Ein experimenteller Beitrag zu der durch langsame Primärelektronen ausgelösten Sekundärelektronenemission

Abstract

The energy distribution of secondary electrons emitted from a highly degassed polycristalline Pt surface was investigated as a function of low energy (V _p ) primary electrons 5<V _p <150eV. The measurements were carried out in an UHV of better than 10⁻¹⁰ mm Hg.

The dependence of the numberN ^(Ev) _S of secondary electrons of a fixed energyE _v (3<E _v <12eV) on the energyV _p of the primaries (=isochromates) is studied.

A lot of observations can be detected:

• I. The exit depth of true secondary electrons is strongly dependent of their energy.

• II. Isochromates for the various energiesE _v are investigated in two energy ranges:

• a) 5<V _p <40eV:

• 1. By a suitable linear transformation procedure of both abscissa and ordinate a congruence of all isochromates in a certainV _p region is obtained.

• 2. The slope of the curve in the linear region as a function of secondary energyE _v gives a step-shaped function.

• 3. A threshold energy of secondary electron emission as postulated byShulman andMiakinin cannot be verified with this experiment.

• b) 40<V _p <120 eV:

The isochromates obtained in this energy region show a small but precisely detectable periodic contribution with a periodic length ¯λ which is dependent on the secondary energyE _v .