Abstract:The conformation of the activated complex often has a great impact on the structure of reaction products. It is an essential piece of information for a better understanding of reaction mechanisms at the molecular level. Among all analytical methods, Raman spectroscopy is perhaps the most convenient to provide such information. To elucidate the molecular mechanisms of the carcinogenesis of polycyclic aromatic hydrocarbons (PAHs), hemoglobin is employed as a model compound to simulate the heme–O2–PAH complex for PAH oxygenation by cytochrome P450. The Raman spectra of benzo[a]pyrene (BaP), a typical carcinogenic PAH, were acquired under different conditions and analyzed. It appears that CH wagging and ring stretching mixed strongly with CH in-plane bending are the most significantly affected vibrations. These vibrations will serve as the basis for future theoretical simulation of the complex configurations.