Paper NS-TuP3
Laser Transfer of Organic Molecules through a Liquid Layer

Tuesday, October 16, 2007, 6:00 pm, Room 4C

Previous results of implantation of Coumarin 6 (C6) molecules on a target polymer surface by laser molecular implantation technique showed that the achieved minimum size of dots could be 3 µm in diameter. However, the implantation of organic molecules into conductive organic or inorganic materials on the nanometer scale is one of the challenging problems in materials research that has to be solved. Here, we report the process of laser molecular implantation of pyrene acid and pyrene sublimed molecules onto different materials by generating a laser-induced water channeled jet through a liquid-filled space-gap between the source film and target materials. This process leads to significant reduction in the size of implanted organic molecular dots to a sub-micrometer region on the surface of solid materials such as glass and copper. The pyrene source films were prepared by means of thermal evaporation onto a cover glass with the thickness of about 600 nm. The source film and the target were brought into contact, and the distance between them was filled with liquid. A four nanosecond pulse laser beam was focused on the surface of the source film by special array of lenses, and those photo-excited organic molecules. As a result, the molecules could be ejected from the source film in a form of a plume through a strait path, which was created by laser induced plasma. Later the molecules were implanted onto or into the target materials in the form of dots or rings depending on laser fluence. Those experiments focused on the implantation process of pyrene organic molecules in the submicron region on glass and copper substrates through polar and non-polar liquids. The size of the smallest implanted pyrene acid dots implanted through water and diidomethane layer was estimated to be about 0.4 µm and 0.3 µm at laser fluences of 235 Jcm^-2 and 326 Jcm^-2 , respectively. From fluorescence spectra it was noticed that the implanted molecules did not decompose during the implantation process no matter which liquid filled the gap. In the case of pyrene sublimed molecules it was found that implantation occurs only through a water layer, and, also, that the implanted dots have a very short life time.