The Cosmic Ice Laboratory  Optical Constants from IR Spectra
Optical Constants  Free Software
Astrochemists and others have been calculating optical constants (n and k) for decades, but there seems to be no free and opensource software for such work. The program we wrote (almost entirely the work of Perry Gerakines) is described in a paper in The Astrophysical Journal (Gerakines & Hudson, 2020). A copy of the software is here, as a "zipped" file. It's free, fast, accurate, opensource, easytouse, and available in both a Python and a Windowsexecutable version.
If you find this program helpful in your research then please acknowledge any use by reference to "Gerakines & Hudson, 2020" and this NASA web site. Variations of this work come to mind, and so we would be glad to have copies of any improvements you make.
Interference Fringes  Free Software
This Excel file (394 kilobytes) will allow you to fit a set of interference fringes with a method similar to that described by Romanescu et al. (Icarus, 2010). The calculation is not particularly difficult, but we are unaware of a free, opensource computer routine for doing it, and that employs a straightforward graphical user interface. We have tested the file given here and know that it works with Excel and the OpenOffice package. Note that there are instructions in the second and third tabs at the bottom of the spreadsheet.
If you find this file helpful in your research then please acknowledge any use by reference to "Hudson et al." and this NASA web site. Variations of this work come to mind, and so we would be glad to have copies of any improvements you make.
Spectral Calculation  Free Software
This Excel file (4.76 megabytes) will allow you to calculate IR transmission spectra from optical constants, n and k, based on the method of Swanepoel (1983) referenced in the file. The calculation is not particularly difficult, but we are unaware of a free, opensource computer routine for doing it, and using a straightforward graphical user interface. We have tested the file given here and know that it works with Excel and the OpenOffice package.
If you find this file helpful in your research then please acknowledge any use by reference to "Hudson et al." and this NASA web site. Many variations of this file come to mind, and so we would be glad to have copies of any improvements you make.
Carbon Monoxide
This Excel file (1.37 megabytes) has the real (n) and imaginary (k) parts of the complex index of refraction of alphacrystalline CO (carbon monoxide) at 25 K at resolutions of 0.5 and 1 cm^{1}. A full description is in Gerakines, Materese, and Hudson, Monthly Notices of the Royal Astronomical Society, 2023 (accepted, in press).
Cyclopropane and Ethylene Oxide
This Excel file (3.77 megabytes) has the real (n) and imaginary (k) parts of the complex index of refraction of amorphous and crystalline cyclopropane and ethylene oxide (oxirane). A full description is in Hudson, Yarnall, and Gerakines, 2023, Icarus.
Methyl Acetate
This Excel file (2.81 megabytes) has the real (n) and imaginary (k) parts of the complex index of refraction of amorphous and crystalline methyl acetate. A full description is in Yarnall and Hudson, 2022, Spectrochimica Acta.
Allene
This Excel file (4.45 megabytes) has the real (n) and imaginary (k) parts of the complex index of refraction of amorphous and crystalline allene. A full description is in Hudson and Yarnall, 2022, ACS Earth and Space Chemistry.
Methylamine and Ethylamine
This Excel file (5.57 megabytes) has the real (n) and imaginary (k) parts of the complex index of refraction of amorphous and crystalline methyl and ethylamine. A full description is in Hudson, Yarnall, and Gerakine, 2022, Astrobiology.
Benzene and Pyridine
This Excel file (4.92 megabytes) has the real (n) and imaginary (k) parts of the complex index of refraction of amorphous and crystalline benzene and pyridine. A full description is in Hudson & Yarnall, 2022, Icarus.
Ammonia (NH_{3})
This Excel file (3.07 megabytes) has the real (n) and imaginary (k) parts of the complex index of refraction of amorphous and crystalline ammonia, NH_{3}. A full description is in Gerakines, Yarnall, & Hudson, 2022, The Astrophysical Journal.
Hydrogen Cyanide (HCN)
This Excel file (2.64 megabytes) has the real (n) and imaginary (k) parts of the complex index of refraction of amorphous and crystalline hydrogen cyanide, HCN. A full description is in Gerakines, Yarnall, & Hudson, 2022, Monthly Notices of the Royal Astronomical Journal.
Nitrous Oxide (N_{2}O)
This Excel file (10.48 megabytes) has the real (n) and imaginary (k) parts of the complex index of refraction of amorphous and crystalline nitrous oxide, N_{2}O. A full description is in Gerakines & Hudson, 2020, The Astrophysical Journal.
Carbon Dioxide (CO_{2})
This Excel file (5.78 megabytes) has the real (n) and imaginary (k) parts of the complex index of refraction of amorphous and crystalline carbon dioxide, CO_{2}. A full description is in Gerakines & Hudson, 2020, The Astrophysical Journal.
Methane (CH_{4})
This Excel file (5.69 megabytes) has the real (n) and imaginary (k) parts of the complex index of refraction of amorphous and crystalline methane, CH_{4}. A full description is in Gerakines & Hudson, 2020, The Astrophysical Journal.
Methanol (CH_{3}OH)
This Excel file (6.61 megabytes) has the real (n) and imaginary (k) parts of the complex index of refraction of amorphous and crystalline methanol, CH_{3}OH. A full description is in Gerakines & Hudson, 2020, The Astrophysical Journal.
C3 Hydrocarbon Ices (propane, propylene, propyne)
This Excel file (19.42 megabytes) has the real (n) and imaginary (k) parts of the complex index of refraction of amorphous and crystalline propane, propylene, and propyne. A full description is in a manuscript of Hudson et al. 2021, accepted for publication in Icarus.
Propanal (Propionaldehyde, HC(O)CH_{2}CH_{3}) Ice
This Excel file (1.40 megabytes) has the real (n) and imaginary (k) parts of the complex index of refraction of amorphous and crystalline propanal (propionaldehyde). For details concerning temperature, spectral resolution, sample preparation, and so on, see Yarnall et al., Monthly Notices of the Royal Astronomical Society, 2020.
Dimethyl Ether (O(CH_{3})_{2}) Ice
This Excel file (1.20 megabytes) has the real (n) and imaginary (k) parts of the complex index of refraction of amorphous and crystalline dimethyl ether. For details concerning temperature, spectral resolution, sample preparation, and so on, see Hudson et al., Spectrochimica Acta, 2020.
Propynal (HCCC(=O)H) Ice
This Excel file (2.31 megabytes) has tables of the real (n) and imaginary (k) parts of the complex index of refraction of amorphous propynal at 10 K. The sample was made andinfrared spectra were recorded at 10 K. For more details, see Hudson & Gerakines, Monthly Notices of the Royal Astronomical Society, 2019, 482, 4009.
Acetone ((CH_{3})_{2}CO) Ice
Links to tables of the real (n) and imaginary (k) parts of the complex index of refraction of solid acetone are given below. Note that these two files are in the Excel (xlsx) format.
Region 
Initial Ice Phase 
Temperature and Data 
3600  500 cm^{1} 
Amorphous 
10 K

