Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Infrared properties of SiC particles   We present basic laboratory infrared data on a large number of SiC
particulate samples, which should be of great value for the interpretation of
the 11.3 micron feature observed in the spectra of carbon-rich stars. The
laboratory spectra show a wide variety of the SiC phonon features in the 10-13
micron wavelength range, both in peak wavelength and band shape. The main
parameters determining the band profile are morphological factors as grain size
and shape and, in many cases, impurities in the material. We discovered the
interesting fact that free charge carriers, generated e.g. by nitrogen doping,
are a very common characteristics of many SiC particle samples. These free
charge carriers produce very strong plasmon absorption in the near and middle
infrared, which may also heavily influence the 10-13 micron feature profile via
plasmon-phonon coupling.
  We also found that there is no systematic dependence of the band profile on
the crystal type (alpha- vs. beta-SiC). This is proven both experimentally and
by theoretical calculations based on a study of the SiC phonon frequencies.
Further, we give optical constants of amorphous SiC. We discuss the
implications of the new laboratory results for the interpretation of the
spectra of carbon stars.

5
The categories of this paper are: gr-qc
29
The categories of this paper are: funct-an
4
The categories of this paper are: cond-mat
13
The categories of this paper are: quant-ph
11
The categories of this paper are: hep-lat
37
The categories of this paper are: supr-con
24
The categories of this paper are: dg-ga
3
The categories of this paper are: physics
33
The categories of this paper are: plasm-ph
26
The categories of this paper are: bayes-an
9
The categories of this paper are: nlin
36
The categories of this paper are: cmp-lg
28
The categories of this paper are: alg-geom
20
The categories of this paper are: acc-phys
2
The categories of this paper are: math
25
The categories of this paper are: patt-sol