Elemental Data Index
	Access database holdings organized by element. Use the databases below to access all information.

Physical Constants		Fundamental Physical Constants
		Searchable Bibliography on the Constants
			International System of Units (SI)
			Guidelines for Evaluating and Expressing Measurement Uncertainty
Atomic Spectroscopy Data		Atomic Spectra Database [Version 3.0-beta ] [Version 2.0] [Version 1.3]
		Handbook of Basic Atomic Spectroscopic Data
		Energy Levels of Hydrogen and Deuterium
		Ground Levels and Ionization Energies for the Neutral Atoms
		Spectral Data for the Chandra X-ray Observatory
		Spectrum of Platinum Lamp for Ultraviolet Spectrograph Calibration
		X-ray Transition Energies
		Bibliographic Database on Atomic Transition Probabilities
		Atomic Spectral Line Broadening Bibliographic Database
			Status of Atomic Spectroscopy Data
Molecular Spectroscopic Data		Microwave Spectral Data: Diatomics, Triatomics, and Hydrocarbons
		Wavenumber Tables for Calibration of Infrared Spectrometers
		Frequencies for Interstellar Molecular Microwave Transitions
		Photoionization of CO2 (ARPES)
		Diatomic Calculations: Equations & Underpinning Theory
Atomic and Molecular Data		Electron-Impact Cross Sections for Ionization and Excitation
		Potential Energy Surface Database of Group II Dimer Molecules
X-Ray and Gamma-Ray Data			Note on the X-Ray Attenuation Databases
		X-Ray Attenuation and Absorption for Materials of Dosimetric Interest
		XCOM: Photon Cross Sections Database
		Bibliography of Photon Attenuation Measurements
		X-Ray Form Factor, Attenuation and Scattering Tables
		X-ray Transition Energies
Radiation Dosimetry Data		Stopping-Power and Range Tables for Electrons, Protons, and Helium Ions
Nuclear Physics Data		Radionuclide Half-life Measurements Made at NIST
		Atomic Weights and Isotopic Compositions
Condensed Matter Physics Data		Atomic Model Data for Electronic Structure Calculations
Other NIST Data		Data Gateway
		Online Reference Databases
			Standard Reference Data Catalog