Infrared Emission Spectroscopy

Dependence of diffusive radiative transfer on grain-size, temperature, and Fe-content: Implications for mantle processes

“…(4) and (5). Kirchoff's law has been experimentally confirmed (Low and Coleman, 1966;Bates, 1978). The above references, Evans (1992), and Hofmeister et al (2003) provide additional discussion of emissivity and grain-size.…”

Thermodynamic and optical thickness corrections to diffusive radiative transfer formulations with application to planetary interiors

“…Kirchhoff's law for a body in thermodynamic equilibrium requires that emissivity equals absorptivity, defined as a ( ν , Τ ) = I abs / I 0 , where I abs is the intensity of light actually absorbed and I 0 is the intensity entering the crystal [e.g., Bates , ; Brewster , ]. The approximation ε = 1 − r from behavior of opaque material should not be applied to partially transparent insulators due to the existence of a thermal gradient [see McMahon , ; Gardon , ; Bates , ; discussed further by Hofmeister and Criss , ; Hofmeister , ]. Instead, emissivity is approximated from Kirchhoff's law for dielectrics: where d is average grain size.…”

Origin of HED Meteorites from the Spalling of Mercury - Implications for the Formation and Composition of the Inner Planets

“…If the surface is covered with dust, this layer is heated by lattice conduction from below and emitted light comes only from this layer. Because reflection peaks are broader than absorption peaks, emissions from a dusty surface go as I BB = I BB and peaks point up as seen in spectra from small grains (Low & Coleman, 1966;Bates, 1978) and references therein.…”

“…Kirchhoff's law for a body in thermodynamic equilibrium requires that absorptivity (= I abs /I 0 , where I abs = the intensity of light actually absorbed) equals emissivity () (e.g., Bates, 1978;Brewster 1992). For an opaque material such as a metal, 1= +r, where r =I ref /I 0 is reflectivity.…”

“…Although asteroids are large and opaque, dust grains on their surface are partially transparent. For the part of the asteroid that is sampled, 1= +r +t, where t = I tran /I 0 is transmittivity of the uppermost layer as derived by Bates (1978) for dielectrics (e.g. silicates).…”