Measurement of rotational temperature and dissociation in N2O glow discharges using i n s i t u Fourier transform infrared spectroscopy

The technique of in situ Fourier transform infrared (FTIR) absorption spectroscopy has been used to determine rotational temperatures and the extent of dissociation of N2 O in a radio-frequency (rf) glow discharge. Measurements were made at 0.65 cm−1 resolution on 13.56-MHz plasmas at 500 mTorr, with an input flowrate of 40 sccm, and powers of 10 and 30 W. Temperature and dissociation information estimates are based upon analysis of P branch rotational lines of the 2ν1 harmonic and ν1 +ν3 combination band of the molecule. Line intensities are corrected for instrument-induced distortion. Under the conditions investigated, rotational temperatures are between 335 and 420 K, and dissociation ranges from 45% to 75%. Both rotational temperature and dissociation increase with rf power.