Experimental and Theoretical Study of the Plasma Chemistry of Ethyl Lactate Plasma Polymerization Discharges

In this work, a new plasma diagnostic method has been used to quantify the plasma-generated species that play a part in the ethyl lactate plasma polymer film deposition. This method has been possible by using the RGA mass spectrometry combined with the in situ FTIR spectroscopy supported by DFT calculations. Ethyl lactate plasma phase can then be qualitatively and quantitatively probed by varying the experimental parameters. More specifically, it has been shown that by increasing the power from 30 to 280 W, the density of ester-bearing species in the plasma strongly decreases and supports the drop of ester content in plasma polymers. Additionally, the temperature of the plasma has been determined by the in situ IR spectroscopy and has revealed a too weak increase (60 K) to affect the fundamental vibrational levels. Our IR spectroscopy approach goes into that direction too.