Accession Number : AD0712309

Title :   INVESTIGATION OF RADIATIVE AND NONRADIATIVE TRANSITIONS IN LASER CRYSTALS.

Descriptive Note : Interim rept. 11 Jun-9 Dec 66,

Corporate Author : RAYTHEON CO WALTHAM MASS RESEARCH DIV

Personal Author(s) : Weber,Marvin J.

Report Date : FEB 1967

Pagination or Media Count : 94

Abstract : 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 f(N) electronic configurations, all reduced matrix elements of the magnetic-dipole operator were computed. The reduced matrix elements of the unit tensor operators U(lambda) required for electric-dipole transitions were also computed for lambda = 2, 4, 6 using L S coupled states for f(1), f(2), and f(3). The relaxation processes for four different fluorescent levels of Eu(3+) 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)

Descriptors :   (*RARE EARTH ELEMENTS, *ELECTRON TRANSITIONS), (*LASERS, RARE EARTH ELEMENTS), EXCITATION, DIPOLE MOMENTS, ATOMIC ENERGY LEVELS, FLUORESCENCE, MAGNETIC PROPERTIES, RELAXATION TIME

Subject Categories : Lasers and Masers

Distribution Statement : APPROVED FOR PUBLIC RELEASE