National Institute of Standards and Technology WebBook

Thermochemical data for over 6000 organic and small inorganic compounds. Reaction thermochemistry data for over 9000 reactions. IR spectra for over 8700 compounds. Mass spectra for over 12,000 compounds. UV/Vis spectra for over 400 compounds. Electronic and vibrational spectra for over 4000 compounds. Constants of diatomic molecules (spectroscopic data) for over 600 compounds. Ion energetics data for over 16,000 compounds. Thermophysical property data for 33 fluids.