Mass-independent Fractionation of Oxygen Isotopes During Spin-forbidden Photolysis of CO2 in the Martian Atmosphere

Details Mass-independent Fractionation of Oxygen Isotopes During Spin-forbidden Photolysis of CO2 in the Martian Atmosphere Mass-independent Fractionation of Oxygen Isotopes During Spin-forbidden Photolysis of CO2 in the Martian Atmosphere

Oct 2010

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010dps....42.3026l&link_type=abstract

American Astronomical Society, DPS meeting #42, #30.26

Astronomy and Astrophysics

Astronomy

Scientific paper

Some secondary mineral phases in SNC meteorites exhibit mass-independent oxygen isotope signatures (i.e., an excess of 17O relative to equilibrium isotope abundances). Because these isotope anomalies have been interpreted as evidence for either 1) loss of a large fraction of the atmosphere1 or 2) gas-phase mass-independent chemistry2, it is necessary to elucidate the relevant mass-independent processes. The two largest sources of oxygen isotope mass-independent fraction (MIF) in the Martian atmosphere are the spin-forbidden photolysis of CO2 from 167 to 202 nm, and the gas-phase formation of O3. The MIF associated with O3 formation has been well studied in the laboratory and in Earth's atmosphere, and is believed to be a result of non-statistical chemistry during energy redistribution in the vibrationally excited O3* (3). The isotope effects due to spin-forbidden CO2 photolysis are less well characterized. Experiments4 at 185 nm have demonstrated a yield of nearly pure 17O with Δ17O 50 ‰ in CO and O2, most likely due to a hyperfine interaction in C16O17O. Assuming that similar MIF signatures apply at wavelengths > 185 nm, the MIF signatures of CO and O will be 50 ‰ at altitudes below 60 km. (The principal CO2 formation reaction, , also produces a small MIF of 2 ‰ at low pressure5, but is minor compared to CO2 photolysis and O3 formation.) In this poster we will describe model simulations and planned experiments designed to better quantify oxygen isotope MIF due to spin-forbidden CO2 photolysis.
1Jakosky 1993.
2Farquhar and Thiemens 2000.
3Gao and Marcus 2001.
4Bhattacharya et al. 2000.
5Rockmann et al. 1998.

Affiliated with

Also associated with

No associations

Rating

Mass-independent Fractionation of Oxygen Isotopes During Spin-forbidden Photolysis of CO2 in the Martian Atmosphere does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Mass-independent Fractionation of Oxygen Isotopes During Spin-forbidden Photolysis of CO2 in the Martian Atmosphere, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Mass-independent Fractionation of Oxygen Isotopes During Spin-forbidden Photolysis of CO2 in the Martian Atmosphere will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1122894