AbstractCollisional activation spectra were used to characterize isomeric ion structures for [CH5P]+˙ and [C2H7P]+˙ radical cations and [C2H6P]+ even‐electron ions. Apart from ionized methylphosphane, [CH3PH2]+˙, ions of structure [CH2PH3]+˙ appear to be stable in the gas phase. Among the isomeric [C2H7P]+˙ ions stable ion structures [CH2PH2CH3]+˙ and [CH2CH2PH3]+˙/[CH3CHPH3]+˙ are proposed as being generated by appropriate dissociative ionization reactions of alkyl phosphanes. At least three isomeric [C2H6]+ ions appear to exist, of which \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 3} - \mathop {\rm P}\limits^{\rm + } {\rm H = CH}_{\rm 2} $\end{document} could be identified positively.

The potential of photodissociation spectra for the structure elucidation of gaseous organic ions is demonstrated using isomeric C5H8+· and C4H4+· ions as example.

AbstractThe photodissociation of [C4H5N]+˙ ions generated by ionization of pyrrole (1), allyl cyanide (2), crotonitrile (3), cyclopropyl cyanide (4) and methacrylonitrile (5) has been studied using ion beam techniques. At least four different stable ion structures have been distinguished, which is in contrast to earlier CAD studies. In addition it has been shown that [C2H3N]+˙ fragment ions formed by dissociative ionization of the same precursors have structures which are distinct from that of ionized acetonitrile.

Photodissociation cross-sections of a variety of small heteroatom-containing even- and odd-electron ions have been determined in the wavelength range from 340 to 680 nm using a krypton ion laser as light source. In this wavelength range, no photodissociation has been observed for even-electron ions while, on average, the maximum cross-sections for photodissociation of odd-electron ions are smaller than those reported for hydrocarbon ions. With the exception of methanol, the photodissociation spectra are not in conflict with the photoelectron spectra. The photodissociation spectra give information on the constitution and electronic structure of organic ions.