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Database Information
Atomic Spectroscopic Data
Atomic Spectra Database-Lines ASD Lines [help]
The lines database contains spectral lines and associated energy levels displayed in wavelength order with all selected spectra intermixed or in multiplet order. Transition probabilities for the lines are also displayed where available.
Atomic Spectra Database-Levels ASD Levels [help]
The levels database contains energy levels of a particular atom or ion displayed in order of energy above the ground state.

Ground States & Ionization Levels Ground States and Ionization Energies [help]
This form provides access to NIST critically evaluated data on ground states and ionization energies of atoms and atomic ions.

Handbook of Basic Atomic Spectroscopic Data Handbook of Basic Atomic Spectroscopic Data
This handbook is designed to provide a selection of the most important and frequently used atomic spectroscopic data in an easily accessible format. The compilation includes data for the neutral and singly-ionized atoms of all elements hydrogen through einsteinium (Z = 1-99). The wavelengths, intensities, and spectrum assignments are given in a table for each element, and the resulting total of some 12,000 lines for all elements are also collected into a single table, sorted by wavelength (a "finding list").
Energy Levels of Hydrogen and Deuterium Energy Levels of Hydrogen and Deuterium
This database provides theoretical values of energy levels of hydrogen and deuterium for principle quantum numbers n = 1 to 200 and all allowed orbital angular momenta l and total angular momenta j. The values are based on current knowledge of the relevant theoretical contributions including relativistic, quantum electrodynamic, recoil, and nuclear size effects. This interactive database allows a user to obtain individual energy levels and transition frequencies as well as tables of frequencies. Given the volume of the possible data, this Web site is designed to calculate the values as requested.
X-Ray Transition Energies Database X-Ray Transition Energies Database
This X-ray transition table provides the energies and wavelengths for the K and L transitions connecting energy levels having principal quantum numbers n = 1, 2, 3, and 4. The elements covered include Z = 10, neon to Z = 100, fermium. There are two unique features of this database: (1) all experimental values are on a scale consistent with the International System of measurement (the SI) and the numerical values are determined using constants from the most recent Recommended Values of the Fundamental Physical Constants: 1998 and (2) accurate theoretical estimates are included for all transitions.
Platinum Spectrum Spectrum of Platinum
An atlas of the spectrum of a platinum/neon hollow-cathode reference lamp in the region 1130 Å to 4330 Å is given, with the spectral lines marked and their intensities, wavelengths, and classifications listed. Graphical figures of the spectrum are included.
Spectrum of Th-Ar Hollow Cathode Lamps Spectrum of Th-Ar Hollow Cathode Lamps
This atlas presents observations of the infra-red (IR) spectrum of a low current Th-Ar hollow cathode lamp with the 2-m Fourier transform spectrometer (FTS) at NIST.
Atomic and Molecular Data
Electron Impact Cross Sections Electron-Impact Cross Sections
This is a database primarily of total ionization cross sections of molecules by electron impact. The database also includes cross sections for a small number of atoms and energy distributions of ejected electrons for H, He, and H2. The cross sections were calculated using the Binary-Encounter-Bethe (BEB) model, which combines the Mott cross section with the high-incident energy behavior of the Bethe cross section. Selected experimental data are included. Electron-impact excitation cross sections are also included for some selected atoms.
Potential Energy Surface Database Potential Energy Surface Database of Group II Dimer Molecules
The purpose of this work is to provide critical atomic and molecular data needed in order to evaluate the feasibility of using laser cooled and trapped Group II atomic species (Mg, Ca, Sr, and Ba) for ultra-precise optical clocks or quantum information processing devices.
Bibliographic Databases on Atomic Spectroscopy
Atomic Transition Probability Bibliographic Database Atomic Transition Probability Bibliographic Database
This interactive database contains references on atomic transition probabilities (oscillator strengths, line strengths, and radiative lifetimes). Both theoretical and experimental papers are listed.
