Lasers and Excited States of Rare Earths

ISBN-13: 9783642666988 / Angielski / Miękka / 2012 / 228 str.

Renata Reisfeld; Christian K. Jorgensen

Opis

The possibility of stimulated light emission was discussed by Einstein in 1917, eight years before the quantum-mechanical description of energy levels of many-electron systems. Though it is imperative to use samples having optical properties greatly different from the stan dard continuous spectrum of opaque objects ("black body" radia tion) it is not always necessary to restrict the study to monatomic entities. Thus, spectral lines can be obtained (in absorption and in emission) from lanthanide compounds, containing from one to thir teen 4f electrons going from trivalent cerium to ytterbium, that are nearly as sharp as the ones from gaseous atoms. However, the presence of adjacent atoms modifies the simple picture of an isolated electron configuration, and in particular, it is possible to pump excited levels efficiently by energy transfer from species with intense absorption bands, such as the inter-shell transitions of other lanthanides and of thallium(I), lead(II) and bismuth(III) or the electron transfer bands of the uranyl ion or other complexes. On the other hand, it is possible to diminuish the mUlti-phonon relaxation (competing with sharp line luminescence) by selecting vitreous or crystalline materials with low phonon energies. Obviously, one cannot circumvent the conservation of energy by lasers, but they may have unprecedented consequences for the future by allowing nuclear fusion of light elements, effects of non-linear optics and time-resolved spectroscopy, besides the more conventional applications of coherent light beams with negligible angular extension."

Spis treści

1. Analogies and Differences Between Monatomic Entities and Condensed Matter.- A. The Configuration 4fq as an Instance of Spherical Symmetry.- B. The “Ligand Field” as Minor Deviations from Spherical Symmetry.- C. Inter-shell Transitions to Empty 5d and 6s Orbitals.- D. Electron Transfer Bands, Including the Uranyl Ion.- References.- 2. Rare-Earth Lasers.- A. Introduction.- B. Spontaneous and Stimulated Emission.- C. Three-level Laser System.- D. Four-level Laser System.- E. Modes of Oscillation.- F. The Threshold of Optical Pumping.- G. Laser Output.- H. Examples of Rare Earth Lasers.- a) Liquid Rare Earth Lasers.- b) Generalities About Solid State Lasers.- c) Relaxation Processes in Solid State Lasers.- d) Crystal Rare Earth Lasers.- e) The Specific Case of Nd3+Crystal Lasers.- f) Laser Emission of Ho3+, Er3+ and Tm3+.- g) High-power Nd3+ Glass Lasers.- h) Nd-doped Glass Ceramic Laser.- i) Lasers from Vapours of Rare-Earth Compounds.- References.- 3. Chemical Bonding and Lanthanide Spectra.- A. The Nephelauxetic Effect and the Photo-electron Spectra.- B. The Intensities and the Hypersensitive Pseudoquadrupolar Transitions.- C. The Chemistry Behind the Judd-Ofelt Parametrization.- References.- 4. Energy Transfer.- A. Transfer Probabilities.- a) Resonance Energy Transfer.- b) Exchange Interaction.- c) Magnetic Interaction.- d) Electrostatic Interaction.- e) Statistical Aspects of Macroscopic Energy Transfer.- B. Migration of Excitation.- C. Inhomogeneous Broadening.- D. Phonon-assisted Energy Transfer.- E. Selected Examples and Suggestions.- a) Donors with Spin-forbidden 3d Transitions.- b) Post-transitional (Mercury-like) Donors with Laporte-allowed Transitions.- c) Electron Transfer Bands in Early Transition Elements as Donors.- d) Energy Transfer from the Uranyl Ion to Lanthanides.- e) Energy Transfer Between Lanthanides.- f) Processes of Infra-red to Visible Up-conversion.- g) Energy Transfer from Organic Ligands to Lanthanides.- h) Energy Transfer from Lanthanides to Other Species.- References.- 5. Applications and Suggestions.- A. The Standard Emission Spectrum of Opaque Objects (in Atomic Units).- B. Induced Thermonuclear Reactions.- C. Cathodoluminescence and Energy Dissipation from Rapid Elementary Particles and Fission Products.- D. Communications and Holography.- E. Geodesy and Trigonometry in the Solar System.- F. Antiferromagnetic Coupling with Adjacent Transition Group Ions.- G. Final Comments on Spectroscopy in Condensed Matter.- References.- 6. Subject Index.- 7. Author Index.