Photofragmentation of cyanogen upon carbon and nitrogen K-shell excitation by partial ion yield experiments

Abstract

Abstract. Partial ion yield spectroscopy was used to study fragmentation processes in cyanogen after C 1s and N 1s photoexcitation. The interpretation of the core excitation spectrum mostly follows literature, but the high resolution has in some cases allowed a more detailed assignment. Using the fact that in Rydberg states there is an intensity increase as the fragmentation process becomes more extensive compared to valence orbitals, we have been able to distinguish resonances with valence and Rydberg character. Furthermore, we have been able to assign features in the ionization continuum as arising from double excitations or shape resonances, by observation of the suppression of anion yield at shape resonances. Photofragmentation of cyanogen upon K-shell excitation by partial ion yield2

Jahn-Teller coupling and fragmentation after core-shell excitation in CF4investigated by partial-ion-yield spectroscopy

“…In the case of F 2 + , rearrangement naturally involves heavier atoms. We have reported similar cases of intramolecular rearrangement, such as formation of O 2 + after C 1s core excitation in formic acid [29], and N 2 + after C 1s core excitation in cyanogen [38]. Formation of F 2 + was also found after F 1s core excitation in BF 3 [33].…”

Photofragmentation of BF3on B and FK-shell excitation by partial ion yield spectroscopy

“…We note that the Rydberg region is much more prominent in the anion yield. We have reported this effect in other systems [33] and attributed it to unstable final states reached after spectator decay which fragment easily and produce anions as well as cations. The other major difference is the behavior at threshold.…”

“…Breaking of an H-X bond and formation of another bond during photofragmentation is likely due to the high mobility of the proton, and such processes have been observed in several systems: formation of H [19]. Rearrangements involving heavier atoms are more surprising, although we have reported recently the formation of O + 2 after C 1s core excitation in formic acid [19], and N + 2 after C1s core excitation in cyanogen [33]. In all these examples, intramolecular rearrangement was shown to be helped by vibrational excitation and resonant processes.…”

“…Examples of intramolecular atomic rearrangement following core excitation are numerous in cases where a hydrogen atom is involved. The breaking of an H-X bond and formation of another bond during photofragmentation is likely due to the high mobility of the proton, and such processes have been observed in several systems: formation of H [19], and N + 2 after C 1s core excitation in cyanogen [33]. In all these examples, intramolecular rearrangement was shown to be helped by the vibrational excitation and resonant processes.…”