This data base contains the rotational spectral lines observed and reported in the open literature for 55 triatomic molecules through June 1976. The isotopic molecular species, assigned quantum numbers, observed frequency, estimated measurement uncertainty and reference are given for each transition reported. In addition to correcting a number of misprints and errors in the literature cited, the spectral lines for approximately 15 molecules have been refit to produce a comprehensive and consistent analysis of all the data extracted from various literature sources. Both measured and predicted transition frequencies are listed for several isotopic forms of HCN, H2O, H2S, and OCS. The derived molecular properties, such as rotational and centrifugal distortion constants, hyperfine structure constants, electric dipole moments, and rotational g-factors are listed with one standard deviation uncertainty for all values.

This data base contains the rotational spectral lines observed and reported in the open literature for 55 triatomic molecules through June 1976. The isotopic molecular species, assigned quantum numbers, observed frequency, estimated measurement uncertainty and reference are given for each transition reported. In addition to correcting a number of misprints and errors in the literature cited, the spectral lines for approximately 15 molecules have been refit to produce a comprehensive and consistent analysis of all the data extracted from various literature sources. Both measured and predicted transition frequencies are listed for several isotopic forms of HCN, H2O, H2S, and OCS. The derived molecular properties, such as rotational and centrifugal distortion constants, hyperfine structure constants, electric dipole moments, and rotational g-factors are listed with one standard deviation uncertainty for all values.

This database contains critically evaluated transition frequencies for the molecular transitions detected in interstellar and circumstellar clouds reported in the literature through mid-2008. The tabulated transition frequencies are recommended for reference in future astronomical observations in the centimeter and millimeter wavelength regions. The transition frequencies have been selected through a critical examination and analysis of the laboratory spectral data obtained from the literature. The information tabulated includes the species identity, transition frequency, uncertainty, and quantum state labels. For convenience, representative line antenna temperatures are listed for a typical astronomical source for each transition, and the references are cited for the laboratory and astronomical literature that have been employed. 2009 Revision

Wavenumber Calibration Tables from Heterodyne Frequency Measurements contains tables of gas-phase infrared transition wavenumbers and their spectroscopic assignments that are appropriate for calibrating high-spectral-resolution infrared spectrometers. The calibration lines for carbonyl sulfide (OCS), nitrous oxide (N2O), nitric oxide (NO), carbonyl sulfide (CS2), and carbon monoxide (CO) collectively extend from approximately 486 wavenumber (cm-1) to 4355 wavenumbers (cm-1) in the infrared. The bibliography and spectral atlas are current through November 1994. The bibliography covers a range of high-resolution spectroscopic studies on the calibration molecules listed above, including pressure broadening studies.

The NIST Computational Chemistry Comparison and Benchmark Database is a collection of experimental and ab initio thermochemical properties for a selected set of gas-phase molecules. The goals are to provide a benchmark set of experimental data for the evaluation of ab initio computational methods and allow the comparison between different ab initio computational methods for the prediction of gas-phase thermochemical properties. The data files linked to this record are a subset of the experimental data present in the CCCBDB.

The NIST Computational Chemistry Comparison and Benchmark Database is a collection of experimental and ab initio thermochemical properties for a selected set of gas-phase molecules. The goals are to provide a benchmark set of experimental data for the evaluation of ab initio computational methods and allow the comparison between different ab initio computational methods for the prediction of gas-phase thermochemical properties. The data files linked to this record are a subset of the experimental data present in the CCCBDB.

**** Note that this SRD is superseded by SRD 64 Version 4.0. ****The NIST Electron Elastic-Scattering Cross-Section Database provides values of differential elastic-scattering cross sections, total elastic-scattering cross sections, phase shifts, and transport cross sections in electron-atom scattering for elements with atomic numbers from 1 to 96 and for electron energies between 50 eV and 300 keV (in steps of 1 eV). Knowledge of elastic-scattering effects is important for the development of theoretical models for quantitative analysis by Auger-electron spectroscopy, X-ray photoelectron spectroscopy, electron microprobe analysis, and analytical electron microscopy. These data are also needed for modeling of electron transport in radiation dosimetry, electron-beam lithography, and interactions of ionizing radiation with matter. The database is designed to facilitate simulations of electron transport for these and similar applications in which electron energies from 50 eV to 300 keV are utilized.An analysis of available elastic-scattering cross-section data has been published [A. Jablonski, F. Salvat, and C. J. Powell, J. Phys. Chem. Ref. Data 33, 409 (2004)].

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.

These data files contain the data for the measured transition frequencies shown in Table I and the traces in Figure 3 of the publication "Frequency-comb spectroscopy on pure quantum states of a single molecular ion," accessible at https://arxiv.org/abs/1911.12808. In this publication we use generally applicable quantum-logic techniques to prepare a trapped molecular ion in a single quantum state, drive terahertz rotational transitions with an optical frequency comb, and read out the molecular state non-destructively, leaving the molecule ready for further manipulation. One file contains data For Table 1. In the measurement of rotational transition frequencies, the intensities of the comb beams are varied to characterize the effect of AC Stark shift, while the intensity ratio between the sigma and pi polarized beams are kept at close to 2. The average intensity of the sigma-polarized comb beam is quantified by measuring the resultant Stark shift, fSS_sigma, on the 729 nm transition of the Ca+ ion, with the Ca+ ion where the CaH+ ion would be during rotational spectroscopy experiments. The other file contains data for Figure 3, (a) Spectra for the J = 4 to 2 transition: 40CaH+ is prepared in J = 2, followed by a pulse train from the comb Raman beams probing the J = 2 to J = 4 transition. After the probe pulse train, projective measurements of both initial and final states are performed and the state occupation probability is determined. The probe time is ~1.6 ms. The frequency shows the offset of the Raman difference frequency from the resonant value. (b) Rabi flopping on the J = 4 to J = 2 transition: Starting in J = 4, with the comb Raman pulse detuning set to resonance, the state of the 40CaH+ ion is driven coherently to J = 2 by a pulse train of variable duration from the comb Raman beams. The center wavelength of the frequency comb was ~800 nm for these spectra and Rabi flopping traces. The error bars stand for ±1 standard deviation.

Note that this SRD supersedes SRD 64 Version 3.2. The NIST Electron Elastic-Scattering Cross-Section Database provides values of differential elastic-scattering cross sections, total elastic-scattering cross sections, phase shifts, and transport cross sections in electron-atom scattering for elements with atomic numbers from 1 to 96 and for electron energies between 50 eV and 300 keV (in steps of 1 eV). Knowledge of elastic-scattering effects is important for the development of theoretical models for quantitative analysis by Auger-electron spectroscopy, X-ray photoelectron spectroscopy, electron microprobe analysis, and analytical electron microscopy. These data are also needed for modeling of electron transport in radiation dosimetry, electron-beam lithography, and interactions of ionizing radiation with matter. The database is designed to facilitate simulations of electron transport for these and similar applications in which electron energies from 50 eV to 300 keV are utilized. An analysis of available elastic-scattering cross-section data has been published [A. Jablonski, F. Salvat, and C. J. Powell, J. Phys. Chem. Ref. Data 33, 409 (2004)].