J/A+A/483/661 Refractive index for silicon carbide (SiC) (Pitman+, 2008)
Optical properties of silicon carbide for astrophysical applications.
I. New laboratory infrared reflectance spectra and optical constants.
Pitman K.M., Hofmeister A. M., Corman A.B., Speck A.K.
<Astron. Astrophys. 483, 661 (2008)>
=2008A&A...483..661P 2008A&A...483..661P
ADC_Keywords: Spectra, infrared ; Models
Keywords: methods: laboratory - stars: carbon - stars: circumstellar matter -
ISM: dust, extinction
Abstract:
The SiC optical constants are fundamental inputs for radiative
transfer (RT) models of astrophysical dust environments. However,
previously published values contain errors and do not adequately
represent the bulk physical properties of the cubic (β) SiC
polytype usually found around carbon stars. We provide new,
uncompromised optical constants for β- and α-SiC derived
from single-crystal reflectance spectra and investigate quantitatively
(i) whether there is any difference between α- and β-SiC
that can be seen in infrared (IR) spectra and optical functions and
(ii) whether weak features from λ∼12.5-13.0µm need to be
fitted.
We measured mid- and far-IR reflectance spectra for two samples of 3C
(β-)SiC and four samples of 6H (α-)SiC. For the latter
group, we acquired polarized data (E⊥c, E¶c
orientations). We calculated the real and imaginary parts of the
complex refractive index (n(λ)+ik(λ)) and the
ideal absorption coefficients via classical dispersion fits to our
reflectance spectra.
Description:
These data tables contain optical functions for alpha- and
beta-polytypes of silicon carbide (SiC) for wavelengths
∼2.5-200-microns at T=18-19degC and near-normal incidence. The
wavelength mesh in these tables has been regridded for use in DUSTY
(Nenkova et al., 2000ASPC..196..77N). Users are welcome to contact the
authors directly for copies of the high resolution (4000 wavelength
point) files.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
betasic.dat 35 105 Optical constants for 3C-SiC chemical vapor
deposited (CVD) wafer (table 3)
grysicpa.dat 37 105 Optical constants for gray 6H-SiC powder,
extraordinary ray (table 4)
grysicpe.dat 37 105 Optical constants for gray 6H-SiC powder,
ordinary ray (table 5)
moisicpa.dat 37 105 Optical constants for moissanite gem,
extraordinary ray (table 6 )
moisicpe.dat 37 105 Optical constants for moissanite gem,
ordinary ray (table 7)
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Byte-by-byte Description of file: *.dat
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Bytes Format Units Label Explanations
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1- 11 E11.6 um lambda Wavelength
13- 23 E11.7 --- n Real part of complex refractive index
25- 37 E13.6 --- k Imaginary part of complex refractive index
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Acknowledgements: Karly Pitman, Karly.M.Pitman(at)jpl.nasa.gov
Jet Propulsion Laboratory, California Inst. of Technology
(End) Karly M. Pitman [JPL, CIT], Patricia Vannier [CDS] 06-Mar-2008