| 摘要 |
<p>Selection criteria are disclosed for choosing a coreactant RX that will improve the isotope separation in laser-activated chemical reactions which may proceed by the steps: 1MY + hV¿L? ← ?1MY*¿ (Laser Activation of Isotopic Materials), RX + hV¿L? ← RX?*¿ (Laser Activation of Coreactant), ?1MY* + RX(*)¿ ← (?1MY*:RX(*))| ← 1¿MX + RY (Chemical Exchange Reaction). The step of coreactant activation can be important in some exchange reactions but unnecessary in others. That is for some laser-activated chemical reactions, the second step may be absent. The selection criteria are based on the relative magnitudes of the bond-energies and therefore vibrational frequencies in the molecules 1MY and RX, and the requirements for forming a Vanderwaals-like attachment complex. Also, the upper and lower limit of tolerable thermal (non-laser) reaction speeds are defined. It is shown further that it is necessary to restrict suitable RX candidates to those species which yield 1MX product that does not participate in subsequent chemical reactions which cause isotope scrambling. The employment of a second auxiliary coreactant is recommended in certain cases if its interaction with the complex (?1MY*:RX(*))|¿ will increase the latter's reaction rate and/or if it can scavenge the product 1MX, thereby negating any subsequent isotope scrambling reactions of 1MX. The auxiliary coreactant should not react, or only slowly react, with the reactants 1MY or RX. By application of the selection criteria to UF¿6?, a small group of suitable chemical coreactants are identified which give improved Uranium isotope separations.</p> |
