Optical emission spectroscopy (OES) and spectroscopic temperature determination were carried out to study C2H4=C 2H2=O2 flames used for diamond deposition with and without an excitation by a wavelength- tunable CO2 laser. Strong emissions from C2 and CH radicals were observed in the visible range in all the acquired OES spectra. When the flames were irradiated by using a continuous-wave (CW) CO2 laser at a wavelength of 10:591 μm, the emission intensities of the C2 and CH radicals in the flames increased owing to the laser excitation. The CO2 laser was also tuned to a wavelength of 10:532 μm to precisely match the resonant frequency of the CH2-wagging vibrational mode of the C2H4 molecules. OES spectroscopy of the C2 and CH radicals were performed at different laser powers. The rotational temperatures of CH radicals in the flames were determined by analyzing the spectra of the R branch of the AΔΔ→ X2π (0; 0) electronic transition near 430nm. The deposited diamond thin-films were characterized by scanning electron microscopy, stylus profilometry, and Raman spectroscopy. The deposition mechanism with and without the CO2 laser excitation was discussed based on the OES spectral results.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Engineering (miscellaneous)
- Electrical and Electronic Engineering