Table 1 Calculated spectroscopic parameters.
From: Broadband infrared LEDs based on europium-to-terbium charge transfer luminescence
CaS | SrS | |
|---|---|---|
Eu–S equilibrium distances | ||
Eu2+(8S7/2) | 2.876 | 2.974 |
Eu3+(1A1g) | 2.729 | 2.800 |
Difference | 0.147 | 0.174 |
Tb–S equilibrium distances | ||
Tb3+(1A1g) | 2.708 | 2.780 |
Tb2+(1Γ7g/u) | 2.833 | 2.948 |
Difference | −0.126 | −0.169 |
LnS6 breathing mode | ||
Vibrational frequencies | ||
Eu2+(8S7/2) | 286 | 273 |
Tb3+(1A1g) | 306 | 284 |
Mean values | 296 | 279 |
Eu3+(1A1g) | 307 | 286 |
Tb2+(1Γ7g/u) | 277 | 233 |
Mean values | 292 | 242 |
MMCT properties | ||
Equilibrium energy | 19,968 | 20,403 |
Equilibrium Qet | 0.428 | 0.548 |
Diabatic energy barriers for hopping | ||
Eu2+ Tb3+ ↔ Eu3+ Tb2+ | ||
1Γ8g 1A1g → 1A1g 1Γ7g/u | 3406 | 3742 |
1Γ8g 1A1g ← 1A1g 1Γ7g/u | 748 | 1602 |
Diabatic energy barriers for Non-radiative decay MMCT | ||
Eu3+ Tb2+ ↔ Eu2+ Tb3+ | ||
1A1g 1Γ7g/u → 8S7/2 3A1g | 786 | 94 |
