Uranyl complexes fluorescence

It should also be remarked that uranyl complexes tend to emit a bright green fluorescence under UV irradiation, from the first excited state. This is used by geologists both to identify and to assay uranium-bearing minerals in deposits of uranium ores. 

Very recently, Addleman et al. described a high-pressure cell for the study of TRLIF of uranyl complexes in supercritical CO2 (21). A schematic of the optical cell is shown in Figure 3. The cell has two perpendicular optical paths that are both orthogonal to the SCF flow, allowing absorption, fluorescence, and Raman measurements. The cell body was machined from stainless steel with an internal volume of 0.3 ml. The cell windows were made of 2-mm-thick synthetic... 

The hydrolysis of the uranyl(VI) ion, UO " 2> has been studied extensively and begins at about pH 3. In solutions containing less than lO " M uranium, the first hydrolysis product is the monomeric U02(OH)", as confirmed using time-resolved laser induced fluorescence spectroscopy. At higher uranium concentrations, it is accepted that polymeric U(VI) species are predominant in solution, and the first hydrolysis product is then the dimer, (U02)2(0H) " 2 (154,170). Further hydrolysis products include the trimeric uranyl hydroxide complexes (U02)3(0H) " 4 and (1102)3(OH)(154). At higher pH, hydrous uranyl hydroxide precipitate is the stable species (171). In studying the sol-gel U02-ceramic fuel process, O nmr was used to observe the formation of a trimeric hydrolysis product, ((U02)3( -l3-0)(p.2-0H)3) which then condenses into polymeric layers of a gel based on the... 

It is certainly very remarkable that uranyl platinocyanide should fail to respond to the stimulus of ultra-violet light or to radium radiations. Both the uranyl and the platinocyanide groups can confer the property of fluorescence upon salts containing them, yet when they both occur in the same complex, there is no sign of fluorescence. 

At present, luminescence determination methods are available for almost all elements of the periodic table (Fig. 3). Most extensively used are methods whereby fluorescent, more rarely phosphorescent, complexes of elements with organic ligands are obtained. Many methods utilize the native luminescence of lanthanoides (III), uranyl, mercury-like and other ions in crystallophosphors and complexes with inorganic and organic ligands and also chemiluminescence. 

The Purex process is another process that requires continuous monitoring of uranyl ion [24]. This has been achieved by exciting the fluorescence of uranyl ion in nitric acid medium at 337 nm using a nitrogen laser. Phosphoric acid is additionally added because it complexes the ion, enhances its fluorescence, and thereby lowers the detection limit. 

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