Temperature distribution above a heated surface in a CVD reactor with hydrocarbon-containing gaseous mixtures

Pyrolysis of C2H2 and CH4 gases near a heated surface was investigated usin g coherent anti-Stokes Raman spectroscopy (CARS). Gas temperature and hydro carbon density spatial profiles above the surface of deposition were measur ed. Although the measured hydrocarbon density distribution above the surfac e showed a gradual decrease upon approaching the surface, the observed temp erature distribution revealed the presence of a temperature maximum at dist ances of 300-600 mu m from the surface. The appearance of this maximum is e xplained by the release of condensation energy in the region where intensiv e homogeneous nucleation of carbon clusters takes place.