Giant-planet chemistry: Ammonium hydrosulfide (NH4SH), its IR spectra and thermal and radiolytic stabilities

Mark J. Loeffler, Reggie L. Hudson, Nancy J. Chanover, Amy A. Simon

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Here we present our recent studies of proton-irradiated and unirradiated ammonium hydrosulfide, NH4SH, a compound predicted to be an important tropospheric cloud component of Jupiter and other giant planets. We irradiated both crystalline and amorphous NH4SH at 10-160 K and used IR spectroscopy to observe and identify reaction products in the ice, specifically NH3 and long-chained sulfur-containing ions. Crystalline NH4SH was amorphized during irradiation at all temperatures studied with the rate being the fastest at the lowest temperatures. Irradiation of amorphous NH4SH at ~10-75 K showed that 60-80% of the NH4+ remained when equilibrium was reached, and that NH4SH destruction rates were relatively constant within this temperature range. Irradiations at higher temperatures produced different dose dependence and were accompanied by pressure outbursts that, in some cases, fractured the ice. The thermal stability of irradiated NH4SH was found to be greater than that of unirradiated NH4SH, suggesting that an irradiated giant-planet cloud precipitate can exist at temperatures and altitudes not previously considered.

Original languageEnglish (US)
Pages (from-to)181-191
Number of pages11
JournalIcarus
Volume258
DOIs
StatePublished - Sep 1 2015
Externally publishedYes

Keywords

  • Atmosphere
  • Atmospheres
  • Chemistry
  • Experimental techniques
  • Geophysics
  • Ices
  • IR spectroscopy
  • Jupiter

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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