Laser photoionization separation of isotopes, isobars, and nuclear isomers

4 Laser photoionization separation of isotopes, isobars, and nuclear isomers 

When the first tunable dye lasers made their appearance late in the 1960s (see Stuke 1992), suggestions were put forward as to the use of resonance stepwise ionization for separating isotopes on the basis of isotope shifts in atomic spectra (Letokhov 1969). Following the first successful experiments on the selective ionization of Rb atoms and their isotopes (Ambartzumian et al. 1971), programs were initiated in a number of countries on laser separation of uranium isotopes ( U/ U) by a method that came to be known as the atomic-vapor-laser-isotope-separation (AVLIS) technique (Paisner 

1988 Robieux 2000). The start of these programs was rather fast but premature. It is only now, 30 years later, now that tunable solid-state lasers pumped by semiconductor laser array are available, that the realization of industrial-scale AVLIS facilities looks much more realistic. 

The general scheme of laser photoionization separation of isotopes looks simple enough. It includes several successive processes  

Production of vapor from the solid-phase working element. This vapor contains a natural mixture of isotopes. In the case of high-melting elements, for example, uranium and gadolinium, use is made of electron-beam vaporization. Low-melting metals, such as ytterbium, are heated in an oven. 

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