Kinetics of Mo atom formation and consumption in UV multiphoton dissociation of Mo(CO)6 at room temperature

• Published in: Physica scripta 2015-11, Vol.90 (12), p.128006
• Main Authors: Eremin, A V, Gurentsov, E V, Musikhin, S A
• Format: Article
• Language: English
• Subjects: atomic resonance absorption spectroscopy; concentration time profile; gas phase; Mo atoms; reaction kinetics
• ISSN: 0031-8949; 1402-4896
• DOI: 10.1088/0031-8949/90/12/128006

This study is devoted to the investigation of molybdenum atom formation and consumption after UV laser pulse photolysis of molybdenum hexacarbonyl vapor diluted by various bath gases. The processes of formation and consumption of Mo atoms were observed using atomic resonance absorption spectroscopy (ARAS) technique at the Mo-I resonance line (λ = 386.41 nm) providing the time profiles of molybdenum atoms concentration in the ground state. The increase of Mo atoms concentration was detected immediately after laser pulse and was determined mainly by spontaneous radiative quenching of excited Mo atoms produced in photolysis of molybdenum hexacarbonyl. It was found that collision quenching with bath gas molecules played a minor role. The following decrease of Mo atoms concentration after a maximum was attributed to the reactions of recombination, cluster formation and other secondary reactions. Based on the experimental data obtained, the kinetic mechanism of Mo atoms formation and consumption in photo-dissociation of Mo(CO)6 was developed. The rate constants of basic reactions responsible for this mechanism were estimated using the frequencies of gas-kinetics collisions or were extracted directly from experimental data by the fitting of measured and calculated time profiles of Mo atoms concentration.