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 C₂ to determine temperature in diamond chemical vapour deposition processes running at atmospheric pressure has been studied. Under atmospheric pressure conditions, the argon interferences 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 C₂ 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.