Glassy carbon layer formed in diamond-like carbon films with femtosecond laser pulses

Ultrafast dynamics of periodic nanostructure formation on diamondlike carbon films irradiated with femtosecond laser pulses

“…The two peaks in a spectrum started to be observed with an increase in R, representing the structural change from DLC to GC. 12,13 We note that, as shown in Fig. 3͑a͒, this structural change is induced with N ϳ 100 around the first peak of R in Fig.…”

“…It is well known, however, that the nanostructure formation with femtosecond laser pulses cannot be explained by the conventional ripple model, and thus the physical mechanism creating such nanostructures is an important subject to study. [5][6][7][8][9][10][11][12][13] In the previous experiments for DLC films, Yasumaru et al 12 and Miyazaki et al 13 have found that the nanostructure formation on the DLC surface is accompanied by the bonding structure change from DLC to glassy carbon ͑GC͒, and that the reflectivity change on the DLC surface is a good measure to monitor the experimental conditions to induce these morphological and bonding structure changes. These experiments suggested that the change in bonding structure may be a key to understanding the detailed process responsible for the nanostructure formation.…”

Nanostructure formation processes in femtosecond laser ablation of thin film surfaces

“…In such interaction of light with materials as the laser processing, the spatial resolution is usually limited to the order of laser wavelength by diffraction limit of light. Despite this well-known limitation, the femtosecond (fs) laser ablation for solid targets has shown that the periodic structures created on the material surface are often much smaller than the laser wavelength λ [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17], being in contrast to the so-called ripples with the period close to λ [18,19]. The characteristic properties of the formation have been studied as functions of laser parameters such as polarization, fluence, wavelength, and superimposed pulse number.…”

Friction Properties of the DLC Film with Periodic Structures in Nano-scale

“…The mechanism of generation of the periodic nano-scale structures has not yet been clarified, but may be new laser ablation without thermal process 3,5,6,7) . The structure size was much smaller than that of well-known ripple structures observed on laser-irradiated material surfaces.…”