Trace isotopic analysis by double resonance ionization with cw-lasers and graphite furnace atomization

Two high-resolution, single-frequency dye lasers and a cw CO2 laser have been used to saturate photoionization of atoms generated by a graphite furnace. Isotopic selectivities of greater than 105 have been observed in the double-resonance excitation to Rydberg states, and coupling laser selectivity with a quadrupole mass spectrometer yields isotopic abundance sensitivities in excess of 1010. Instrumental detection limits of ∼ 10-17 grams have been demonstrated. (author)