title: Dissociation of CH4 at high pressures and temperatures: diamond formation in giant planet interiors?
abstract: Experiments using laser-heated diamond anvil cells show that methane (CH4) breaks down to form diamond at pressures between 10 and 50 gigapascals and temperatures of about 2000 to 3000 kelvin. Infrared absorption and Raman spectroscopy, along with x-ray diffraction, indicate the presence of polymeric hydrocarbons in addition to the diamond, which is in agreement with theoretical predictions. Dissociation of CH4 at high pressures and temperatures can influence the energy budgets of planets containing substantial amounts of CH4, water, and ammonia, such as Uranus and Neptune.
authors.affiliation: Department of Physics, Department of Geology and Geophysics, University of California, Berkeley, CA 94720, USA.
authors.forename: L R
authors.initials: LR
authors.lastname: Benedetti
authors.forename: J H
authors.initials: JH
authors.lastname: Nguyen
authors.forename: W A
authors.initials: WA
authors.lastname: Caldwell
authors.forename: H
authors.initials: H
authors.lastname: Liu
authors.forename: M
authors.initials: M
authors.lastname: Kruger
authors.forename: R
authors.initials: R
authors.lastname: Jeanloz
mesh_terms: D018130:Diamond / Q000737:chemistry*; D019419:Evolution, Planetary; D006358:Hot Temperature; D006838:Hydrocarbons / Q000737:chemistry; D008697:Methane / Q000737:chemistry*; D018541:Neptune; D011312:Pressure; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman; D018540:Uranus; D014961:X-Ray Diffraction
chemical_list: D006838:Hydrocarbons; D018130:Diamond; D008697:Methane