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Solid‐state photochemistry as a formation mechanism for Titan's stratospheric C 4 N 2 ice clouds
Author(s) -
Anderson C. M.,
Samuelson R. E.,
Yung Y. L.,
McLain J. L.
Publication year - 2016
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2016gl067795
Subject(s) - stratosphere , polar , ice cloud , ozone depletion , titan (rocket family) , sublimation (psychology) , atmospheric sciences , astrobiology , ozone , water vapor , water ice , photochemistry , atmospheric chemistry , chemistry , meteorology , geology , physics , astronomy , radiative transfer , optics , psychology , psychotherapist
We propose that C 4 N 2 ice clouds observed in Titan's springtime polar stratosphere arise due to solid‐state photochemistry occurring within extant ice cloud particles of HCN‐HC 3 N mixtures. This formation process resembles the halogen‐induced ice particle surface chemistry that leads to condensed nitric acid trihydrate (NAT) particles and ozone depletion in Earth's polar stratosphere. As our analysis of the Cassini Composite Infrared Spectrometer 478 cm −1 ice emission feature demonstrates, this solid‐state photochemistry mechanism eliminates the need for the relatively high C 4 N 2 saturation vapor pressures required (even though they are not observed) when the ice is produced through the usual procedure of direct condensation from the vapor.