INFIQC   05475
INSTITUTO DE INVESTIGACIONES EN FISICO- QUIMICA DE CORDOBA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Vibrational Relaxation of Carbon Monoxide after the electronic excitation of (ClCO) 2.
Autor/es:
MATIAS BERASATEGUI; LUCÍA LANFRI; MAXI A. BURGOS PACI; SALAS JUNANA; GUSTAVO A ARGÜELLO
Lugar:
Mendoza
Reunión:
Encuentro; 9th International meeting on photodynamics and related aspects.; 2016
Institución organizadora:
Universidad de Tandil
Resumen:
P { margin-bottom: 0.21cm; direction: ltr; color: rgb(0, 0, 0); widows: 2; orphans: 2; }A:link { color: rgb(0, 0, 255); }Thefragmentation of a bound molecule through absorption of one or morephotons is called photodissociation. The electromagnetic energy ofthe light beam is converted into internal energy of the molecule andif the transferred energy exceeds the binding energy of the weakestbond the molecule will irreversibly break apart. Photodissociationis a fantastic field for studying the internal dynamics of polyatomicmolecules. In the last decades the interest on the study of primaryphotolysis processes of halogenated organic molecules has increasedbecause of its relevance in atmospheric chemistry. In particular,time resolved spectroscopy studies allows to understand differentaspects about photodissociation mechanisms.Aspecific experimental setup was used in order to detect the timeresolved infrared fluorescence of ro-vibrationally excited carbonmonoxide (CO*) originated from the photolysis of (XCO)2-typemolecules (where X can be either Cl or F).Suitsand Lee 1,2studied the emission of CO* after the photolysis (ClCO)2atdifferent wavelengths namely, 193, 235 and 248 nm. They concludedthat the energy balance for photolysis at 193 nm suggests that itsmechanism of dissociation differ from that at 248 nm. This work aimedto study the ro-vibrational relaxation of CO* after the photolysis of(XCO)2at266 nm using Nd:YAG laser operating with the proper harmonicgenerator module.Thecharacterization of the photodissociation process was achieved by theuse of a FTIR spectrometer together with a mercury lamp emitting at266 nm. The information obtained with this experiments along with theprevious results, allowed us to propose a possiblemechanismfor the (XCO)2 photolysisat this wavelength.Thestudy of time-solved IR fluorescence confirmed the presence of CO*.For this purpose, a gas filter containing ?cold? CO was placedbetween the emission source and the detector showing that calculatedautoquenchingconstant is bigger than the one obtained without the filter. Thisresult indicates that CO* ()is generated with the photolysis.Sinceit is known that there exist a dependence between the relaxation timeand the pressure of the quencher, a collisional quenching study wasperformed with O2,CO2and CO as quenchers. It was found that the energy-transfer processwas very efficient for CO and that for CO2other relaxation process take place, being CO2better quenching than CO. For pressures bigger than 10 mbar, reactiveprocesses are observed generating CO2asone of the products which acts as quencher.