Metastable atomic energy states

Figure 5. Resonance ionization spectra of the elements Re, Fe, Ni, and Mo. For each element the wavelength of the frequency-doubled dye output was scanned while focussing the mass spectrometer on the most abundant atomic ion of the element. Each wavelength dependent peak represents ion formation from a specific groTond state or metastable atomic energy level (ll).

If the work function is smaller than the ionization potential of metastable state (see. Fig. 5.18b), then the process of resonance ionization becomes impossible and the major way of de-excitation is a direct Auger-deactivation process similar to the Penning Effect ionization a valence electron of metal moves to an unoccupied orbital of the atom ground state, and the excited electron from a higher orbital of the atom is ejected into the gaseous phase. The energy spectrum of secondary electrons is characterized by a marked maximum corresponding to the... 

The noble-gas metastable atoms Ne through Xe are 3P2 0 atoms, so that more than one potential-energy curve governs the scattering, even with S-state collision partners. Because spin-orbit interactions are large whereas weak van der Waals interactions imply only weak coupling to the... 

Let us now return to equation (150). An excited but metastable atom such as (Hg 63P0) must either radiate or lose energy by collision to return to the ground state. The same is true of a diatomic molecule. In both instances the term collision is broadly used and might include the formation of an intermediate complex which would ultimately dissociate to ground state molecules. 

High speed of cooling of the deposit material during the process of film formation, sufficient for the preparation of metal films in metastable or amorphous state (usually these states appeared when the kinetic energy of the depositing atoms was higher than 10 eV). 

In view of the fundamental nature of the system more extensive and more precise data would be highly desirable as a test for bound state QED calculations. With the exception of the 1S-2S energy difference measurement, which is limited in precision by the laser wavelength measurement, all present experiments suffer from low statistics due to the small number of Ps atoms. It seems therefore worthwile discussing recent advances of increased Ps production and in parti-cular methods to populate the metastable 2 Sj state, which could serve as a basis for excited state spectroscopy. While laser excitation of states above n=2 from the ground state requires wavelengths between 205 nm (Lg) and 182 nm (ionization limit), which are very difficult to obtain with sufficient power, the corresponding wave-... 

---