Laser-Induced Polymeric Film and Aerosol Particle Formations from Gaseous Molecules.

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Solid polymeric materials such as thin films and aerosol particles were produced directly from gaseous organic molecules upon the exposure to an N_2 laser light. From gaseous methyl acrylate (MA), polymeric film was formed selectively on a quartz window of the irradiation vessel. The product yield measured by weighing is proportional to the irradiation time of laser light, and is roughly proportional to the second power of the laser intensity. IR spectrum of the deposited film coincides well with the one of poly(methyl acrylate) commercially available, indicating that radical species is produced by two photon absorption in the vapor phase and also on the surface of the deposited film without decomposing into fragments under laser light irradiation.Upon the exposure to an N_2 laser light, gaseous mixture of MA and acrolein (AC) produced both a solid polymeric film and sedimental aerosol particles. IR spectra of both the deposited film and sedimental particle have bands characteristic of poly(methyl acrylate) and acrolein polymer, indicating that both products are composed of MA and AC polymers. For gaseous mixture of MA and AC, film formation process is more efficient than the aerosol particle formation.Gaseous mixture of MA and carbon disulfide (CS_2) produced mainly sedimental aerosol particles upon the exposure to an N_2 laser light. Sedimental aerosol particles are spherical with a mean diameter of -0.3 mum, and has IR bands characteristic of poly(methyl acrylate), indicating that MA is polymerized into the aerosol produced from CS_2.From this research, we could produce new composite films and aerosol particles directly from gaseous molecules under the irradiation of laser light. Chemical composition and particle diameter were also found to depend on sample pressure, laser intensity, and irradiation time. These findings give us a way to control the physical and chemical properties of new solid materials.