Selective infrared multiphoton dissociation of molecules in a pulsed gasdynamic flow of small extent

The isotopically selective IR multiphoton dissociation of molecules (here C F3I) in a pulsed gasdynamic flow of small extent (the length of the flow in space is Delta x(fl)less than or equal to 1 cm) is investigated under cond itions such that the entire flow is irradiated by high-intensity IR laser r adiation. The use of a flow of small extent permits achieving high dissocia tion yields of resonantly excited molecules in the entire volume of the flo w and thus to obtain a highly enriched residual gas in one radiation cycle. The method described gives a 400-fold enrichment of the residual gas in th e isotope C-13 when a pulsed molecular flow of CF3I of natural isotopic com position is irradiated by just a single laser pulse. The dissociation yield in this case is practically unity, and the selectivity alpha greater than or equal to 10. (C) 1999 American Institute of Physics. [S1063-7842(99)0050 1-2].