The number density of ground state atomic oxygen (O( 3 P 2 )) measured in an inductively coupled plasma chamber by cavity enhanced absorption

The absolute number density of oxygen atoms in the O( 3 P 2 ) state is determined in an inductively coupled plasma chamber using absorption spectroscopy enhanced by a high finesse cavity with a continuous wave diode laser as the radiation source. At a nominal pressure of 100 mTorr of precursor gas O 2 and 500 W plasma power the O( 3 P 2 ) concentration is found to be (4.8 ± 0.6) × 10 14 cm −3 .