X-ray emission from scattering and fluorescence of solar x-rays at Venus and Mars

X-ray emission is modeled and x-ray intensities are predicted for Venus and Mars. Two emission mechanisms are studied: (1) elastic scattering of solar x-rays by atmospheric neutrals, (2) absorption of solar x-rays in either t he carbon or oxygen K-shells followed by fluorescent emission of x-rays. Th e carbon and oxygen atoms reside in the carbon dioxide molecules. We predic t total soft x-ray intensities of approximately 0.67 R for Venus and 0.15 R for Mars, corresponding to total soft x-ray luminosities of about 35 MW an d 2.5 MW, respectively. These luminosities exceed the x-ray luminosities ex pected from the solar wind charge exchange mechanism.