Evidence of decay channel dependent linewidth narrowing in K-shell
photoexcitation spectroscopy of N2 and CO

A. Hempelmann, N. Saito*, F. Heiser, O. Hemmers, K. Wieliczek, J.
Viefhaus, and U. Becker

Fritz-Haber-Institut, Faradayweg 4-6, 14195 Berlin,
Germany;*Electrontechnical Laboratory, Umezono, Tsukuba-shi, Ibaraki,

Vibrationally resolved coincident partial ion yield spectra of N2 and CO
were measured after excitation of the 1s to pi* resonance with
synchrotron radiation. The linewidths of the ion yield spectra becomes
more narrow when the number of ejected electrons increases. The
lifetimes of the singly charged molecular ions N2+ and CO+ are longer
than the natural lifetime of the core excited states measured in
absorption or via total yield.