Sulfuric acid optical constants data
from our published manuscript:
"Infrared optical constants of low-temperature H2SO4 solutions representative of stratospheric sulfate aerosols"
Robert T. Tisdale, David L. Glandorf, Margaret
A. Tolbert and Owen B. Toon
J. Geophys. Res., 103, 25,353-25,370, 1998
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Introduction
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This page contains files relating to optical constants of sulfuric acid
solutions. There are eight files with the raw measured optical constants, a file with the
fit parameters for equations 7 and 8 in the text of the manuscript and a Fortran program
which can be used with the fit parameter file to calculate the optical constants for any
composition of H2SO4. The use of the fit parameters with the Fortran
program is the recommended method of using these data. Each file will be described in
further detail in later sections.
The spectral data used to determine the optical constants were
collected using FTIR spectroscopy of low temperature sulfuric acid films. An error
minimization routine using an analytical transmission model and a Kramers-Kronig
transformation was used to determine the optical constants. For more detail, see the
manuscript.
The filenames for the raw data are in the format "wt???.txt",
where ??? refers to the weight percent. For example, "wt500.txt" contains the
raw optical constants for 50.0 wt% sulfuric acid.
The file "fitparam.txt" contains the fit parameters, and the
file "saocfit.txt" is the Fortran program which uses "fitparam.txt" to
generate optical constants using equations 7 and 8 from the manuscript. This is the method
we recommend for generating optical constants of any composition, including those for
which raw optical constants are available. For more details on this, see the manuscript.
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Download Instructions
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Any of the files accessible by the links below can be downloaded to your local computer. For Netscape 4.0 on a PC, this can be done in two ways. You can left-click on the link, and then select "Save As" on the "File" menu. Or, you can right-click on the link itself and hold the button down until a menu appears, and select the "Save Link As" choice. On a Mac, only the first method will work. Other internet browsers should have similar options for saving the files.
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fitparam.txt
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This file contains the fit parameters which are used to generate the optical constants of any composition between 45 and 85 wt% H2SO4. Equations 7 and 8 in the manuscript are used to generate the optical constants using these parameters. A Fortran program has been written to do this automatically - see the section on saocfit.txt.
Column 1: frequency, in wavenumber (or cm-1)
Column 2: fit parameter p3 for use in equation 7 in the manuscript to generate
n values.
Column 3: fit parameter p2 for use in equation 7 in the manuscript to generate
n values.
Column 4: fit parameter p1 for use in equation 7 in the manuscript to generate
n values.
Column 5: fit parameter p0 for use in equation 7 in the manuscript to generate
n values.
Column 6: fit parameter q3 for use in equation 8 in the manuscript to generate
k values.
Column 7: fit parameter q2 for use in equation 8 in the manuscript to generate
k values.
Column 8: fit parameter q1 for use in equation 8 in the manuscript to generate
k values.
Column 9: fit parameter q0 for use in equation 8 in the manuscript to generate
k values.
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saocfit.txt
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The file "saocfit.txt" uses the file "fitparam.txt"
to generate optical constants for any composition between 45 and 80 wt% H2SO4.
The file "saocfit.txt" is a Fortran program, and should be renamed to
"saocfit.f" or saocfit.for" before use, as required by your Fortran
compiler. The program was developed and tested using Fortran PowerStation 4.0 on a
Windows98 system, and modifications may be necessary for use on other Fortran systems.
You will first be prompted for the composition for which you wish to
generate optical constants. Then, you must choose between two methods of frequency input.
You can choose to specify the starting and ending frequency and the frequency interval
within the program. You can also choose to specify a file which contains your desired
frequencies. An example file containing our frequencies, freq.txt, is
included in the supplement for demonstration purposes, and in case you wish to use our
frequencies. The order of frequencies in the file is unimportant.
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wt452.xt
wt500.txt
wt551.txt
wt616.txt
wt653.txt
wt702.txt
wt750.txt
wt800.txt
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Raw data for H2SO4 solutions at 215 K. Each filename refers to the weight percent H2SO4 , for example, wt452.txt is the raw data for 45.2 wt% H2SO4 . We recommend using the fitting program saocfit.txt instead of the raw data, however.
Column 1: frequency, in wavenumber (or cm-1)
Column 2: n, the real refractive index (unitless) at the frequency listed in column 1.
Column 3: k, the imaginary refractive index (unitless) at the frequency listed in column
1.
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