Fast growth of diamond crystals in open air by combustion synthesis with resonant laser energy coupling

Fast growth of diamond crystals in open air was achieved by combustion synthesis with resonant laser energy coupling. A premixed C₂H ₄/C₂H₂/O₂ gas mixture was used as precursors for growth of diamond crystals. Through the resonant excitation of the CH₂ wagging mode of the ethylene (C₂H₄) molecules using a CO₂ laser tuned at 10.532 m, high-quality diamond crystals were grown on silicon substrates with a high growth rate at ~139 m/h. Diamond crystals with a length up to 5 mm and a diameter of 1 mm were grown in 36 h. Sharp Raman peaks at 1332 cm^'1 with full width at half-maximum (fwhm) values around 4.5 cm^'1 and distinct X-ray diffraction spectra demonstrated the high quality of the diamond crystals. The effects of the resonant laser energy coupling were investigated using optical emission spectroscopy.