Basic Research on Laser Isotope Separation by 2-Color IR Multiple Dissociation.

利用TEA CO_2激光器和自由电子激光器（FEL）对BCl_3进行了红外多光子解离和同位素分离实验。得到了以下结果：1)首次用FEL证明了BCl_3的多光子解离和^<10>B和^<11>B的同位素分离。2)测定了激光辐照强度对解离产率的影响。在激光强度超过离解阈值的区域，BCl_3分子在一个CO_2激光脉冲或一个FEL大脉冲下全部离解。3)在BCl_3的振动共振中，当频率向红侧移动时，解离产率最大。BCl_3操作气体压力越低，同位素选择性越大。4)双色红外激光照射可大大提高同位素的选择性。

IR multiphoton dissociation and isotope separation experiments of BCl_3 have been performed by using a TEA CO_2 laser and an free electron laser (FEL). The following results were obtained.1) Multiphoton dissociation of BCl_3 and isotope separation of ^<10>B and ^<11>B using an FEL was demonstrated for the first time.2) Dependences of dissociation yields on laser irradiation intensity were measured. It was found that in the region where the laser intensity exceeds the dissociation threshold all the BCl_3 molecules dissociate for one CO_2 laser pulse or for one FEL macropulse.3) The maximum dissociation yield is obtained for the freqeency shift towards the red side from the vibrational resonance of BCl_3. The lower the operation gas pressure of BCl_3, the larger the isotope selectivity.4) The isotope selectivity is greatly improved by 2-color IR laser irradiation.