Emission of highly excited electronic states of potassium from cryptomelane nanorods

Cryptomelane (KMn 8 O 16 ) nanorods were synthesized, characterized (XRD, Raman spectroscopy, TEM/ SAED) and investigated by species resolved thermal desorption of potassium from the material in the range of 20–620 1 C. The desorbing fluxes of ions, atoms and highly excited electronic states (field ionizable Rydbergstates)weremeasuredusinganioncollector,surfaceionizationandfieldionizationdetectors, respectively, in a vacuum apparatus. The non-equilibr ium emission of potassium Rydberg species (principal quantum number 4 30) strongly depends on the surface posi tive voltage bias with a broad maximum at 1–8 V. The stimulation of Rydberg species emission is discussed in terms of spatial and energetic over- lapping between the electron cloud above the cryptomelane surface and the desorbing potassium ion.