The effect of experimentally observed hot atom mechanism on the phase diagram using Pt (111) surface of the monomer-dimer reaction has been studied. While using this mechanism, whenever O2 molecule hits the randomly vacant selected site, it breaks up into atomic form and then executes ballistic flight. The path of the two oxygen atoms is taken exactly opposite to each other i.e. anti-parallel and range of the atoms is taken equal i.e. they may fly upto 1 and 1.73 atomic spacing from the site of impact . Two cases have been studied on the basis of the range of hot atoms. The steady reactive window is observed and the continuous transition disappears. As soon as the CO partial pressure departs from zero the production of CO2 is observed, which clearly verifies the experimental observation.