Gikan H. Takaoka

Surface Processing and Modification of Polymers by Water Cluster Ion Beam

A water cluster ion beam was irradiated on a poly(methyl methacrylate) (PMMA) surface to examine the possibility of applying the water cluster ion beam technique to the surface processing and modification of polymers. The sputtering yields of PMMA substrates irradiated with water cluster ion beams increased with acceleration voltage and dose of the water cluster ion beam. The threshold acceleration voltage of sputtering was approximately 3 kV. The X‐ray photoelectron spectroscopy (XPS) analysis of the PMMA surface irradiated with the water cluster ion beam suggested the degradation of the PMMA side chains. The XPS spectrum of the surface of the sputtered particle catcher at 45° backward direction showed approximately the same shape as the XPS spectrum of the PMMA surface irradiated with the water cluster ion beam.

Interaction between water cluster ions and mica surface

Water cluster ion beams were irradiated on mica surfaces to investigate the interaction between molecular cluster ions and a mica surface. The contact angle of the mica surface increased with increasing dose of the water cluster ion beam, but the increase in the contact angle was smaller than that induced by an ethanol cluster ion beam. The surface roughness also increased with increasing dose of the water cluster ion beam, whereas the intensity of K 2p x-ray photoelectron spectroscopy peaks decreased with increasing dose of the water cluster ion beam. The decrease in the number of potassium atoms together with the increase in the surface roughness may be the causes of the increase in the contact angle.

Irradiation effects of fragment ions of tetradecane on glass surfaces

Vapors of tetradecane (C₁₄H₃₀) were ionized by electron bombardment. The generated fragment ions such as C₃H₇, C₆H₁₃, and C₁₂H₂₅ ions were separated and accelerated towards glass substrates. The acceleration voltage was adjusted between 1.5 kV and 9 kV. The fluence was 4.0 × 10¹⁶carbon atoms/cm². Thin films were deposited on the glass substrates by C₃H₇- and C₆H₁₃-ion irradiation at an incident energy of 0.42 keV per carbon. Raman spectra measurements showed that DLC films were formed by C₃H₇- and C₆H₁₃-ion irradiation with the film thickness being larger in case of C₃H₇. On the contrary, for C₁₂H₂₅-ion irradiation, the glass substrate surface was sputtered at an incident energy of 0.42 keV per carbon. Chemical sputtering occurred by surface reactions of hydrogen and carbon with silicon and oxygen atoms. In addition, the surface characteristics of glass substrates irradiated by C₃H₇, C₆H₁₃ and C₁₂H₂₅ ions were investigated.