There are many possible outcomes from these reactions depending on the electron translational kinetic energy (electron temperature). The measurement of this parameter in RF plasma source by Langmuir probe method can alter the electromagnetic fields into the discharge which provoke changes in its properties. Moreover continuous hydrocarbon containing plasma exposure progressively may reduces the precision of the probe and shorten its useful lifetime. Spectroscopy in the visible spectral region can give a wealth of information on the atomic or ionic processes in the plasma. This measurement is not affected by RF fields, do not contaminate the plasma, require little or no maintenance