DIMER PHOTOCHEMISTRY IN THE PALEOATMOSPHERE

1. E. C. Zipf University of Pittsburgh (Edczipf@aol.com) & Sheo S. Prasad Creative Research Enterprises (ssp@creativeResearch.org) DIMER PHOTOCHEMISTRY IN THE PALEOATMOSPHERE • Dimer Photochemistry may have been very important in the prebiological paleoatmosphere before the advent of the biological photosynthesis • May have influenced the evolution of the primitive marine life and also of the O3 layer during the time period when the O2 layer was developing Creative Research Enterprises’ Presentation EGS2000/ST9-02 Paper # ST029

2. DIMER PHOTOCHEMISTRY WAS IMPORTANT DUE TO LOW ATMOSPHERIC TEMPERATURES Illustration for the era of O2 level = 10-4 present Creative Research Enterprises’ Presentation EGS2000/ST9-02 Paper # ST029

3. IN O2-DEFICIENT PALEOATMOSPHERE DIMER PHOTOCHEMISTRY MAY HAVE DONE THINGS NOT POSSIBLE IN THE PRESENT ATMOSPHERE With O2 being at 10-5 to 10-3 PAL (Present Atmospheric Level), the chemically significant UV penetrated the region where dimer population is appreciable. Flux at the ground for various O2 levels Creative Research Enterprises’ Presentation EGS2000/ST9-02 Paper # ST029

4. NOX PRODUCTION: AN EXAMPLE OF IMPORTANT ROLE OF DIMER PHOTOCHEMISTRY IN PALEOATMOSPHERE O2•N2 + hv (200-250 nm) NO +NO • Laboratory experiments put wavelength averaged quantum yield () at  3.3 x 10-2 NO /photon • Also dimerization might facilitate the spin forbidden absorption of these photons by O2 of the O2•N2 dimer • N & NO2 as the primary products are ignored since N+ NO2 N2O + O Creative Research Enterprises’ Presentation EGS2000/ST9-02 Paper # ST029

5. TOTAL NOX PRODUCTION RATE WAS SUBSTANTIAL • Assuming -averaged  was valid for each wavelength bin • Note, the total NOX production rate was considerable at even the ground level Creative Research Enterprises’ Presentation EGS2000/ST9-02 Paper # ST029

6. LET US PUT THE DIMER NOX PRODUCTION IN A PROPER PERSPECTIVE • The N2O + O(1D)  NO +NO was insignificant due to deep penetration of the UV • Lightning is thought to be the only important source of NOX in the post-bolide impact era • The dimer source, however, may have been 50 to 100 times larger than the lightning source • The dimer was thus the most important NOX source in the post-bolide prebiological paleoatmosphere Creative Research Enterprises’ Presentation EGS2000/ST9-02 Paper # ST029

7. THIS DIMER CHEMISTRY MAY HAVE AFFECTED THE EVOLUTION OF LIFE IN OCEAN AND LAND • Since it was a global tropospheric source, it was particularly effective in providing nutrients to marine life in the post-bolide impact era • It may have created a low-altitude paleoionosphere that modified the electrical properties of the Precambrian atmosphere. • It may have influenced the pace of formation of the O3 shield over the biosphere when the O2 was growing from its prebiological level to the present level Creative Research Enterprises’ Presentation EGS2000/ST9-02 Paper # ST029

8. CONCLUDING REMARKS • The dimer photochemistry may have been quite important in the prebiological paleoatmosphere • It is therefore hoped that this presentation will motivate the key measurements- the wavelength dependence of the quantum yield Creative Research Enterprises’ Presentation EGS2000/ST9-02 Paper # ST029