INVESTIGATION OF RADIATIVE AND NONRADIATIVE TRANSITIONS IN LASER CRYSTALS.
Interim rept. 11 Jun-9 Dec 66,
RAYTHEON CO WALTHAM MASS RESEARCH DIV
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The calculation of radiative transition probabilities between energy levels of rare-earth ions in crystals is reviewed. Magnetic-dipole, electric-dipole, and electric-quadrupole transitions are treated. Using L S coupled states for fN electronic configurations, all reduced matrix elements of the magnetic-dipole operator were computed. The reduced matrix elements of the unit tensor operators Ulambda required for electric-dipole transitions were also computed for lambda 2, 4, 6 using L S coupled states for f1, f2, and f3. The relaxation processes for four different fluorescent levels of Eu3 in LaF3 were investigated using steady-state and pulsed selective excitation techniques. Different relaxation modes and rates were found for each level both thermal and concentration quenching were studied. Using intermediate coupled states and fluorescence intensity measurements, the spontaneous emission probabilities for magnetic-and electric-dipole radiation were calculated and found to account for a large fraction of the observed lifetimes. The remaining relaxation and temperature and concentration effects are attributed to energy transfer arising from ion-ion interactions and decay by multiphonon emission. A survey is included of possible-rare-earth ions and transitions for lasers operating in the near-ultraviolet spectral region. Author
- Lasers and Masers