Search

The adhesion of the PTFE substrate whose surface was modified by photochemical reaction upon the irradiation of an ArF excimer laser and Xe2* excimer lamp under a hydrazine and ammonia atmosphere was examined by a peel-off test for the sample prepared by jointing the PTFE substrate and a copper plate through chemical adhesives. These surface-modified PTFE samples were improved in adhesive property, which was 7-20 times higher than that of original PTFE. The chemical modification on the surface of PTFE was discussed on the basis of XPS and static SIMS analyses.

We have investigated the laser ablation of UV transparent materials of PTFE, FEP, quartz and sapphire with a femtosecond-pulsed UV laser at the wavelength of 268nm. Upon laser irradiation, a fine etching without debris was obtained on the surfaces of PTFE and quartz. The laser-ablated surfaces were analyzed by optical microscopy. The ablation mechanism is discussed in terms of multi-photon absorption and thermal diffusion induced by a ultra-short pulse of the laser.

We investigated the laser ablation of an elastomer composite with nanosecond- (ns-), picosecond- (ps-) and femtosecond- (fs-) pulsed UV lasers (ns-laser: λ=248nm, τ=30ns; ps-laser: λ=263nm, τ=8ps; fs-laser: λ=248nm, τ=500fs). Upon laser irradiation, a unique microstructure on the surface of the elastomer composite (acrylate polymer) containing carbon black (particle size: 18-30nm) was observed. The laser-ablated surfaces were analyzed by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The formation mechanism is discussed in terms of thermal effects induced by the different pulse durations of the lasers.

We have investigated the photochemical reaction in the external photon field induced with KrF excimer laser (λ=248nm) for the bis(ethynylstyryl)benzene (BESB) films deposited by a molecular beam deposition technique. The cis-cis isomer crystalline films have grown on the KBr (001) substrate without laser irradiation. The laser irradiation to the film surface after and during deposition at the substrate temperature of 25°C caused the cis-to-trans photoisomerization and gave amorphous films due to disordering of the molecular arrangement. On the contrary, the photoisomerized trans-trans isomer crystals were found to be grown upon the irradiation during deposition at the substrate temperature of 60°C. These results indicate that the applied photon field to the molecular beam and the substrate temperatures during deposition play a significant role in thefilm structures.

The formation of radicals on the surface of poly(ethylene naphthalate) (PEN) and poly(ethylene terephthalate) (PET) films after KrF excimer laser ablation was investigated by measurements of electron spin resonance (ESR) and by analyses of surface reaction with a vinyl monomer at a cryogenic temperature. The ESR spectrum of the ablated films in a sealed tube showed a broad peak. Acrylic acid ester and styrene derivatives were immobilized on the ablated and fragment-deposited surfaces through chemical bonds.

Four kinds of amphiphilic aromatic compounds which one might expect to undergo efficient [2+2] or [4+4] photocycloadditions have been prepared for the investigation on photochemical reactions in Langmuir-Blodgett films. The properties of monolayers were very sensitive to molecular structure. The strong interaction of chromophores in LB films showed remarkable shift in electronic spectra.