The behavior of spectral features in the infrared emission from particulate surfaces of various grain sizes

Abstract

Several inorganic materials are used to illustrate that bands in infrared emission spectra of solids change shape as the particle size of the sample is altered, and that the way in which a particular band changes depends upon the value of its absorption coefficient. The relationship found to exist between corresponding band shape changes in emission and reflection spectra indicates that Kirchoff's law holds to a first‐order approximation for particulate, or mat, surfaces. The implications of band shape changes are discussed in relation to remote compositional sensing, and it is pointed out as a consequence that the most obvious spectral features used for the identification of samples with polished surfaces are not necessarily the most useful for determining the composition of a target with a rough or mat surface.

The Infrared Interferometer Experiment on Nimbus 3

“…Some minerals exhibit the phenomenon of reststrahlen in this spectral interval (Aronson, et al 1967;Hovis,1966;Hovis, et al 1968;Hunt and Vincent, 1968;Lyon, 1965). Laboratory measurements show a correlation of the location of the reststrahlen peaks in the spectral reflectance curves of various silicate bear ing minerals with their SiO 2 content.…”

Texture and Porosity Effects on the Thermal Radiative Behavior of Alumina Ceramics

“…Besides, in addition to these progressive modifications, the band shapes were markedly modified in comparison with those of the single crystal but the bands shapes did not evolve significantly with the increase in porosity between 500 and 900 cm -1 . Several authors [10,[15][16][17][18][19] showed that the band shape of the spectral emissivity was dependent on the grain size and the grain shape constituting the surface of the sample. Several types of behaviors appeared according to the particle size and the value of the absorption coefficient K (e.g.…”

The Effect of the Particle Size on the Fundamental Vibrations of the [CO32–] Anion in Calcite

“…Type 3 4 behavior involves an increase in spectral contrast with decreasing particle size. 10 The calcite ν3 anti-symmetric stretching mode shows type 1 behavior, whereas the [CO3 are dependent on the wavelength. The critical diameter for a transition in optical properties is related to the absorption coefficient (α) and is proportional to wavelength (λ) and (k) defined as 2,13 :…”