Arrhenius parameters for the reactions of H atoms with PH3 and AsH3

Arthur, N. L.; Cooper, Ian

doi:10.1039/a606454j

Cited by 30 publications

(28 citation statements)

References 3 publications

(3 reference statements)

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“…The rate constant for this reaction is 1.1 ´10 -10 cm 3 s -1 at 288K (Kaye and Strobel 1984). The rate constant for H attack on PH3 is 3.3´10 -12 cm 3 s -1 at 288K (Arthur and Cooper 1997 (Kaye and Strobel 1984); if the atmospheres of terrestrial H2-dominated exoplanets behave similarly, this mechanism will not be able to significantly replenish PH3.…”

Section: Reaction Network and Haze Formationmentioning

confidence: 99%

“…In anoxic atmospheres, however, the main source of OH and H radicals is the photolysis of water vapor (Hu et al 2012). Phosphine can be destroyed by the H radical via the reaction: PH3 + H à H2 + PH2 For this reaction, A = 7.22 x 10 -11 cm 3 s -1 , E = 7.37 kJ mol -1 , corresponding to kPH 3 ,H=3 x 10 -12 cm 3 s -1 at T = 288 K (Arthur and Cooper 1997). The reaction of PH3 with the H radical is most relevant to H2-rich atmospheres (Seager et al 2013b).…”

Section: Destruction By O Radicalsmentioning

confidence: 99%

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Phosphine as a Biosignature Gas in Exoplanet Atmospheres

et al. 2020

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A long-term goal of exoplanet studies is the identification and detection of biosignature gases. Beyond the most discussed biosignature gas O2, only a handful of gases have been considered in detail. Here we evaluate phosphine (PH3). On Earth, PH3 is associated with anaerobic ecosystems, and as such it is a potential biosignature gas in anoxic exoplanets.We simulate the atmospheres of habitable terrestrial planets with CO2-and H2-dominated atmospheres, and find that phosphine can accumulate to detectable concentrations on planets with surface production fluxes of 10 10 -10 14 cm -2 s -1 (corresponding to surface concentrations of 10s of ppb to 100s of ppm), depending on atmospheric composition, and UV irradiation. While high, the surface flux values are comparable to the global terrestrial production rate of methane, or CH4 (10 11 cm -2 s -1 ) and below the maximum local terrestrial PH3 production rate (10 14 cm -2 s -1 ). As with other gases, PH3 can more readily accumulate on low-UV planets, e.g. planets orbiting quiet M-dwarfs or with a photochemically generated UV shield.If detected, phosphine is a promising biosignature gas, as it has no known abiotic false positives on terrestrial planets from any source that could generate the high fluxes required for detection. PH3 also has three strong spectral features such that in any atmosphere scenario one of the three will be unique compared to other dominant spectroscopic molecules. PH3's weakness as a biosignature gas is its high reactivity, requiring high outgassing rates for detectability. We calculate that tens of hours of JWST time are required for a potential detection of PH3. Yet, because PH3 is spectrally active in the same wavelength regions as other atmospherically important molecules (such as H2O and CH4), searches for PH3 can be carried out at no additional observational cost to searches for other molecular species relevant to characterizing exoplanet habitability.

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Section: Reaction Network and Haze Formationmentioning

confidence: 99%

Section: Destruction By O Radicalsmentioning

confidence: 99%

Phosphine as a Biosignature Gas in Exoplanet Atmospheres

et al. 2020

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“…Uncertainties in the (R2) reaction, stemming from the ∼15% uncertainty of the rate constant (Arthur and Cooper 1997), propagate into a mere 10% uncertainty of the best-fit eddy diffusion coefficient (see below). On the other hand, uncertainties in the (R1) reaction influence both the direct photolysis of PH 3 and the production of H atoms.…”

Section: Reactionmentioning

confidence: 99%

Vertical Distribution of PH3 in Saturn from Observations of Its 1-0 and 3-2 Rotational Lines

Orton

Serabyn

Lee

2000

Icarus

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“…The behavior of HCP is similar to that of PH 2 ; maximum HCP abundances are ∼ 50 ppb (for solar metallicity) over the P-T range considered here. · · · HD209458b 1260 ∼ 800 a · · · · · · L dwarf 1270 · · · · · · · · · M dwarf · · · · · · · · · · · · Arthur & Cooper (1997) Note. -Convective mixing timescales (in seconds) are t conv ∼ 10 6.3 (1000 K), 10 6.6 (1500 K), and 10 6.9 (2000 K) for Jupiter, 10 7.1 (1000 K), 10 7.5 (1500 K), and 10 7.7 (2000 K) for Gliese 229B, and 10 7.1 to 10 11.1 (1000 K), 10 7.5 to 10 11.5 (1500 K), and 10 7.7 to 10 11.7 (2000 K) for HD209458b.…”

Section: A Additional Compoundsmentioning

confidence: 99%

Atmospheric Chemistry in Giant Planets, Brown Dwarfs, and Low‐Mass Dwarf Stars. II. Sulfur and Phosphorus

Visscher

Lodders

Fegley

2006

ApJ

259

283

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Thermochemical equilibrium and kinetic calculations are used to model sulfur and phosphorus chemistry in giant planets, brown dwarfs, and extrasolar giant planets (EGPs). The chemical behavior of individual S-and P-bearing gases and condensates is determined as a function of pressure, temperature, and metallicity. The results are independent of particular model atmospheres and, in principle, the equilibrium composition along the pressure-temperature profile of any object can be determined. Hydrogen sulfide (H 2 S) is the dominant S-bearing gas throughout substellar atmospheres and approximately represents the atmospheric sulfur inventory. Silicon sulfide (SiS) is a potential tracer of weather in substellar atmospheres. Disequilibrium abundances of phosphine (PH 3 ) approximately representative of the total atmospheric phosphorus inventory are expected to be mixed upward into the observable atmospheres of giant planets and T dwarfs. In hotter objects, several P-bearing gases (e.g., P 2 , PH 3 , PH 2 , PH, HCP) become increasingly important at high temperatures.Subject headings: astrochemistry -planets and satellites: individual (Jupiter) -stars: low-mass, brown dwarfs -stars: individual (Gliese 229B, HD 209458)

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Arrhenius parameters for the reactions of H atoms with PH3 and AsH3

Cited by 30 publications

References 3 publications

Phosphine as a Biosignature Gas in Exoplanet Atmospheres

Phosphine as a Biosignature Gas in Exoplanet Atmospheres

Vertical Distribution of PH3 in Saturn from Observations of Its 1-0 and 3-2 Rotational Lines

Atmospheric Chemistry in Giant Planets, Brown Dwarfs, and Low‐Mass Dwarf Stars. II. Sulfur and Phosphorus

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