On the Plasma Chemistry of an RF Discharge Containing Aluminium Tri‐Isopropoxide Studied by FTIR Spectroscopy

Abstract

International audienceIn Ar and Ar/N2 radio frequency (RF) discharges with admixtures of aluminium tri-isopropoxide (ATI) the fragmentation of this metal-organic precursor was studied by means of Fourier Transform Infrared (FTIR) spectroscopy using an optical long path cell providing an optical length of l= 17.2 m. The experiments were performed in an asymmetric capacitively coupled process plasma at a frequency of f= 13.56 MHz and at pressure values in the range of p= 1 - 10.5 Pa. The discharge power was chosen between P= 10 - 100 W. Using FTIR spectroscopy the evolution of the concentrations of ATI and of six stable molecules, CH4, C2H2, C2H4, C2H6, CO and HCN, was monitored under flowing conditions at gas flows of Φtotal= 0.5 - 14.5 sccm in the discharge. The concentrations of the reaction products were measured to be between 2 x 1012 molecules cm−3 as e.g. found for C2H4 and C2H6, and 5 x 1013 molecules cm−3, as e.g. in the case of CO. In the plasma a complete dissociation of the precursor ATI was found at a power value of about P= 80 W independent on the admixture of Ar or N2. The fragmentation efficiency (FE) of the reaction products which originate from the ATI molecules ranges between 0.2 and 4 x 1016 molecules J−1 while the fragmentation rate (FR) reached up to 2.5 x 1018 molecules s−1. The multi component detection ability of the spectrometer served to analyse the carbon balance of the by-product formation. For all experiments, the carbon balance never exceeded 25%. Therefore, in the plasmas the majority of the provided carbon is most likely deposited at the reactor walls or forms dust particles or higher molecular CxHy. The conversion efficiencies (CE) of the produced molecular species ranges between 0.1 x 1015 molecules J−1 for C2H4 and 5 x 1015 molecules J−1 for C2H6 depending on the discharge conditions of the RF plasma

On the Reduction of Gas‐Phase Naphthalene Using Char–Particles in a Packed–Bed Atmospheric Pressure Plasma

“…To compare experimental results of different reactor geometries and different kinds of discharges the specific energy deposition, SED, which quantifies the deposited energy in the gas volume is defined as in [8,11,13] …”