Simulation of the d3Πg-a3Πu system (swan band) of the C2 molecule in atmospheric pressure argon ICP for diagnostic of diamond deposition process

A spectroscopic method using the molecular spectrum of C-2 to determine temperature in diamond chemical vapour deposition processes running at atmospheric pressure has been studied. Under atmospheric pressure conditions, the argon inteferences cannot be ignored without inducing important errors. The precise simulation of emission spectra permits a rigorous line selection and background correction. Systematic comparison has been done with the values of temperature obtained using iron spectrum. The resulting method is fast and easy to implement. The temperatures measured from iron and C-2 spectra are close, suggesting that important difference between excitation and rotational temperatures sometimes quoted in literature could be due, at least partly, to spectroscopic mistakes.