Abstract. The cross sections for the generation of a fluorescence photon pair following photoexcitation of NO, differential with respect to the solid angles of the emission directions of the two photons, have been measured as a function of incident photon energy to investigate superexcited states of NO in the inner-valence range, in particular around the double ionization potential. Superexcited states of NO in the range 25–47 eV have been newly found as resonance peaks in the cross-section curve. We determined that the superexcited states are singly inner-valence excited and multiply excited states of NO. It is remarkable that there exist superexcited states of NO dissociating into neutral fragments even in the range above the double ionization potential at 38.476 eV. A dip in the cross-section curve is observed around 40 eV; the origin is discussed in terms of the decay dynamics of the superexcited states embedded in the double electronic continuum.

Print publication: Issue 22 (28 November 2009)
Received 16 September 2009, in final form 5 October 2009
Published 30 October 2009