Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Molecular Spectroscopic Data

Microwave Spectral Data: Diatomics, Triatomics, and Hydrocarbons

F.J. Lovas, E. Tiemann, and R.D. Suenram
These three databases of diatomic, triatomic, and hydrocarbon molecules were originally published as spectral tables in the Journal of Physical and Chemical Reference Data. Each of the databases covers primarily the microwave region with some data available for the radio frequency region.

Wavenumber Tables for Calibration of Infrared Spectrometers

Arthur G. Maki and Joseph S. Wells
This database is an atlas of molecular spectra and associated tables of wavenumbers from heterodyne frequency measurements for the calibration of infrared spectrometers. Five molecules are included in the atlas: CO, OCS, N2O, NO, and CS2. The spectra cover the 488 cm-1 to 3120 cm-1 and 4000 cm-1 to 4400 cm-1 regions.

Frequencies for Interstellar Molecular Microwave Transitions

Frank J. Lovas
This database contains critically evaluated transition frequencies for molecular transitions detected in interstellar and circumstellar clouds recommended by NIST 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 through December 2002. 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.

Photoionization of CO2 (ARPES)

A.C. Parr, J.B. West, M.R.F. King, K. Ueda, P.M. Dehmer, and J.L. Dehmer
The vibrational branching ratios and asymmetry parameters for CO2 have been determined in the wavelength region of 650 Å to near the ionization onset at about 840 Å. The study was performed using synchrotron radiation from the Daresbury storage ring that was dispersed with a 5 m grating monochromator that afforded resolution of 0.1 Å to 0.2 Å. This resolution allowed the study of the branching ratios and asymmetry parameters with enough detail to see the changes in the parameters within the pronounced autoionization structure in CO2 in this wavelength region. While the electron spectrometer resolution was not sufficient to resolve the spin orbit and Renner-Teller splitting in the photoelectron spectra, we are able to fit the data with a model that identifies the major structure in terms of the symmetric stretch and elements of the asymmetric stretch and bending modes. A calculation of the expected relative vibrational excitations based upon the Franck-Condon principle clearly showed non-Franck-Condon behavior in some of the vibrational-electronic transitions.

Equations & Underpinning Theory:

Diatomic Rotational Calculations

Jon T. Hougen
Procedures are described, in this pedagogical monograph, for making quantum mechanical calculations of rotational energy levels and rotational line intensities in diatomic molecules. The procedures are illustrated by sample calculations. A familiarity with the material of this report should enable a practicing electronic spectroscopist to carry out, though in a rather mechanical way, his own theoretical calculations for molecules under experimental investigation. The material of this report is aimed at electronic spectroscopists who have had the equivalent of one semester of graduate level quantum mechanics.

Methane Symmetry Operations

Jon T. Hougen
Catalog of explicit symmetry operations for the vibrational, rotational and nuclear spin functions of methane, and the use of these operations in determining symmetry labels and selection rules.


Created June 9, 2009, Updated November 26, 2019