Production of isotopically pure molecules by dye laser excitation

Employing a low power cw dye laser a weighable quantity (1 mg) of two molecular isotopes was produced in high purity; the two species being sym-tetrazine-¹³C and sym-tetrazine-¹⁵N isomers with the same total mass. The enrichment factor was in excess of 1000. The procedure is based on a previous spectroscopic technique for finding optimum wavelengths for isotopic enrichment in the gas phase. This demonstrates that large enrichment factors are possible even for relatively large molecules with their typically broader spectral features.