Spectral Emissivity & Emittance

The “Emissivity” page on the FAR Associates website includes a discussion of their unique instrument along with graphs and some tables of spectral emissivity values are evidently all reproduced from the Thermophysical Properties of Matter, Vol. 7: Thermal Radiative Properties, Y.S. Touloukian and D.P. DeWitt, IFI/Plenum, New York, 1970. These include curves for: Carbon (Graphite), Tungsten, Aluminum, Copper, Iridum, Iron, Molybdenum, Silicaon Carbide, Stainless Steel and Titanium.

The ASTER spectral library, is a compilation of almost 2000 spectra of natural and man made materials that is searchable by material. The search returns a list of materials that match your search criteria, you can see a scaled plot of the spectrum and the ancillary information information for the spectrum, you can also download the spectral data.

Data and (No. of samples) are: Minerals (1348), Rocks (244), Soils (58), Vegetation (4), Water, Snow & Ice (9), Man made materials (56), Lunar (17) and Meteorites (60)

This link provides a downloadable pdf copy of Vol 9 of the introductory section of Thermal Properties of Matter compendium published by IFI/Plenum in 1970. The sestion deals with the theoretical background and methods of measurement of the optical properties presented. These include spectral emissivity.

The Raytek North America website includes a table for the emissivity of a large range of non-metallic materials that includes common building materials, ceramics, glasses and natural materials including ice & water in as many as four wavelength regions.

Wavebands covered include 1.0 micrometer (micron), 5.0 microns, 7.9 microns and the 8-14 micron band. No specific data and the limits of the various wavebands and there are many instances where the wavelength region is labelled as “nr” meaning “Not Recommended”.

Infrared Theory Notes-(Last updated 04/11/04, PDF Download of 547kb - 43 pages) contains not only some simple explanations of the key features of Radiation Thermometry, how it works and how IR Thermometers work in various measurement situations, but also provides some unique graphical representations of the transmission of glasses (see pages 30-33).

It also discusses thin plastics. In the latter case, see pages 34-36 for unique emissivity data and curves versus material type and thickness at 3.43 micrometers (microns) and explanations of an alternate choice waveband region at 7.9 microns.