NIST Chemistry WebBookContains: thermochemical data for over 7000 organic and small inorganic compounds, reaction thermochemistry data for over 8000 reactions, IR spectra for over 16,000 compounds, mass spectra for over 15,000 compounds UV/Vis spectra for over 1600 compounds, electronic and vibrational spectra for over 4500 compounds, constants of diatomic molecules (spectroscopic data) for over 600 compounds Ion energetics data for over 16,000 compounds, and thermophysical property data for 34 fluids.