Comparison of the photodissociation dynamics of alkyl nitrites in the A and B absorption bands

RECIO, PEDRO; CACHON, JAVIER; RUBIO-LAGO, LUIS; MARGGI, SONIA; MAHECHA, GENESYS; PINO, GUSTAVO A.; BAÑARES, LUIS

Simposio; 30th edition of the International Symposium on Molecular Beams; 2023

Alkyl nitrites (R-ONO, R=CH3, n-C3H7, t-C4H9) have been widely studied due to the efficient photodissociation and formation of NO fragment.1,2 The absorption spectra of all these molecules present two bands. A first band characterized by a clear vibronic structure, and a second more intense band which extends to the VUV energy reagion.2,3 In this work, three different alkyl nitrites where studied, CH3ONO, n-C3H7ONO, and t-C4H9ONO, so a comparison of the hydrocarbon chain on the photodissociation dynamics could be made.4 The study was performed in the two absorption bands (A and B) independently. Pump-probe experiments using nanosecond laser pulses in combination with velocity map imaging detection of NO by 1+1 REMPI were carried out. The results in the A band show a shift in the kinetic energy distributions as higher vibrational states for a fixed rotational quantum number J=19.5 of the NO fragments were detected. By comparing the three molecules, a larger shift in energy is also present, a displacement previously observed in the studies of alkyl halogen molecules.4 Several differences in the shape of the kinetic energy distributions, and in the angular distributions, were also detected. Meanwhile, the B band show a parallel transition in contrast to the perpendicular transitions observed in the A band. In this case, several contributions could be observed for each of the measurements performed.