Optical Properties of Graphite and Absorption and Scattering Cross Sections for Graphite Grains Note: this is a static copy (as of 2016 August 3) of data from http://www.astro.princeton.edu/~draine/dust/D16graphite/D16graphite.html If the above URL is accessible, it is recommended, as there may be additional data available there that is not present here. -------------------- The data provided here are from the paper "Graphite Revisited" (Draine 2016, ApJ accepted). Please cite that paper if you use these data. The data are of two types: 1. Complex dielectric functions for graphite (both E||c and E perp c). 2. Absorption and scattering cross sections for grains composed of graphite, including both spheres and spheroids. Dielectric functions ==================== Draine (2016) presents a new estimate for the dielectric tensor of graphite, from submm to X-ray energies. The files below present dielectric functions, and cross sections for spherical and spheroidal grains calculated using these dielectric functions: callindex.out_D16perp_0.100_20K.gz dielectric function for graphite, for E perpendicular to c, where c, the "crystal axis", is normal to the "basal plane". callindex.out_D16para_0.100_20K.gz dielectric function for graphite, for E || c. callindex.out_D16MGemt_0.100_20K.gz estimated "effective" dielectric function for turbostratic graphite, estimated using Maxwell Garnett effective medium theory, with the E perp c component treated as inclusions [referred to as method MG_1 in Draine (2016)]. Cross sections for single-crystal graphite spheres ================================================== Draine (2016) has carried out accurate DDA calculations (using DDSCAT 7.3.1) with full treatment of the anisotropic dielectric tensor, for absorption and scattering by randomly-oriented single-crystal graphite spheres, for wavelengths from 0.1um to 10um. The results in these files are obtained by extrapolation to N=infinity from DDA calculations with N_1=59278 and N_2=140408 dipoles. Results are given for different values of aeff = radius of sphere. ----- filename -------- aeff(um) dda_extrap_ba1.00_0.005 0.005 dda_extrap_ba1.00_0.007 0.007 dda_extrap_ba1.00_0.010 0.010 dda_extrap_ba1.00_0.015 0.015 dda_extrap_ba1.00_0.020 0.020 dda_extrap_ba1.00_0.030 0.030 dda_extrap_ba1.00_0.050 0.050 dda_extrap_ba1.00_0.070 0.070 dda_extrap_ba1.00_0.100 0.100 dda_extrap_ba1.00_0.150 0.150 dda_extrap_ba1.00_0.200 0.200 dda_extrap_ba1.00_0.300 0.300 Cross sections for single-crystal graphite spheroids ==================================================== Draine (2016) has carried out accurate DDA calculations (using DDSCAT 7.3.1) with full treatment of the anisotropic dielectric tensor of graphite, for absorption and scattering by randomly-oriented graphite oblate spheroids (axial ratio b/a=1.4; c axis parallel to the spheroid symmetry axis) for selected sizes, for wavelengths from 0.1um to 10um. The results in these files were obtained by extrapolation to N=infinity from DDSCAT calculations with N_1=60476 and N_2=131040 dipoles. Results are given for selected values of aeff = radius of equal-volume sphere. ----- filename -------- aeff(um) dda_extrap_ba1.40_0.005 0.005 dda_extrap_ba1.40_0.007 0.007 dda_extrap_ba1.40_0.010 0.010 dda_extrap_ba1.40_0.015 0.015 dda_extrap_ba1.40_0.020 0.020 dda_extrap_ba1.40_0.030 0.030 dda_extrap_ba1.40_0.050 0.050 dda_extrap_ba1.40_0.070 0.070 dda_extrap_ba1.40_0.100 0.100 dda_extrap_ba1.40_0.150 0.150 dda_extrap_ba1.40_0.200 0.200 dda_extrap_ba1.40_0.300 0.300 Cross sections for turbostratic graphite spheres ================================================ For spheres composed of turbostratic graphite: callqcomp.out_D16MGemt.gz: Q_ext, Q_abs, Q_sca, , and calculated for isotropic spheres with dielectric function obtained from Maxwell Garnett effective medium theory [method MG_1 in Draine (2016)]. 41 radii (0.001 micron to 10 micron) and 3501 wavelengths (1.0 cm to 10.0 A), uniformly spaced in log(radius) and log(wavelength). planck_D16MGemt.out: Planck-averaged , for absorption and radiation pressure, calculated for turbostatic graphite spheres for 25 selected radii from 0.001 micron to 10 micron, using effective dielectric function MG_1 from Draine (2016), for radiation color temperatures from T=10K to 5x10^5 K. Cross sections for turbostratic graphite spheroids ================================================== Scattering and absorption cross sections for spheroids composed of turbostratic graphite, using Maxwell Garnett effective medium theory (method MG_1 in Draine 2016) to estimate the effective dielectric function for turbostratic graphite material. Efficiency factors Q_abs=C_abs/pi*aeff^2, Q_ext=C_ext/pi*aeff^2, and Q_abs=C_abs/pi*aeff^2, where aeff = radius of equal-volume sphere. Cross sections were calculated using the "spheroid" code of Voshchinnikov & Farafanov (1993) plus approximations when size/wavelength is either very small or very large. Cross sections are calculated for 3 orientations of the spheroid symmetry axis "a" relative to the incident linearly-polarized plane wave: jori=1: k || a , E perp a jori=2: k perp a , E || a jori=3: k perp a , E perp a Q_abs(jori=1-3,jrad,jwav), Q_ext(jori=1,3,jrad,jwav), and Q_sca(jori=1,3,jrad,jwav) are tabulated for 169 sizes [log10(aeff/um)=-3.50 to 0.70] and 1009 wavelengths [log10(lambda/um)= -1.04 to 4.00]. Data are stored in Fortran ordering convention: first index varying most rapidly, i.e., Qabs(1,0,0), Qabs(2,0,0), Qabs(3,0,0), Qabs(1,1,0), Qabs(2,1,0), ... , Qabs(2,168,1008), Qabs(3,168,1008). Files are gzipped. qlib_gra_D16MGemt_1.400.gz : oblate spheroids with axial ratio b/a=1.4 qlib_gra_D16MGemt_2.000.gz : oblate spheroids with axial ratio b/a=2.0