22 января, 2016 
Pokraskin After absorption of electrons or high-energy photons (e. g. X-ray quanta) impinging on the phosphor material, secondary charge carriers, i. e. electron-hole pairs, are generated in the lattice. The electron-hole pairs thermalize, eventually leading to band gap excitations. After thermalization, the excitation is transferred to an activator (or sensitizer), resulting in emission. For each absorbed electron or high-energy photon, a large number of electron-hole pairs will be generated. Each electron-hole pair can give rise to emission of one photon on the activator ion.
Robbins has treated these processes more quantitatively [5.225]. A comparison of predicted and experimentally obtained efficiencies is given in Table 5.20. Quite good agreement is observed.
Tab. 5.20: Energy efficiencies of luminescent materials obtained on excitation with high-energy particles. «the is the maximum calculated efficiency, nexp is the energy efficiency observed experimentally.
|
Phosphor |
^the |
^exp |
|
CsI:Tl |
0.14 |
0.14 |
|
ZnS:Ag |
0.25 |
0.20 |
|
ZnS:Cu |
0.21 |
0.17 |
|
CaS:Ce |
0.16 |
0.22 |
|
CaS:Mn |
0.15 |
0.16 |
|
La2O2S:Eu |
0.12 |
0.11 |
|
Y2O3:Eu |
0.07 |
0.08 |
|
YVO4:Eu |
0.07 |
0.07 |
5.5.5
Опубликовано в рубрике 