Editing Einsteinium (section)

===Organoeinsteinium compounds===
Einsteinium's high radioactivity has a potential use in [[radiation therapy]], and organometallic complexes have been synthesized in order to deliver einsteinium to an appropriate organ in the body. Experiments have been performed on injecting einsteinium [[citric acid|citrate]] (as well as fermium compounds) to dogs.<ref name="h1579" /> Einsteinium(III) was also incorporated into β-diketone [[Chelation|chelate]] complexes, since analogous complexes with lanthanides previously showed strongest UV-excited [[luminescence]] among metallorganic compounds. When preparing einsteinium complexes, the Es{{sup|3+}} ions were 1000 times diluted with Gd{{sup|3+}} ions. This allowed reducing the radiation damage so that the compounds did not disintegrate during the 20 minutes required for the measurements. The resulting luminescence from Es{{sup|3+}} was much too weak to be detected. This was explained by the unfavorable relative energies of the individual constituents of the compound that hindered efficient energy transfer from the chelate matrix to Es{{sup|3+}} ions. Similar conclusion was drawn for americium, berkelium and fermium.<ref>{{cite journal|last1=Nugent|first1=Leonard J.|last2=Burnett|first2=J. L.|last3=Baybarz|first3=R. D.|last4=Werner|first4=George Knoll|last5=Tanner|first5=S. P.|last6=Tarrant|first6=J. R.|last7=Keller|first7=O. L.|title=Intramolecular energy transfer and sensitized luminescence in actinide(III) .beta.-diketone chelates|journal=The Journal of Physical Chemistry|volume=73|pages=1540–1549|date=1969|doi=10.1021/j100725a060|issue=5}}</ref>

Luminescence of Es{{sup|3+}} ions was however observed in inorganic hydrochloric acid solutions as well as in organic solution with di(2-ethylhexyl)orthophosphoric acid. It shows a broad peak at about 1064 nanometers (half-width about 100&nbsp;nm) which can be resonantly excited by green light (ca. 495&nbsp;nm wavelength). The luminescence has a lifetime of several microseconds and the quantum yield below 0.1%. The relatively high, compared to lanthanides, non-radiative decay rates in Es{{sup|3+}} were associated with the stronger interaction of f-electrons with the inner Es{{sup|3+}} electrons.<ref>{{cite journal|last1=Beitz|first1=J.|last2=Wester|first2=D.|last3=Williams|first3=C.|title=5f state interaction with inner coordination sphere ligands: Es{{sup|3+}} ion fluorescence in aqueous and organic phases|journal=Journal of the Less Common Metals|volume=93|pages=331–338|date=1983|doi=10.1016/0022-5088(83)90178-9|issue=2}}</ref>