Characteristic Electron Energy Loss Spectra of Some Alkali Metals and Alkaline Earths

Abstract

The characteristic electron energy loss spectra of Na, K, Ca and Ba have been obtained using the reflection technique and primary electron energies of 800 and 1500 ev. All of the energy losses observed in these metals can be explained as arising from three types of loss mechanism, namely the excitation of plasma-type oscillations, electronic transitions involving excited states and ionization. Plasma excitation energies of 5.87 and 3.87 ev were observed in Na and K respectively, though the first plasma loss peak in the spectra of these metals was displaced from its expected position. The loss peaks in K, Ca and Ba which are considered to be associated with excited states have been related to a previously unexplained series of peaks in Ti, V and Cr, and a peak in Zr. The specific form of the excited state involved cannot be determined from this data alone, but evidence is presented which suggests that an intense broad peak of this nature will occur in the spectra of all the elements which immediately precede or are at the beginning of each of the series of transition metals in the periodic table of elements.