Ionization energy inner-level electrons

X-ray energy is far more energetic than that in the ultraviolet range. If an X-ray photon has an energy that exceeds the ionization energy of an electron, absorption of that photon can eject the electron outright. Furthermore, the ejected electrons are from core levels—those closest to the nucleus. In terms of quantum numbers, these levels correspond to n = 1,2, and 3, which are usually referred to with the older shell notation K, L, and M. When an inner-shell electron is ejected, an outer-shell electron "falls" to fill the vacancy and release X-ray photons (fluorescence) in the process as shown in Figure 5.44. 

Extensive discussion on the ionization potentials of 1,2,5-thiadiazole and its derivatives can be found in CHEC(1984) and CHEC-II(1996) <1984CHEC(6)513, 1996CHEC-II(4)355>. Hel photoelectron spectroscopy, inner-shell electron energy loss spectroscopy involving the S2p, S2s, Cls and Nls edges, and Sis synchrotron radiation photoabsorption spectroscopy were used to probe the occupied and unoccupied valence levels of benzothiadiazole 2 <1991MI165>. 

Fig. 2 shows a diagram summarizing the various transitions which can be observed in the Mjjj and My spectra of a metal as well as in the 3 d Auger spectra. The Mjjj and My absorption transitions are shown in Fig. 2a and b the energy of the Mjjj discontinuity corresponds to the transfer of an inner 3p i2 electron to the Fermi level and its shape involves the 6d unoccupied distribution the energy of the My absorption line is exactly that of the 5/" -> SJjyj excitation transition. The My emission is shown in Fig. 2e an inner 3 d i2 hole is created and a 5/electron transits to this hole with the emission of a photon. In the corresponding non-radiative transition, there is simultaneously the 5/ electron transition, and the excitation or ionization of a 5/electron (or 6p or 6 s) (Fig. 2f). The My resonance line is represented in 2c the excited 5/electron drops back to the inner hole the corresponding emission line then coincides with an absorption line. The competing non-radiative transition is shown in 2d this is an Auger transition in the excited atom the final state has only one hole in an outer shell and the configuration is the same as in a photoemission process.

---