An experimental investigation characterizing the microscopic dynamics following the Coulomb explosion of intermediate (C3H6O2+)* molecular dications produced by double photoionization of the propylene oxide has been reported. The double photoionization experiment has been performed at the “Circular Polarization” beamline of the Elettra Synchrotron Facility of Trieste (Italy) using linearly polarized light in the 18-37 eV energy range, coupling ion imaging and pothoelectron-photoion-photoion coincidence techniques with the “Angle-Resolved-PhotoEmission-Spectroscopy” end station, already employed in previous experiments. Preliminary data show six different two-body fragmentation processes. The main recorded two body fragmentation channels yield C2H4+ + CH2O+, and C2H3+ + CH3+ product ions (66.70% and 18.70%, respectively). Minor two-body dissociation processes producing CH2+/C2H4O+, CH3+/C2H3O+, O+/C3H6+, OH+/C3H5+ ion pairs were also detected. Energy thresholds for the formation of different ionic products, the related branching ratios, and the kinetic energy released (KER) distribution of fragment ions are measured at different photon energies. In particular the total KER distribution for the dissociation channel producing CH3+/C2H3O+ final ions clearly indicates a bimodal behavior, depending on the two possible microscopic mechanisms for the two-body fragmentation of (C3H6O2+)* dication following its Coulomb explosion. In fact, in the case of such a fragmentation reaction two different isomers of the C2H3O+ final ion can be formed: the linear CH3-CO+ acetyl cation and the cyclic [CH2-CH-O]+ oxiranyl cation. Further experimental and theoretical investigations should clarify the relative importance of such different microscopic pathways. These new experimental data are mandatory information to unravel the physical chemistry of the elementary processes induced by the interaction of photons, with simple relevant chiral species, being the propylene oxide the first chiral molecule recently discovered in interstellar cloud Sagittarius B2.
Coulomb Explosion and Fragmentation Dynamics of Propylene Oxide Dication
Falcinelli Stefano
2018
Abstract
An experimental investigation characterizing the microscopic dynamics following the Coulomb explosion of intermediate (C3H6O2+)* molecular dications produced by double photoionization of the propylene oxide has been reported. The double photoionization experiment has been performed at the “Circular Polarization” beamline of the Elettra Synchrotron Facility of Trieste (Italy) using linearly polarized light in the 18-37 eV energy range, coupling ion imaging and pothoelectron-photoion-photoion coincidence techniques with the “Angle-Resolved-PhotoEmission-Spectroscopy” end station, already employed in previous experiments. Preliminary data show six different two-body fragmentation processes. The main recorded two body fragmentation channels yield C2H4+ + CH2O+, and C2H3+ + CH3+ product ions (66.70% and 18.70%, respectively). Minor two-body dissociation processes producing CH2+/C2H4O+, CH3+/C2H3O+, O+/C3H6+, OH+/C3H5+ ion pairs were also detected. Energy thresholds for the formation of different ionic products, the related branching ratios, and the kinetic energy released (KER) distribution of fragment ions are measured at different photon energies. In particular the total KER distribution for the dissociation channel producing CH3+/C2H3O+ final ions clearly indicates a bimodal behavior, depending on the two possible microscopic mechanisms for the two-body fragmentation of (C3H6O2+)* dication following its Coulomb explosion. In fact, in the case of such a fragmentation reaction two different isomers of the C2H3O+ final ion can be formed: the linear CH3-CO+ acetyl cation and the cyclic [CH2-CH-O]+ oxiranyl cation. Further experimental and theoretical investigations should clarify the relative importance of such different microscopic pathways. These new experimental data are mandatory information to unravel the physical chemistry of the elementary processes induced by the interaction of photons, with simple relevant chiral species, being the propylene oxide the first chiral molecule recently discovered in interstellar cloud Sagittarius B2.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