Atomic Spectral Line Broadening Bibliographic Database Atomic Spectral Line Broadening Bibliographic Database
This interactive database contains references on atomic spectral line broadening (line shapes and shifts). Both theoretical and experimental papers are listed.
Atomic Energy Levels and Spectra Bibliographic Database Atomic Energy Levels and Spectra Bibliographic Database
This interactive database contains references on atomic energy levels and wavelengths. Preference is given to experimental papers.
X-Ray and Gamma Ray Data
Please visit the note on the X-Ray Attenuation Databases.
X-Ray Attenuation and Absorption X-ray Attenuation and Absorption for Materials of Dosimetric Interest
Tables and graphs of computed photon mass attenuation coefficients and mass energy-absorption coefficients from 1 keV to 20 MeV are presented for all of the elements (Z = 1 to 92) and for 48 compounds and mixtures of radiological interest. These coefficients are basic quantities used in calculations of the penetration and the energy deposition by photons (x-ray, gamma-ray, bremsstrahlung) in biological, shielding, and other materials.
Photon Cross Sections XCOM: Photon Cross Sections Database
This database can be used to calculate photon cross sections for scattering, photoelectric absorption and pair production, as well as total attenuation coefficients, in any element, compound or mixture, at energies from 1 keV to 100 GeV.
X-Ray Form Factor, Attenuation, and Scattering Form Factor, Attenuation, and Scattering Tabulation
The primary interactions of x-rays with isolated atoms from Z = 1 (hydrogen) to Z = 92 (uranium) are described and computed within a self-consistent Dirac-Hartree-Fock framework. The results are provided over the energy range from either 1 eV or 10 eV to 433 keV, depending on the atom. Self-consistent values of the f1 and f2 components of the atomic scattering factors are tabulated, together with the photoelectric attenuation coefficient for the atom, µ, and the value for the K-shell, µK, as functions of energy and wavelength.
Radiation Dosimetry Data
The databases ESTAR, PSTAR, and ASTAR calculate stopping-power and range tables for electrons, protons, or helium ions, according to methods described in ICRU Reports 37 and 49. Stopping-power and range tables can be calculated for electrons in any user-specified material and for protons and helium ions in 74 materials.
Stopping Power and Ranges for Electrons Electrons
Stopping Power and Ranges for Helium Ions Helium Ions
Stopping Power and Ranges for Protons Protons
Nuclear Physics Data
Radionuclide Half Lives Radionuclide Half-Life Measurements
This database is a table of the half lives of 61 important radionuclides measured primarily with ionization chambers by the Radioactivity Group of NIST. The included half lives range from 10 minutes to 60.7 years.
Atomic Weights and Isotopic Compositions Isotopic Compositions
This database contains the isotopic compositions or abundances of those elements which have characteristic terrestrial compositions. Atomic weights are also available for elements 1 through 111.
Condensed Matter Physics Data
Atom Ref Data for Electronic Structure Calcs Atomic Reference Data for Electronic Structure Calculations
This database consists of evaluated data for use in total-energy calculations of electronic structure by density-functional theory. It contains total energies and orbital eigenvalues for the atoms hydrogen through uranium, as computed in several standard variants of density-functional theory.

Information about the Ground-State, Ionization Energy, & Atomic Weight Data

Atomic Weights are based upon 12C. The values in parentheses, following the last significant digit to which they are attributed, are uncertainties.

For several of these elements, the standard atomic weight is given as an atomic-weight interval with the symbol [a, b] to denote the lower and upper bounds a and b of the relative atomic weight Ar of the element E as observed in different samples of normal materials; thus, [aAr(E) ≤ b].

Brackets [ ] enclosing a single value indicate the mass number of the most stable isotope. For radioactive elements with atomic numbers 95 or greater, the mass number of the most stable isotope is not specified, as the list of studied isotopes is still incomplete.

The ground-state and ionization data come from Ground Levels and Ionization Energies for the Neutral Atoms, which now retrieves data from the Ground States & Ionization Energies portion of the Atomic Spectra Database. Bibliographic references for the data can be found within the database.

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