Refractive indices of pyrolytic graphite, amorphous carbon, and flame soot in the temperature range 25° to 600°C☆

Abstract A technique was developed that allows the determination of the temperature dependence of the refractive indices of carbonaceous materials from ellipsometric intensity measurements on bulk samples. The refractive indices of the carbonaceous samples pyrolytic graphite, amorphous carbon and flame soot were determined over the temperature range 25–600°C and the spectral region 400–700 nm. For all three samples it was found that the inferred refractive index shows insignificant variation with temperature for this range of temperature and wavelength. These results differ by 30 percent or more from the predictions of the Drude Lorentz dispersion model which has been used extensively to predict the variation of the optical properties of carbonaceous particulates. A new set of dispersion constants is presented that accurately predict the indices in the temperature range 25–600°C and in the wavelength range 400–700 nm.

[1]  C. R. Howarth,et al.  Optical constants of carbons and coals in the infrared , 1968 .

[2]  K D Möller,et al.  Infrared optical constants of black powders determined from reflection measurements. , 1981, Applied optics.

[3]  N. C. Barford.  Experimental Measurements: Precision, Error and Truth , 1967 .

[4]  R. Azzam,et al.  Ellipsometry and polarized light : North Holland, Amsterdam, 1987 (ISBN 0-444-87016-4). xvii + 539 pp. Price Dfl. 75.00. , 1987 .

[5]  T. T. Charalampopoulos,et al.  In Situ Optical Properties of Soot Particles in the Wavelength Range from 340 nm to 600 nm , 1988 .

[6]  G. W. Autio,et al.  The normal spectral emissivity of isotropic and anisotropic materials , 1965 .

[7]  Z. Kam,et al.  Absorption and Scattering of Light by Small Particles , 1998 .

[8]  T. Charalampopoulos.  An automated light scattering system and a method for the in situ measurement of the index of refraction of soot particles , 1987 .

[9]  L. Richards,et al.  Tinting strength of carbon black , 1972 .

[10]  R. Azzam,et al.  Ellipsometry and polarized light , 1977 .

[11]  T T Charalampopoulos,et al.  Surface-roughness effects on the determination of optical properties of materials by the reflection method. , 1991, Applied optics.

[12]  S. Chippett,et al.  The size and optical properties of soot particles , 1978 .

[13]  H. Philipp,et al.  Optical Properties of Graphite , 1965 .

[14]  N. C. Hien,et al.  Design and operation of an automated, high-temperature ellipsometer , 1974 .

[15]  D. E. Aspnes,et al.  Polarimetry of Specular and Non-Multiple-Scattered Electromagnetic Radiation from Selectively Roughened Si Surfaces , 1978 .

[16]  J. Janzen.  The refractive index of colloidal carbon , 1979 .

[17]  J. D. Felske,et al.  Determination of the Refractive Indices of Soot Particles from the Reflectivities of Compressed Soot Pellets , 1984 .

[18]  A. F. Sarofim,et al.  Optical Constants of Soot and Their Application to Heat-Flux Calculations , 1969 .

[19]  J. D. Felske,et al.  Refractive indices of soot particles deduced from in-situ laser light scattering measurements , 1987 .

[20]  C. Batten.  Spectral optical constants of soots from polarized angular reflectance measurements. , 1985, Applied optics.

[21]  W. D. Erickson,et al.  Light scattering measurements on soot in a benzeneair flame , 1964 .

[22]  S. C. Graham.  The Refractive Indices of Isolated and of Aggregated Soot Particles , 1974 .

[23]  D. Aspnes.  Optimizing precision of rotating-analyzer ellipsometers , 1974 .

[24]  T. Charalampopoulos,et al.  The effects of temperature and composition on the complex refractive index of flame soot , 1989 .

[25]  T. Charalampopoulos,et al.  Method to minimize the effects of polarizer leakage on reflectivity measurements. , 1990, Applied optics.

[26]  T. Charalampopoulos,et al.  Method for azimuthal alignment in fixed-angle ellipsometry. , 1992, Applied optics.