Séminaire "Physique moléculaire" : Joey Messinger (Caltech, Pasadena CA USA)

Joey Messinger, du groupe de Mitchio Okumura (AA Noyes Laboratory for Chemical Physics, Caltech, Pasadena CA USA), donnera un séminaire sur la chimie atmosphérique expérimentale avec des techniques de spectroscopie laser de pointe.

In Earth’s troposphere, the reaction of OH and NO2 is a critical reaction in the formation of smog, and as a reservoir for HOx and NOx. While initially assumed that the only product is nitric acid (HONO2), it has since been demonstrated that a second channel exists, leading to the production of peroxynitrous acid (HOONO) in small amounts. The yields of HOONO and HONO2 are important parameters for atmospheric models, but vary as a function of temperature and pressure. Our group has previously used mid-infrared cavity ringdown spectroscopy to measure the OH stretches of HOONO and HONO2 to determine the branching ratio. Here, we present the first measurements of the branching ratio as a function of atmospherically relevant temperatures (254 – 333 K) and pressures (50 – 700 torr).