Oxygen precipitates were formed in Czochralski-grown silicon samples at different temperatures and for different lenghts of times of heat treatment. Precipitation was evident from infrared(IR) analysis of so treated samples. These samples were irradiated with 2 MeV electrons at near room temperature (310 K). Deep level transient spectroscopy measurements and IR measurements were performed on these samples. The results show directly that a single carbon atom or a carbon-oxygen complex can serve as nucleation centers for the oxygen precipitation.