Excitonic and electron-hole processes in NaCl and NaCl : Ag crystals underconditions of multiplication of electronic excitations

The excitation spectra of a and a emissions of self-trapped excitons (3.4 e V and 5.4 eV, respectively) as well as the excitation spectra of 5.17 eV lu minescence of Agi impurity centres were measured in NaCl and NaCl:Ag crysta ls using synchrotron radiation of 5-38 eV. Fast and slow components of thes e emissions were detected. An analysis of the differences in the excitation spectra measured at 8 and 295 K allowed us to separate the excitonic and e lectron-hole (e-h) mechanisms of the multiplication of electronic excitatio ns. A photon of 17-19 eV forms an e-h pair and a secondary exciton, while t he absorption of a 21-27 eV photon causes the creation of two e-h pairs. Us ing luminescent and photoelectric methods, it was shown that a 2p3s Na+ cat ion exciton, formed at the absorption of a 33.4 eV photon, decays with the creation of an anion exciton with a 3p hole component and two e-h pairs. Th ree e-h pairs are formed after the absorption of a 31 eV photon by a chlori ne ion.