INFRARED SPECTRA AND OPTICAL CONSTANTS OF NITRILE ICES RELEVANT TO TITAN's ATMOSPHERE

Journal Article · Mon Nov 15 00:00:00 EST 2010 · Astrophysical Journal, Supplement Series

DOI:https://doi.org/10.1088/0067-0049/191/1/96· OSTI ID:21457029

Moore, Marla H; Hudson, Reggie ^[1]; Ferrante, Robert F ^[2]

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1. NASA Goddard Space Flight Center, Code 691, Greenbelt, MD 20771 (United States)
2. Chemistry Department, US Naval Academy, 572 Holloway Road, Annapolis, MD 21402 (United States)

Spectra and optical constants of nitrile ices known or suspected to be in Titan's atmosphere are presented from 2.0 to 333.3 {mu}m ({approx}5000-30 cm{sup -1}). These results are relevant to the ongoing modeling of Cassini CIRS observations of Titan's winter pole. Ices studied are: HCN, hydrogen cyanide; C{sub 2}N{sub 2}, cyanogen; CH{sub 3}CN, acetonitrile; C{sub 2}H{sub 5}CN, propionitrile; and HC{sub 3}N, cyanoacetylene. For each of these molecules, we also report new cryogenic measurements of the real refractive index, n, determined in both the amorphous and crystalline phases at 670 nm. These new values have been incorporated into our optical constant calculations. Spectra were measured and optical constants were calculated for each nitrile at a variety of temperatures, including, but not limited to, 20, 35, 50, 75, 95, and 110 K, in both the amorphous phase and the crystalline phase. This laboratory effort used a dedicated FTIR spectrometer to record transmission spectra of thin-film ice samples. Laser interference was used to measure film thickness during condensation onto a transparent cold window attached to the tail section of a closed-cycle helium cryostat. Optical constants, real (n) and imaginary (k) refractive indices, were determined using Kramers-Kronig analysis. Our calculation reproduces the complete spectrum, including all interference effects.

• OSTI ID: 21457029
• Journal Information: Astrophysical Journal, Supplement Series, Vol. 191, Issue 1; Other Information: DOI: 10.1088/0067-0049/191/1/96; ISSN 0067-0049
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ACETONITRILE
AMORPHOUS STATE
ASTROPHYSICS
CONTROLLED ATMOSPHERES
CYANOGEN
FOURIER TRANSFORMATION
HYDROCYANIC ACID
INFRARED SPECTRA
INTERFERENCE
KRAMERS-KRONIG CORRELATION
PLANETS
PROPIOLONITRILE
REFRACTIVE INDEX
SPECTROMETERS
THIN FILMS
ATMOSPHERES
CORRELATIONS
FILMS
HYDROGEN COMPOUNDS
INORGANIC ACIDS
INORGANIC COMPOUNDS
INTEGRAL TRANSFORMATIONS
MEASURING INSTRUMENTS
NITRILES
OPTICAL PROPERTIES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHYSICAL PROPERTIES
PHYSICS
SPECTRA
TRANSFORMATIONS