Spatially resolved atomic excitation temperatures in CH₄/H₂and C₃H₈/H₂RF discharges by optical emission spectroscopy

Abstract

Spatially resolved optical emission spectroscopy was used to determine the atomic excitation temperature of the capacitively coupled radio-frequency (RF) plasma system. Low pressure plasmas of methane or propane in hydrogen were excited at 13.56 MHz in a parallel plate system. Ar was added as an actinometer. Optical emission lines in the 300-850 nm spectral range were investigated at typical conditions of 100 W RF power, ∼30 mTorr pressure, 20 mm electrode spacing and 50 sccm total flow rate. Two-dimensional intensity profiles of the important species were collected along the vertical and radial axes. The raw radial intensity was transformed into the actual local radiation intensity by Abel inversion. The atomic hydrogen and argon excitation temperature distributions between the power and grounded electrodes were derived from these data and distinct differences were found in methane-and propane-containing plasmas.

Investigation of plasma‐induced chemistry in organic solutions for enhanced electrospun PLA nanofibers

“…The OH signal is possibly coming from the H 2 O impurities in the gas and/or solvents. The observed intensity changes in the atomic argon emission lines in the plasma‐solution system could be due to changes in the electron energy distribution . Additional transition lines from carbon fragments were present in the optical emission spectrum of the plasma‐solution system: a CH band (X 2 ∏←B 2 ∑ − and X 2 ∏←A 2 Δ) at 386.89 and 431.19 nm, respectively, and the Swan system of C 2 lines (X 3 ∏ u ←A 3 ∏ g ) at 473.5, 516.29, 558.11, and 563.26 nm .…”

Propane dissociation in a non-thermal high-pressure nitrogen plasma

“…The experimental points are within these predictions. For an initial propane concentration lower than 2500 ppm, the best agreement is obtained when only reactions (14) and (15) are taken into account. However the agreement can be roughly achieved on the whole range of propane concentration, line denoted A in figure 5 …”

“…Owing to other types of previously developed applications of low pressure plasmas, for example carbon compounds thin films production [14], numerous works have been performed in the past about electron collisions on this hydrocarbon molecule [15][16][17][18], especially on ionisation processes. However, there is a lack of knowledge about dissociation processes of propane, in particular through quenching collisions of the nitrogen metastable electronic states [19,20], in high-pressure and low temperature pulsed discharge plasmas of molecular gases.…”

Amorphous carbon film deposition on the inner surface of tubes using atmospheric pressure pulsed filamentary plasma source

“…Electron impact dissociation of methyl radical ultimately leads to the formation of carbon atom through CH 2 and CH species. The presence of C and CH are confirmed through their characteristic emission ( figure 14) [42][43][44] measured using echelle spectrometer. In addition to the production of molecular argon ion (Ar 2 + ) through termolecular reaction, argon ion (Ar + ) also produces CH 3 + ion through a high probable reaction with methane.…”