Knowledge Bank

A resonance in the four-photon ionization spectrum of naphthalene at 470 nm has been found. This has been assigned to a two photon transition, to a g state lying at 42 500 $cm-1$. A resonance at this same energy was seen previously by Compton et al.,$\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$ in a threshold electron impact spectrum. The possible importance of this state in the radiationless de activation of the one-photon-allowed states in this region will be discussed.