ROTATIONAL TEMPERATURE-MEASUREMENTS IN HYDROGEN DISCHARGES

An electrodeless capacitive rf discharge operated at 13.56 MHz, which we used previously in diamond deposition experiments, was placed in a specially constructed furnace in order to control the temperature inde pendently of rf power. Methane highly diluted in hydrogen as well as p ure hydrogen were used as process gases. The emitted light from the pl asma was investigated by optical emission spectroscopy. The relation b etween the rotational temperatures determined from the R branch of the G1 Sigma(g)(+) --> B-1 Sigma(u)(+) (0-0) band of molecular hydrogen w ith furnace temperature, rf power and pressure was investigated. From the results we have to conclude, that the assessed rotational temperat ure can be used only as a rough value for the gas kinetic temperature.