Ruby, spectroscopic properties

Solid-State Lasers Radiative Properties of Ruby Crystals Spectroscopic Properties of CdSe Nanocrystals... 

The spectroscopic properties of ruby have been studied for over one hundred years starting with the work by Becquerel (1867), who excited ruby with sunlight. He claimed that the properties of this crystal were intrinsic, but later it was shown that the color as well as the luminescence of ruby are due to the Cr ion that plays the role of an optical center in the nonabsorbing AI2O3 host. Only much later these properties could be explained by considering the influence of the surroundings of the Cr center on its energy levels (crystal-field theory). For a summary of ruby history the reader is referred to ref. 1. 

The choice between T2 and E is, of course, not a choice of groundstate. The spectroscopic properties discussed here are, as far as absorption goes, determined by the vibrational amplitude of the A2 groundstate. By a vertical projection (satisfying the Franck-Condon principle) it may hit E at lowest energy (as is the case without ambiguity in ruby) or the beginning of the broad band due to T2. The observed one-sided halfwidths 6 (typically 800 to 1800 cm" are compatible with the force-constant of the... 

Because chemical and structural properties of natural and artificial gems are very similar in this case, the possibilities of Raman and LIBS methods are rather limited. It was found that another laser-based techniques could be very effective for rapid spectroscopic discrimination between natural and synthetic emeralds, rubies, and alexandrite (Armstrong et al. 2000a,b). The first one is DRIFTS (Diffuse Reflectance Fourier Transformed Infra-Red Spectroscopy)... 

The first optical laser, the ruby laser, was built in 1960 by Theodore Maiman. Since that time lasers have had a profound impact on many areas of science and indeed on our everyday lives. The monochromaticity, coherence, high-intensity, and widely variable pulse-duration properties of lasers have led to dramatic improvements in optical measurements of all kinds and have proven especially valuable in spectroscopic studies in chemistry and physics. Because of their robustness and high power outputs, solid-state lasers are the workhorse devices in most of these applications, either as primary sources or, via nonlinear crystals or dye media, as frequency-shifted sources. In this experiment the 1064-mn near-infrared output from a solid-state Nd YAG laser will be frequency doubled to 532 nm to serve as a fast optical pump of a raby crystal. Ruby consists of a dilute solution of chromium 3 ions in a sapphire (AI2O3) lattice and is representative of many metal ion-doped solids that are useful as solid-state lasers, phosphors, and other luminescing materials. The radiative and nonradiative relaxation processes in such systems are important in determining their emission efficiencies, and these decay paths for the electronically excited Cr ion will be examined in this experiment. 

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