NIST Physical Reference Data

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

Examples of how to reference these online databases are provided in the "Version History" pages.


Physical Constants	Fundamental Physical Constants
	Searchable Bibliography on the Constants
		International System of Units (SI) or see Special Publication 811
		Guidelines for Evaluating and Expressing Measurement Uncertainty

Periodic Table of the Elements	Periodic Table: Atomic Properties of the Elements
		Contains NIST critically-evaluated data on atomic properties of the elements. Suitable for high-resolution color printing for desk or wall-chart display.

Atomic Spectroscopy Data	Atomic Spectra Database
Status of Atomic Spectroscopy Data	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
	NLTE Databases and Codes
		FLYCHK Collisional-Radiative Code SAHA Plasma Population Kinetics Database NLTE4 Plasma Population Kinetics Database
	Spectrum of Platinum Lamp for Ultraviolet Spectrograph Calibration
	X-ray Transition Energies
	Bibliographic Databases on Atomic Spectroscopy
		Atomic Transition Probabilities Atomic Spectral Line Broadening Atomic Energy Levels and Wavelengths

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

The use of International Units and the expression of uncertainty in measurement is critical to all data activities. For information on these topics, see guidelines for evaluating and expressing measurement uncertainty, and information on the International System of Units (SI).

Additional data and databases are being prepared for this server.

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Online: June 1994 - Last update: September 2007