This setup is equipped with femtosecond titanium-sapphire laser (Spectra-Physics Tsunami, Santa Clara, CA, USA) delivering 100 fs pulses at a wavelength of 790 nm with 82 MHz repetition rate. The energy of a single pulse was 15 nJ. The laser beam was then focused by Zeiss Plan-Neofluar 40x/0.75 objective and formed a spot with 1.2 μm in diameter on the sample surface. The beam was attenuated with an acoustic-optical filter to the energy level of 6.25nJ per pulse at the focal plane of the microscope

objective. The investigated samples Selleckchem STI571 were placed onto the stage of the microscope without cover glass. CNT array treatment was achieved by scanning line-by-line at 512 lines per scan resolution. The scan speed was about 145 mm/s. The dimension of the scan area could be varied from 230 × 230 μm to 30 × 30 μm. Zoom factor of the microscope was chosen equal or greater to the required Nyquist criterion to ensure the focal spot overlaps between neighboring lines. Three-dimensional scanning is achieved with a built-in Z-axis drive. The step of Z-axis was chosen to be 1 μm, again to ensure the spatial overlapping of the focal spot between neighboring planes. Results The characteristic morphology and composition of the obtained CNT array

as well as the CNT structure are depicted in Figure 1a,b,c,d,e,f. Figure 1a shows the SEM image of the synthesized dense vertically SGC-CBP30 aligned CNT array. Figure 1b,c shows the TEM images of the synthesized CNTs which are found to be multiwall, with outer diameters of 12 to 70 nm. From Figure 1b, it is seen that some CNTs are filled with nanoparticles (1) in the channels of CNTs and (2) in between their walls. Figure 1d corresponds to the Raman

spectrum collected from the sample which contains 4-Aminobutyrate aminotransferase D peak (approximately 1,358 cm−1) arising from the structural disorder and G peak (approximately 1,584 cm−1) common to all sp2 carbon forms. The ratio of intensities I G/I D = 2.47 testifies that CNTs are well crystallized and have low defect concentration. The XRD pattern in Figure 1e shows that the CNT array contains graphite (002) with a rhombohedral structure [37] (ICDD card no. 75–2078, PCPDFWIN), which is a characteristic of CNTs. Besides, the XRD pattern exhibits a series of peaks corresponding to Fe phase (including carbides): Fe3C and Fe5C2. Analysis of the XRD result reveals that carbide Fe3C with an click here orthorhombic structure (space group Pbnm) dominates over the other phases of nanocomposite (approximately 90%) [32, 38]. The Mössbauer spectrum collected in transmission geometry at room temperature is shown in Figure 1f, and the hyperfine parameters (subspectra) are summarized in Table 1. It has been specified that these states of iron are fcc γ-Fe, bcc α-Fe, and Fe3C. However, the spectrum does not reveal the state of Fe5C2 but instead the doublet of FeC2. This discrepancy can be attributed to the difference in sensitivity between the two methods.