Isotope Separation Using Condensation Repression of the Laser Excited Gaseous CHCl₃ Molecules Colliding with a Cold Wall

Cold surface condensation characteristics of vibrationally excited gaseous chloroform (CHCl₃) molecules have been investigated. Continuous-wave CO₂ laser emission lines between 934.9 and 929.0 cm^-1 were used for excitation of the carbon atom dependent binary vibration of the gaseous chloroform molecules mixed with He or N₂ carrier gases. Gas mixtures were subsonically flowed through a coaxial cylindrical irradiation chamber (IC). The cold IC surface escaped fractions (cuts) of the vibrationally excited chloroform were increased more than 15% when natural chloroform molecules, whose ¹²C isotopic abundance is 98.9%, were used with a N₂ carrier gas. With a He carrier gas, however, changes in the cut were not observed. Separations of isotopic chloroform by selective vibrational excitation were also observed with the enrichment factors between 1.01 and 1.15 under certain IC temperature conditions.