title: Experimental and ab initio characterization of HC3N+vibronic structure. II. High-resolution VUV PFI-ZEKE spectroscopy.
abstract: Vacuum-ultraviolet pulsed-field-ionization zero-kinetic-energy photoelectron spectra of X+Π2←XΣ+1 and B+Π2←XΣ+1 transitions of the HC314N and HC315N isotopologues of cyanoacetylene have been recorded. The resolution of the photoelectron spectra allowed us to resolve the vibrational structures and the spin-orbit splittings in the cation. Accurate values of the adiabatic ionization potentials of the two isotopologues (EI/hc(HC314N)=93 909(2) cm-1and EI/hc(HC315N)=93 912(2) cm-1), the vibrational frequencies of the ν2, ν6, and ν7vibrational modes, and the spin-orbit coupling constant (ASO= -44(2) cm-1) of the X+Π2 cationic ground state have been derived from the measurements. Using ab initio calculations, the unexpected structure of the B+Π2←XΣ+1 transition is tentatively attributed to a conical intersection between the A+and B+electronic states of the cation.
authors.affiliation: Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS UMR 8214, University of Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France.
authors.forename: Bérenger
authors.initials: B
authors.lastname: Gans
authors.affiliation: Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS UMR 8214, University of Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Lamarre
authors.affiliation: Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS UMR 8214, University of Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Broquier
authors.affiliation: Service de Chimie Quantique et Photophysique, Université Libre de Bruxelles, CP 160/09, B-1050 Bruxelles, Belgium.
authors.forename: Jacques
authors.initials: J
authors.lastname: Liévin
authors.affiliation: Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS UMR 8214, University of Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France.
authors.forename: Séverine
authors.initials: S
authors.lastname: Boyé-Péronne