Effect of pressure and pulse length on the isotopically selective photodissociation of freon CF₂Cl₂ under CO₂ laser pulses

When the ¹³C species of CF₂Cl₂ is excited by short TEA-CO₂ laser pulses, the isotopic enrichment of the resultant photodissociation remains constant between 0.25 and 2 Torr CF ₂Cl₂ pressure, whereas excitation of the ¹²C species yields a monotonous decrease of the enrichment with pressure in the same range. These results are compared to those obtained with longer pulses and with the ³²S and ³⁴S species of SF₆.