The dissociation reactions of C2H2+2 dication produced in double photoionization study of acetylene molecules by using 39.0 eV synchrotron radiation energy, have been investigated by coupling photoelectron-photoion-photoion coincidence and ion imaging techniques. The dissociation leading to C2H++H+ products occurs through a metastable dication with a lifetime of 108±22 ns, and a kinetic energy release (KER) distribution exhibiting a maximum at 4.3 eV with a full width at half maximum (FWHM) of about 60%. The reaction leading to CH2++C+ occurs in a time shorter than the typical rotational period of the acetylene molecules (of the order of 10-12 s). The KER distribution of product ions for this reaction, exhibits a maximum at 4.5 eV (FWHM of 28%). The symmetric dissociation, leading to CH++CH+, exhibits a KER distribution with a maximum at 5.2 eV (FWHM of 44%). For the first two reactions the angular distributions of ion products also indicate that the double photoionization of acetylene occurs when the neutral molecule is mainly oriented perpendicularly to the light polarization vector.
DOUBLE PHOTOIONIZATION OF ACETYLENE BY SYNCHROTRON RADIATION
FALCINELLI, Stefano;CANDORI, Pietro;PIRANI, Fernando;ROSI, Marzio;VECCHIOCATTIVI, Franco
2012
Abstract
The dissociation reactions of C2H2+2 dication produced in double photoionization study of acetylene molecules by using 39.0 eV synchrotron radiation energy, have been investigated by coupling photoelectron-photoion-photoion coincidence and ion imaging techniques. The dissociation leading to C2H++H+ products occurs through a metastable dication with a lifetime of 108±22 ns, and a kinetic energy release (KER) distribution exhibiting a maximum at 4.3 eV with a full width at half maximum (FWHM) of about 60%. The reaction leading to CH2++C+ occurs in a time shorter than the typical rotational period of the acetylene molecules (of the order of 10-12 s). The KER distribution of product ions for this reaction, exhibits a maximum at 4.5 eV (FWHM of 28%). The symmetric dissociation, leading to CH++CH+, exhibits a KER distribution with a maximum at 5.2 eV (FWHM of 44%). For the first two reactions the angular distributions of ion products also indicate that the double photoionization of acetylene occurs when the neutral molecule is mainly oriented perpendicularly to the light polarization vector.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.