Rydberg ionization spectroscopy#ZEKE

The ZEKE spectroscopy ( ZEKE short for English zero- electron kinetic energy or even zero kinetic energy ) represents a special form of photoelectron spectroscopy, in which only electrons are detected, the ( almost ) have no kinetic energy (zero kinetic energy ).

Operation

The gas to be examined is irradiated with a short laser pulse. After the laser pulse has decayed, the time is awaited. During this time, all the electrons move out with from the examination region. With the aid of an electric field are extracted and measured after a period of all of the remaining electrons. With this method, electrons can be detected at the ionization limit in particular.

Assessment of

Typical dimensions of the study area are in the millimeter range, can be applied in the millisecond range. Further comprising a radial symmetry of the examination region, it is assumed (r = 1 mm), and ionization in the middle thereof. To get out of the study area, therefore, no longer to be measured, an electron with the energy has to travel a distance of 1 mm. In the case of non-relativistic electron applies to the kinetic energy of

And thus

An electron leaves the study area if and only if

It is thus

With, and results

For the given values ​​so only electrons with a kinetic energy are detected.

Benefits of ZEKE spectroscopy

In contrast to the classical photoemission spectroscopy it is not necessary for Zeke spectroscopy to separate the electrons according to their energy. The devices are thus easier. Furthermore, the yield of electrons is much greater, since these normally distributed in all spatial directions. Only a small fraction of electrons of a given energy is thus measured. In the ZEKE spectroscopy, however, all electrons are detected, have the appropriate energy.