Ueno et al 2024 Source Data

Source Data for Ueno et al. "Synthesis of 13C-depleted organic matter from CO in a reducing early Martian atmosphere"Source Data for FiguresEditable pdf of the Extended Data Figures 1, 2 and 3Extended Data Fig. 1| Calculated fractionation factors for CO2 photolysis in our experimental condition. Upper panels: Measured incident UV spectra of the Xe lamp (black) and photolysis rate coefficients (blue: 12CO2, red: 13CO2) showing larger isotopic fractionation accompanied by photolysis in the wavelength region longer than 183 nm. Grey lines represent actinic UV spectra calculated for shielding by 33 kPa CO2 itself after an absorption path of 13 cm, which are almost identical to those of the UV source. Middle panels: Absorption cross sections for 12CO2 (blue) and 13CO2 (red) calculated from first principles at 295 K (left) and 320 K (right) by Schmidt et al.17 with that of O2 (black) for comparison. Bottom panels: Estimated isotope effect (1000 ln a1) depending on UV shielding up to a 13 cm path length in the experiment for 10 kPa CO2 (red) and 33 kPa CO2 (blue) (see Method). The case when 100 Pa O2 was added to 33 kPa CO2 is also shown in green.Extended Data Fig. 2| Results from the early Mars atmosphere model, assuming 10 mbar PCO2 at the surface. a. Blue and yellow lines represent assumed vertical profiles of PCO2 and temperature, respectively. b. Vertical profile of CO2 photolysis rate (reaction R1). c. Calculated isotope effect (1000 ln a1) of the CO2 photolysis. The red and blue lines show the results assuming surface temperatures of 300 and 240 K, respectively. The shaded area represents the uncertainty of the calculation (see Method). d. Calculated actinic UV spectrum at each altitude. e. J(l) values calculated for each altitude.Extended Data Fig. 3| Results from the early Mars atmosphere model, assuming 100 mbar PCO2 at the surface. a. Blue and yellow lines represent assumed vertical profiles of PCO2 and temperature, respectively. b. Vertical profile of CO2 photolysis rate (reaction R1). c. Calculated isotope effect (1000 ln a1) of the CO2 photolysis. The red and blue lines show the results assuming surface temperatures of 300 and 240 K, respectively. The shaded area represents the uncertainty of the calculation (see Method). d. Calculated actinic UV spectrum at each altitude. e. J(l) values calculated for each altitude.