A book, Vibrational and Electronic Energy Levels of Polyatomic Transient Molecules, by Marilyn E. Jacox [J. Phys. Chem. Ref. Data, Monograph 3 (1994)] and two supplements [M.E. Jacox, J. Phys. Chem. Ref. Data 27(2), 115 (1998); M.E. Jacox, J. Phys. Chem. Ref. Data 32(1), 1 (2003)], provide a unique resource for chemists and engineers. They contain a critical evaluation and summary of the experimentally determined vibrational fundamentals and electronic band origins of approximately 3350 neutral and ionic small transient molecules. The emphasis is on species with lifetimes too short for study using conventional sampling techniques. Such species are frequently present as reaction intermediates, and their detection is essential for in situ monitoring of chemical-based processes.
A number of molecules which might be considered borderline with regard to the short lifetime criterion have been included for the benefit of scientists and engineers concerned with environmental research and monitoring, energetic materials, chemical vapor deposition, and plasma processing.
Spectroscopic measurements in the gas phase, in molecular beams, and in rare-gas and nitrogen matrices have been considered. The types of measurement surveyed include spectrometer and laser-based absorption and emission techniques, laser absorption with mass analysis, and photoelectron spectroscopy. Radiative lifetimes and principal rotational constants are included.
NIST Standard Reference Database No. 69:
A computer-searchable database is available as a part of the NIST Chemistry WebBook. It is designed to give rapid access to experimental data on the ground-state vibrational fundamentals, the electronic energy levels, and excited-state vibrational fundamentals of transient molecules with from 3 to 16 atoms. The associated literature references can also be displayed. There are approximately 3750 molecules represented in the current version, which became available in June 2005.