Source of nitrogen isotope anomaly in HCN in the atmosphere of Titan

Mao Chang Liang; Alan N. Heays; Brenton R. Lewis; Stephen T. Gibson; Yuk L. Yung

doi:10.1086/520881

Source of nitrogen isotope anomaly in HCN in the atmosphere of Titan

Mao Chang Liang^*, Alan N. Heays, Brenton R. Lewis, Stephen T. Gibson, Yuk L. Yung

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

91 Citations (Scopus)

Abstract

The ¹⁴N/¹⁵N ratio for N₂ in the atmosphere of Titan was recently measured to be a factor of 2 higher than the corresponding ratio for HCN. Using a one-dimensional photochemical model with transport, we incorporate new isotopic photoabsorption and photodissociation cross sections of N₂, computed quantum-mechanically, and show that the difference in the ratio of ¹⁴N/¹⁵N between N ₂ and HCN can be explained primarily by the photolytic fractionation of ¹⁴N¹⁴N and ¹⁴N ¹⁵N. The [HC ¹⁴N]/[HC ¹⁵N] ratio produced by N₂ photolysis alone is 23. This value, together with the observed ratio, constrains the flux of atomic nitrogen input from the top of the atmosphere to be in the range (1-2) × 10⁹ atoms cm^-2 s^-1.

Original language	English
Pages (from-to)	L115-L118
Journal	Astrophysical Journal
Volume	664
Issue number	2 II
DOIs	https://doi.org/10.1086/520881
Publication status	Published - 1 Aug 2007

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@article{52501c8c378241a19ddfc8087fedfddf,

title = "Source of nitrogen isotope anomaly in HCN in the atmosphere of Titan",

abstract = "The 14N/15N ratio for N2 in the atmosphere of Titan was recently measured to be a factor of 2 higher than the corresponding ratio for HCN. Using a one-dimensional photochemical model with transport, we incorporate new isotopic photoabsorption and photodissociation cross sections of N2, computed quantum-mechanically, and show that the difference in the ratio of 14N/15N between N 2 and HCN can be explained primarily by the photolytic fractionation of 14N14N and 14N 15N. The [HC 14N]/[HC 15N] ratio produced by N2 photolysis alone is 23. This value, together with the observed ratio, constrains the flux of atomic nitrogen input from the top of the atmosphere to be in the range (1-2) × 109 atoms cm-2 s-1.",

keywords = "Atmospheric effects, Methods: numerical, Molecular processes, Planetary systems planets and satellites: individual (Titan), Radiative transfer",

author = "Liang, {Mao Chang} and Heays, {Alan N.} and Lewis, {Brenton R.} and Gibson, {Stephen T.} and Yung, {Yuk L.}",

year = "2007",

month = aug,

day = "1",

doi = "10.1086/520881",

language = "English",

volume = "664",

pages = "L115--L118",

journal = "Astrophysical Journal",

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publisher = "American Astronomical Society",

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}

TY - JOUR

T1 - Source of nitrogen isotope anomaly in HCN in the atmosphere of Titan

AU - Liang, Mao Chang

AU - Heays, Alan N.

AU - Lewis, Brenton R.

AU - Gibson, Stephen T.

AU - Yung, Yuk L.

PY - 2007/8/1

Y1 - 2007/8/1

N2 - The 14N/15N ratio for N2 in the atmosphere of Titan was recently measured to be a factor of 2 higher than the corresponding ratio for HCN. Using a one-dimensional photochemical model with transport, we incorporate new isotopic photoabsorption and photodissociation cross sections of N2, computed quantum-mechanically, and show that the difference in the ratio of 14N/15N between N 2 and HCN can be explained primarily by the photolytic fractionation of 14N14N and 14N 15N. The [HC 14N]/[HC 15N] ratio produced by N2 photolysis alone is 23. This value, together with the observed ratio, constrains the flux of atomic nitrogen input from the top of the atmosphere to be in the range (1-2) × 109 atoms cm-2 s-1.

AB - The 14N/15N ratio for N2 in the atmosphere of Titan was recently measured to be a factor of 2 higher than the corresponding ratio for HCN. Using a one-dimensional photochemical model with transport, we incorporate new isotopic photoabsorption and photodissociation cross sections of N2, computed quantum-mechanically, and show that the difference in the ratio of 14N/15N between N 2 and HCN can be explained primarily by the photolytic fractionation of 14N14N and 14N 15N. The [HC 14N]/[HC 15N] ratio produced by N2 photolysis alone is 23. This value, together with the observed ratio, constrains the flux of atomic nitrogen input from the top of the atmosphere to be in the range (1-2) × 109 atoms cm-2 s-1.

KW - Atmospheric effects

KW - Methods: numerical

KW - Molecular processes

KW - Planetary systems planets and satellites: individual (Titan)

KW - Radiative transfer

UR - http://www.scopus.com/inward/record.url?scp=34547991744&partnerID=8YFLogxK

U2 - 10.1086/520881

DO - 10.1086/520881

M3 - Article

SN - 0004-637X

VL - 664

SP - L115-L118

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 2 II

ER -

Source of nitrogen isotope anomaly in HCN in the atmosphere of Titan

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