopic Data,
- Spectral Data for the Chandra X-ray Observatory,
- X-ray Transition Energies Database,
- Chemical Agents Database,
- Potentials of Alkaline-Earth Dimers,
- Amorphous Metals Database, and
- Hydrogen and Deuterium Energies and Transition Frequencies (an interactive
website).
Accomplishments
Units Markup Language
We have continued a collaboration with Lawrence Berkeley National Laboratory
and NIST's Electronics and Electrical Engineering Laboratory to develop an XML
(eXtensible Markup Language) schema for encoding scientific measurement units.
Adoption of this schema will allow for the unambiguous exchange of numerical
data over the Internet.
We are in the process of creating an international working group to examine and
discuss the completed first draft of the UnitsML schema. In addition, we have
begun collaborating with the NIST Information Technology Laboratory to
establish a NIST registry containing SI and non-SI unit information and to
create an XML registry containing the UnitsML schema. We anticipate this
registry will be used by our customers to download industry-specific
dictionaries of scientific units.
Molecular Spectroscopy Tutorials On-Line
We collaborated with the Optical Technology Division to make available on the
WWW two popular tutorials in molecular spectroscopy. The original documents
were converted to HTML, and the equations were formatted as both images and
LaTeX to ensure their wide accessibility.
The first of these documents is the extensively cited NBS Monograph 115, The Calculation of Rotational Energy Levels and
Rotational Line Intensities in Diatomic Molecules. It played a major
role in standardizing the complex conventions and nomenclature used to describe
the quantum-mechanical behavior of diatomic molecules.
The document describes the derivation of the intensities of the spectral lines,
and contains a clear discussion of the rotational Hamiltonian and its symmetry
properties, necessary for calculating molecular energy levels. This pedagogical
monograph is of interest to the wide community of scientists dependent on
molecular spectroscopy for their success, including atmospheric and planetary
scientists, astronomers, plasma physicists, and analytical chemists. It is the
accepted, more rigorous companion to the popular textbook, Spectra of
Diatomic Molecules, written by the late Nobel Laureate Gerhard Herzberg.
The second tutorial newly offered online is Methane
Symmetry Operations. It was initially written in response to the needs
of chemists and physicists for conventions and guidance in working with the
complex mathematics involved in calculating the rotational energies and
intensities of tetrahedral molecules, such as methane and carbon tetrachloride.
Scientists interested in atmospheric sensing, combustion diagnostics, and
climate change will benefit from ready access to this document.
Molecular Databases On-Line
We collaborated with the Optical Technology Division to make available on the
WWW three linked databases of the microwave and RF spectra of diatomic,
triatomic, and hydrocarbon molecules. Originally published as spectral tables
in the Journal of Physical and Chemical Reference Data, the on-line version
includes additional molecules and allows advanced browsing and searching of the
data - by molecular species, type, or frequency.
Rotational spectral lines for 121 diatomic molecules, 55 triatomic
molecules, and 91 hydrocarbon molecules are included. The isotopic
molecular species, assigned quantum numbers, observed frequency, estimated
measurement uncertainty, and reference are given for each transition. The
spectral lines for many molecules and normal isotopic species have been refit
to produce a comprehensive and consistent analysis of all the data obtained
from many sources. The derived molecular properties, such as rotational and
centrifugal distortion constants, hyperfine structure constants, electric
dipole moments, rotational g-factors, and internuclear distances (for diatomic
molecules) are listed with one-standard-deviation uncertainties for all species.
Figure 1. Screen capture of a browser window for the "Molecular Spectral Databases" main web page.
The Diatomic, Triatomic, and Hydrocarbon Spectral Databases can be accessed on
the WWW at http://physics.nist.gov/MWtables. Further
information on additional molecular spectroscopic databases developed by the
Office of ECSED is available at http://physics.nist.gov/data.
Development of these databases was supported in part by NIST's Standard Reference Data (SRD) Group and by
NIST's Systems Integration for Manufacturing
Applications (SIMA) program.
"Technical Activities 2002" - Table of Contents |
