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The Cosmic Ice Laboratory - IR Spectra

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 open-source 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, open-source, easy-to-use, and available in both a Python and a Windows-executable 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, open-source 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, open-source 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.


Methyl Acetate

    The Excel file at this address 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 (accepted, in press).

Allene

    The Excel file at this address 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

    The Excel file at this address 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

    The Excel file at this address 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 (NH3)

    The Excel file at this address has the real (n) and imaginary (k) parts of the complex index of refraction of amorphous and crystalline ammonia, NH3. A full description is in Gerakines, Yarnall, & Hudson, 2022, The Astrophysical Journal.

Hydrogen Cyanide (HCN)

    The Excel file at this address 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 (N2O)

    The Excel file at this address has the real (n) and imaginary (k) parts of the complex index of refraction of amorphous and crystalline nitrous oxide, N2O. A full description is in Gerakines & Hudson, 2020, The Astrophysical Journal.

Carbon Dioxide (CO2)

    The Excel file at this address has the real (n) and imaginary (k) parts of the complex index of refraction of amorphous and crystalline carbon dioxide, CO2. A full description is in Gerakines & Hudson, 2020, The Astrophysical Journal.

Methane (CH4)

    The Excel file at this address has the real (n) and imaginary (k) parts of the complex index of refraction of amorphous and crystalline methane, CH4. A full description is in Gerakines & Hudson, 2020, The Astrophysical Journal.

Methanol (CH3OH)

    The Excel file at this address has the real (n) and imaginary (k) parts of the complex index of refraction of amorphous and crystalline methanol, CH3OH. A full description is in Gerakines & Hudson, 2020, The Astrophysical Journal.

C3 Hydrocarbon Ices (propane, propylene, propyne)

    The Excel file at this address 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)CH2CH3) Ice

    The Excel file at this address 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(CH3)2) Ice

    The Excel file at this address 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 ((HCC-C(=O)H) Ice

    The Excel file at this address 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 and infrared spectra were recorded at 10 K. For more details, see Hudson & Gerakines, Monthly Notices of the Royal Astronomical Society, 2019, 482, 4009.

Acetone ((CH3)2CO) 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 (CH4) 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 (C2H6) 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 here (pdf format).

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 (C2H4) 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 here (pdf format).

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 (C2H2) 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 near-IR regions, near 3500 cm-1.

    A copy of the paper describing this work is available here (pdf format).

Region Ice Phase Temperatures (K) Data
Near-IR Amorphous 12, 20, 30, 40, 50, 60, 70 Spectrum       n       k
  Crystalline 15, 20, 30, 40, 50, 60, 70 Spectrum       n       k
Mid-IR 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 far-IR regions, near 500 cm-1.

    Each table is in the machine-readable format used by The Astrophysical Journal.

    A copy of the paper describing this work is available here (pdf format).

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
C2N2 Amorphous 50, 75 n       k
  Crystalline 20, 35, 50, 75, 95 n       k
CH3CN Amorphous 50, 75, 95, 110 n       k
Crystalline 20, 35, 50, 75, 95, 110, 130 n       k
C2H5CN Amorphous 50, 75, 95, 110 n       k
Crystalline 20, 35, 50, 75, 95, 110, 140 n       k
HC3N Amorphous 50, 75, 95 n       k
Crystalline 20, 35, 50, 75, 95, 110 n       k


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  • Last Updated: 07-Aug-2022