Simultaneous spectroscopic detection of adsorbed and gas-phase species durign atomospherically relevant heterogeneous reactions.

摘要

The application of a recently developed ATR-IR flow cell coupled with an FTIR gas phase detection system to simultaneously monitor the gas-phase and surface composition durign the well-known reaction of nitrogen oxide gases NO_2 and N_2O_5 withNaCl powder is preported.Infrared absorption band assignments for the major products are presented for species in the gas and solid phase,and correlations between the appearance of gas phase and surface species are used to follow the reactions qualtitatively in real time.The reaction of NO_2 with NaCl produces the expected surface NO~-_3 and gaseous C1NO products,but is also observed ot produce in a minor reaction channel a second surface nitrate species correlatied withsurface water loss asaresult of heterogeneous hydrolysis.The reaction of N_2O_5 similarly prodcues C1NO_2 in teh gas phase and a surface nitrate in one reaction channel,with simultaneous production of a significant amount of gas-phase HNO_3 in a second heterogeneous hydrolysis reaction channel.These observations confirm the usefullness of the combined surface and gas phase analytical methodologty in following the mechanistic and kinetic detail of atmospherically relevant reactions.