Analytical application of 2f-wavelength modulation for isotope selective diode laser graphite furnace atomic absorption spectroscopy

Experiences in the analytical application of the 2f-wavelength modulation t echnique for isotope selective atomic absorption spectroscopy in a graphite furnace are reported. Experimental as well as calculated results are prese nted, mainly for the natural lithium isotopes. Sensitivity, linearity, and (isotope) selectivity are studied by intensity modulation and wavelength mo dulation. High selectivities can be attained, however, on the cost of detec tion power. It is shown that the method enables the measurement of lithium isotope ratios larger than 2000 by absorption in a low-pressure graphite tu be atomizer.