Swift heavy ion processing of CH₃CN ices: Structure and implications for Titan’s lower atmosphere nitrile chemistry
Abstract
Swift heavy ion irradiation of pure CH 3 CN ice was investigated to evaluate the influence of the initial ice morphology on its radiolytic evolution under astrophysically relevant conditions. Two deposition protocols were compared: (i) CH 3 CN ice deposited and irradiated at 50 K, and (ii) CH 3 CN ice deposited at 130 K, subsequently cooled to 10 K prior to irradiation, thereby preserving the structural organization established during deposition. In situ FTIR spectroscopy revealed efficient destruction of CH 3 CN and the formation of HCN, HC 3 N, CH 3 NC, NH 3 , and imine-like compounds. The thermally organized ice exhibited a distinct infrared spectral evolution, enhanced destruction, and differences in the stabilization of daughter species compared with the amorphous ice. Destruction cross sections of (2.85 ± 0.52) × 10 -12 and (4.65 ± 0.43) × 10 -12 cm 2 were determined for the amorphous and thermally organized ices, respectively. These results demonstrate that the thermal history of CH 3 CN ice, through its influence on the initial ice morphology, strongly affects radical diffusion, recombination, and product formation during irradiation. The present measurements provide benchmark radiochemical data for acetonitrile and establish a basis for future investigations of more realistic nitrile-bearing astrophysical ice analogues relevant to Titan and other outer Solar System environments.
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BibTeX
@article{murhej2026swift,
title = {{Swift heavy ion processing of CH₃CN ices: Structure and implications for Titan’s lower atmosphere nitrile chemistry}},
author = {Y. Murhej and A.L.F. de Barros and R. Sreeja and D.V. Doreste and E.F. da Silveira and A.A. de Almeida and H. Rothard and Alicja Domaracka},
journal = {Icarus},
year = {2026},
month = sep,
doi = {10.1016/j.icarus.2026.117287},
url = {https://hal.science/hal-05742352v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Swift heavy ion processing of CH₃CN ices: Structure and implications for Titan’s lower atmosphere nitrile chemistry
AU - Y. Murhej
AU - A.L.F. de Barros
AU - R. Sreeja
AU - D.V. Doreste
AU - E.F. da Silveira
AU - A.A. de Almeida
AU - H. Rothard
AU - Alicja Domaracka
PY - 2026
DA - 2026/09/08
JO - Icarus
DO - 10.1016/j.icarus.2026.117287
UR - https://hal.science/hal-05742352v1
AB - Swift heavy ion irradiation of pure CH 3 CN ice was investigated to evaluate the influence of the initial ice morphology on its radiolytic evolution under astrophysically relevant conditions. Two deposition protocols were compared: (i) CH 3 CN ice deposited and irradiated at 50 K, and (ii) CH 3 CN ice deposited at 130 K, subsequently cooled to 10 K prior to irradiation, thereby preserving the structural organization established during deposition. In situ FTIR spectroscopy revealed efficient destruction of CH 3 CN and the formation of HCN, HC 3 N, CH 3 NC, NH 3 , and imine-like compounds. The thermally organized ice exhibited a distinct infrared spectral evolution, enhanced destruction, and differences in the stabilization of daughter species compared with the amorphous ice. Destruction cross sections of (2.85 ± 0.52) × 10 -12 and (4.65 ± 0.43) × 10 -12 cm 2 were determined for the amorphous and thermally organized ices, respectively. These results demonstrate that the thermal history of CH 3 CN ice, through its influence on the initial ice morphology, strongly affects radical diffusion, recombination, and product formation during irradiation. The present measurements provide benchmark radiochemical data for acetonitrile and establish a basis for future investigations of more realistic nitrile-bearing astrophysical ice analogues relevant to Titan and other outer Solar System environments.
SN - 0019-1035
SN - 1090-2643
ER -