Optical Emission Spectroscopy Study of Premixed C_2H_4/O_2 and C_2H_4/C_2H_2/O_2 Flames for Diamond Growth with and without CO_2 Laser Excitation

摘要

Optical emission spectroscopy (OES) measurements were carried out to study premixed C_2H_4/O_2 and C_2H_4/C_2H_2/O_2 combustion flame for diamond deposition with and without a CO_2 laser excitation. Strong emissions from radicals C_2 and CH were observed in the visible range in all the OES spectra acquired. By adding a continuous-wave CO_2 laser to irradiate the flame at a wavelength of 10.591 urn, the common CO_2 laser wavelength, it was discovered that the emission intensities of the C_2 and CH radicals were increased due to the laser beam induced excitation. OES measurements of the C_2 and CH radicals were performed using different gas combinations and laser powers. The rotational temperatures in the flame were determined by analyzing the spectra of the R-branch of the A~2Δ→X~2Π (0, 0) electronic transition near 430 nm (CH band head). Information obtained from the OES spectra, including the emission intensities of the C_2 and CH radicals, the intensity ratios, and the rotational temperatures, was integrated into the study of diamond deposition on tungsten carbide substrates for mechanism analysis of the laser induced vibrational excitation and laser-assisted diamond deposition.