This database provides access and search capability for NIST critically evaluated data on atomic energy levels, wavelengths, and transition probabilities that are reasonably up-to-date. The Atomic Spectroscopy Data Center has carried out these critical compilations. The Data Center is located in the Physical Measurement Laboratory at the National Institute of Standards and Technology (NIST).

This handbook provides a selection of the most important and frequently used atomic spectroscopic data in an easily accessible format. The compilation includes energy levels, ionization energies, wavelengths, line intensities, transition probabilities, and spectrum assignments for the neutral and singly-ionized atoms of all elements hydrogen through einsteinium (Z = 1-99), given in separate tables for each element. It includes approximately 12,000 spectral lines of all elements. Bibliographic references are provided for all data.

References contained in this database are from Bibliography on Atomic Energy Levels and Spectra, NBS Special Publication 363 and Supplements, as well as current references since the last published bibliography collected by the NIST Atomic Spectroscopy Data Center (http://www.nist.gov/physlab/div842/grp01/asdc_info.cfm). These references pertain to atomic structure and spectra that arise from interactions or excitations involving electrons in the outer shells of free atoms and atomic ions, or from inner shell excitations corresponding to frequencies up to the soft x-ray range. Please note that this database does not contain references to atomic transition probabilities, line intensities, or broadening. These references can be found in two other bibliographic databases maintained by the same Data Center: NIST Atomic Transition Probability Bibliographic Database (http://physics.nist.gov/fvalbib) and NIST Atomic Spectral Line Broadening Bibliographic Database (http://physics.nist.gov/linebrbib). References to publications containing critically compiled data can be found in a separate database of NIST compilations of atomic spectroscopy data (http://physics.nist.gov/PhysRefData/datarefs/datarefs_search_form.html).

This page, "Iodine atom", is part of the NIST Chemistry WebBook. This site and its contents are part of the NIST Standard Reference Data Program.

This database contains benchmark results for simulation of plasma population kinetics and emission spectra. The data were contributed by the participants of the 4th Non-LTE Code Comparison Workshop who have unrestricted access to the database. The only limitation for other users is in hidden labeling of the output results. Guest users can proceed to the database entry page without entering userid and password.

This database contains benchmark results for simulation of plasma population kinetics and emission spectra. The data were contributed by the participants of the 3rd Non-LTE Code Comparison Workshop who have unrestricted access to the database. The only limitation for other users is in hidden labeling of the output results. Guest users can proceed to the database entry page without entering userid and password.

This page, "Xenon", is part of the NIST Chemistry WebBook. This site and its contents are part of the NIST Standard Reference Data Program.

This data collection contains 5,228 infrared spectra of different compounds along with chemical structures for most of them. Spectra are provided on a CD-ROM in the JCAMP-DX (Joint Committee for Atomic and Molecular Physical Data 'Data Exchange') format. Chemical structures are provided in the MOL-file format. The IR data originated from two sources, from the so-called 'EPA Vapor-Phase IR Library' and from NIST laboratories. The data have been sub-divided in two ways: 1) as concatenated JCAMP and SDF files (concatenated MOL-files) and 2) in individual files where each spectrum and structure is provided in a separate JCAMP and MOL file, using file names containing the CAS registry number of the compound. Important Note: All spectra were measured in the gas phase by GC/IR (gas chromatography/infrared spectroscopy), hence concentrations in the IR cell are not known or estimable. Molar absorption coefficients are not reported. This data provides only relative absorption coefficients as a function of wavelength which can be used for identification, not quantification.

Table 1. Results of the analysis of excited primary-ion-beam admixtures possibly present in the experiment. The calculations were performed using the Cowan code [27]. The estimated fractions are the coefficients kE obtained from fitting equation (3) to the experimental data. Calculated excitation energies are given in column 4. The experimentally obtained ionization threshold energies (T.E.), T.E. taken from NIST Atomic Spectra Database [28] and T.E. calculated within the configuration-averaged approximation are provided in columns 5, 6 and 7, respectively. The estimated excited-levels' lifetimes and flight times of ions between the source and the interaction region are provided in the last two columns, respectively. The numbers in square brackets are powers of 10 to be multiplied with the preceding numbers, respectively. Abstract Electron-impact single-ionization cross sections of Snq + ions in charge states q = 4–13 with 4d[10 − (q − 4)] outer-shell configurations have been studied in the energy range from the corresponding thresholds up to 1000 eV. Absolute cross sections and fine-step energy-scan data have been measured employing the crossed-beams technique. Contributions of different ionization mechanisms have been analysed by comparing the experimental data with calculations employing the configuration-averaged distorted wave approximation. Ionization plasma rate coefficients inferred from the experimental data are also presented.

The database contains radiative line-binned opacities for lanthanides (atomic number 57<=Z<=70) and actinides (atomic number 89<=Z<=102) which are of paramount importance for simulation of light curves and spectra produced by kilonovae. The opacities were calculated by the LANL group under the assumption of local thermodynamic equilibrium. The temperature grid cover the range from 0.01 eV to 5.0 eV while the mass density grid covers 16 orders of magnitude. The database provide search and selection tools along with graphical and tabular outputs.

This page, "potassium", is part of the NIST Chemistry WebBook. This site and its contents are part of the NIST Standard Reference Data Program.

Table 1. Energy levels (in Ry) of the target states of Ne3 + and comparison with available NIST data [37]. The values with superscript '*' are deduced from the experimental results of the x-ray emission spectrum [38]. Abstract A close-coupling calculation is performed for the photoionization cross section of the high-lying core-excited state 1s2s22p5 1Po of Ne2 + in the energy region of the double K-vacancy resonance 1s02s22p6 1S. The calculation is carried out by using the R-matrix method in the LS-coupling scheme, which includes 27 target states and extensive configuration interaction. The KK-KL x-ray energy, rate and autoionization width of the double K-vacancy state, together with KK-KLL Auger energies and branching ratios of the main channels, are obtained from the cross sections and the contributions of these channels. The calculated resonance energy and x-ray rate are in good agreement with the existing experimental and theoretical results. For the Auger width, our result agrees well with the available experimental result and it is very close to the average of other theoretical data, which shows considerable differences with each other. The Auger energy of the predominate channel KK-KL23L23 2D is in rather good agreement with recent experiments on the Auger spectra. Our branching ratios for the channels KK-KL23L23 2D and KK-KL23L23 2S are larger than the results obtained by the multi-configuration Dirac–Fock method by ~20% on average, which may be due to the coupling of the continuum channels.

This data set consist of two representations of the electron-induced copper k-alpha x-ray emission spectrum. One file contains rebinned counting data, and is close to 'raw'. The second file contains a least-squares spline of the data, which should be a highly useful representation for computational purposes.

The package consists of a set of computer programs for calculation of energy levels, radiative transition wavelengths and probabilities, electron impact excitation and photoionization cross sections, etc. The programs were originally written by Robert D. Cowan in 1962-1991 (see R.D. Cowan, The theory of atomic structure and spectra, University of California Press, Berkeley - Los Angeles - London, 1981). The dataset was updated in November, 2021.

This dataset represents the results of calculations of atomic absorption spectra for the case of two-color EIT. We compare computation methods, specifically Gaussian sampling, to find that one sampling method converges to smooth transmittance curves in less time than the other. We also include some example scripts which generate and plot the figure data.

This page, "helium", is part of the NIST Chemistry WebBook. This site and its contents are part of the NIST Standard Reference Data Program.