3600  500 cm^{1} 
Crystalline 
125 K

Methane (CH_{4}) Ice
A link to a table of the real (n) and imaginary (k) parts of the complex index of refraction, and the transmission spectrum, of methane ice is given below. Note that the amorphous phase will crystallize on warming. — More methane data are posted above.
Region 
Initial Ice Phase 
Temperature and Data 
5000  400 cm^{1} 
Amorphous 
10 K  spectra, n, and k

Ethane (C_{2}H_{6}) Ices
Links to tables of the real (n) and imaginary (k) parts of the complex index of refraction, and transmission spectra, of ethane ices are given below. Note that the amorphous and metastable ices crystallize on warming.
A copy of the paper describing this work is available as a PDF.
Region 
Initial Ice Phase 
Temperatures (K) and Data 
4500  500 cm^{1} 
Amorphous 
16,
20,
30,
40,
50,
60


Metastable 
11,
20,
30,
40,
50
60


Crystalline 
12,
20,
30,
40,
50,
60

Ethylene (C_{2}H_{4}) Ices
Links to tables of the real (n) and imaginary (k) parts of the complex index of refraction, and transmission spectra, of ethylene ices are given below. Note that the amorphous and metastable ices crystallize on warming.
A copy of the paper describing this work is available as a PDF.
Region 
Initial Ice Phase 
Temperatures (K) and Data 
5000  700 cm^{1} 
Amorphous 
12,
20,
30,
40,
50,
60


Metastable 
14,
20,
30,
40,
50,
60


Crystalline 
16,
20,
30,
40,
50,
60

Acetylene (C_{2}H_{2}) Ices
Links to tables of the real (n) and imaginary (k) parts of the complex index of refraction, and transmission spectra, of acetylene ices are given below. Note that there is overlap in the tables between the mid and nearIR regions, near 3500 cm^{1}.
A copy of the paper describing this work is available as a PDF.
Region 
Ice Phase 
Temperatures (K) 
Data 
NearIR 
Amorphous 
12, 20, 30, 40, 50, 60, 70 
Spectrum

n

k


Crystalline 
15, 20, 30, 40, 50, 60, 70 
Spectrum

n

k

MidIR 
Amorphous 
12, 20, 30, 40, 50, 60, 70 
Spectrum

n

k


Crystalline 
15, 20, 30, 40, 50, 60, 70 
Spectrum

n

k

Nitrile Ices
Links to tables of the real (n) and imaginary (k) parts of the complex index of refraction of nitrile ices are given below. Note that there is overlap in the tables between the mid and farIR regions, near 500 cm^{1}.
Each table is in the machinereadable format used by The Astrophysical Journal.
A copy of the paper describing this work is available as a PDF
Nitrile Ice 
Ice Phase 
Temperatures (K) 
Data 
HCN 
Amorphous 
50, 75, 95, 110 
n

k


Crystalline 
20, 35, 50, 75, 95, 110, 120 
n

k

C_{2}N_{2} 
Amorphous 
50, 75 
n

k


Crystalline 
20, 35, 50, 75, 95 
n

k

CH_{3}CN 
Amorphous 
50, 75, 95, 110 
n

k


Crystalline 
20, 35, 50, 75, 95, 110, 130 
n

k

C_{2}H_{5}CN 
Amorphous 
50, 75, 95, 110 
n

k


Crystalline 
20, 35, 50, 75, 95, 110, 140 
n

k

HC_{3}N 
Amorphous 
50, 75, 95 
n

k


Crystalline 
20, 35, 50, 75, 95, 110 
n

k
