Masaki Hada

The film thickness and surface damage layer of vapor‐deposited L‐leucine amino acid films irradiated with Ar cluster ion beams were characterized by PSC _R A ellipsometry. The damaged layer on the surface of the L‐leucine film irradiated with Ar cluster ion beam was quite thin, less than 1 nm in thickness. In contrast, films irradiated with Ar monomer ion beam have changed into totally different films. The ellipsometry method also allowed accurate measurements of the sputtering yield from the L‐leucine film irradiated with Ar cluster ion beams at nm‐order resolution. These results suggested that with proper analysis, the optical method of ellipsometry enables estimation of the surface damage layer and measurement of sputtering yield of organic films irradiated with cluster ion beams. Copyright © 2010 John Wiley & Sons, Ltd.

The lattice motion and displacement of atoms in the unit cell in vanadium dioxide (VO2) grown on c-Al2O3 were characterized by static and time-resolved x-ray diffraction (XRD) measurements. The monoclinic-tetragonal phase transition of the VO2 unit cell and the twist motion of vanadium atoms in the unit cell were observed. The time-resolved XRD measurements were performed in air using a tabletop high-repetition femtosecond laser. The results obtained from the time-resolved XRD measurements suggested that the unit cell of the low-temperature monoclinic VO2 transformed into the high-temperature tetragonal phase extremely rapidly (within 25 ps); however, the atoms in the unit cell fluctuated or vibrated about the center of the tetragonal coordinates, which abated within $\sim${}100$\hskip0.3em${}ps. Thus, the time-resolved XRD measurements of the Bragg angle, intensity, and width of the diffraction lines simultaneously revealed the phase transition of VO2 and the atomic motion in the unit cell.