Measurement of C2F4Cl2, CCl4, CHF3 and O2 by wavelength modulation laser atomic absorption spectroscopy of excited Cl, F and O in a dc discharge applying semiconductor diode lasers

The concentrations of C₂F₄Cl₂ and CCl₄, CHF₃ and C₂F₄Cl₂, and O₂ have been measured in a dc gas discharge by wavelength modulation laser absorption spectroscopy of excited chlorine, fluorine and oxygen, respectively, applying semiconductor diode lasers. Argon and helium at reduced pressure were used as plasma gases. Preliminary 3σ detection limits of 0.6–1.5 ppb for chlorine compounds by absorption of the Cl 837.60 nm line, about 70 ppb of fluorine compounds by the F 739.87 nm line, and about 20 ppb oxygen molecules by the O 777.18 nm line were found.