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Study of nanostructure growth with nanoscale apex induced by femtosecond laser irradiation at megahertz repetition rate.

Patel NB, Tan B, Venkatakrishnan K - Nanoscale Res Lett (2013)

Bottom Line: We have recently developed this unique technique to grow leaf-like nanostructures with such interesting geometry without the use of any catalyst.It was found to be possible only in the presence of background nitrogen gas flow.We observed a clear transformation in the kind of nanotips that grew for the given laser conditions.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Aerospace Engineering, Ryerson University, Victoria Street, Toronto, ON M5B 2K3, Canada. tanbo@ryerson.ca.

ABSTRACT
Leaf-like nanostructures with nanoscale apex are induced on dielectric target surfaces by high-repetition-rate femtosecond laser irradiation in ambient conditions. We have recently developed this unique technique to grow leaf-like nanostructures with such interesting geometry without the use of any catalyst. It was found to be possible only in the presence of background nitrogen gas flow. In this synthesis method, the target serves as the source for building material as well as the substrate upon which these nanostructures can grow. In our investigation, it was found that there are three possible kinds of nanotips that can grow on target surfaces. In this report, we have presented the study of the growth mechanisms of such leaf-like nanostructures under various conditions such as different laser pulse widths, pulse repetition rates, dwell times, and laser polarizations. We observed a clear transformation in the kind of nanotips that grew for the given laser conditions.

No MeSH data available.


Related in: MedlinePlus

Nanotip growth under different femtosecond laser irradiation dwell times. SEM images of nanotip growth stages at the 8-MHz repetition rate for dwell times of (a) 0.1, (b) 0.25, and (c) 0.50 ms for 214 fs and 16-W average laser power.
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Figure 7: Nanotip growth under different femtosecond laser irradiation dwell times. SEM images of nanotip growth stages at the 8-MHz repetition rate for dwell times of (a) 0.1, (b) 0.25, and (c) 0.50 ms for 214 fs and 16-W average laser power.

Mentions: The dwell time study was performed for 214-fs pulse width and various repetition rates. Figure 7 shows the SEM images of the glass target machined at dwell times of 0.1, 0.25, and 0.5 ms for the 8-MHz repetition rate. The growth steps of the nanotips are clearly evident from these three images. As a result, it is obvious from Figure 7 that the growth of these nanostructures is dependent on the dwell time as much as on other laser parameters. For example, at 0.1 ms, the plasma has very little vapor content resulting in the redeposition of the droplets on the target surface and the growth of stem for the nanotips, as seen in Figure 7a. Once the stem growth has started, the continuous redeposition of vapor condensates from plasma back to the surface provides the building material for tips to grow. At 0.25-ms dwell time, the plasma has just enough building material for the tips to start growing in a nanoscale to a micrometer length; the number of tips present on surface also increased. When the dwell time is further increased to 0.50 ms, the nanoscale tips grew to the length of 1 to 2 μm as well as their population increased on the target surface.


Study of nanostructure growth with nanoscale apex induced by femtosecond laser irradiation at megahertz repetition rate.

Patel NB, Tan B, Venkatakrishnan K - Nanoscale Res Lett (2013)

Nanotip growth under different femtosecond laser irradiation dwell times. SEM images of nanotip growth stages at the 8-MHz repetition rate for dwell times of (a) 0.1, (b) 0.25, and (c) 0.50 ms for 214 fs and 16-W average laser power.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3643873&req=5

Figure 7: Nanotip growth under different femtosecond laser irradiation dwell times. SEM images of nanotip growth stages at the 8-MHz repetition rate for dwell times of (a) 0.1, (b) 0.25, and (c) 0.50 ms for 214 fs and 16-W average laser power.
Mentions: The dwell time study was performed for 214-fs pulse width and various repetition rates. Figure 7 shows the SEM images of the glass target machined at dwell times of 0.1, 0.25, and 0.5 ms for the 8-MHz repetition rate. The growth steps of the nanotips are clearly evident from these three images. As a result, it is obvious from Figure 7 that the growth of these nanostructures is dependent on the dwell time as much as on other laser parameters. For example, at 0.1 ms, the plasma has very little vapor content resulting in the redeposition of the droplets on the target surface and the growth of stem for the nanotips, as seen in Figure 7a. Once the stem growth has started, the continuous redeposition of vapor condensates from plasma back to the surface provides the building material for tips to grow. At 0.25-ms dwell time, the plasma has just enough building material for the tips to start growing in a nanoscale to a micrometer length; the number of tips present on surface also increased. When the dwell time is further increased to 0.50 ms, the nanoscale tips grew to the length of 1 to 2 μm as well as their population increased on the target surface.

Bottom Line: We have recently developed this unique technique to grow leaf-like nanostructures with such interesting geometry without the use of any catalyst.It was found to be possible only in the presence of background nitrogen gas flow.We observed a clear transformation in the kind of nanotips that grew for the given laser conditions.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Aerospace Engineering, Ryerson University, Victoria Street, Toronto, ON M5B 2K3, Canada. tanbo@ryerson.ca.

ABSTRACT
Leaf-like nanostructures with nanoscale apex are induced on dielectric target surfaces by high-repetition-rate femtosecond laser irradiation in ambient conditions. We have recently developed this unique technique to grow leaf-like nanostructures with such interesting geometry without the use of any catalyst. It was found to be possible only in the presence of background nitrogen gas flow. In this synthesis method, the target serves as the source for building material as well as the substrate upon which these nanostructures can grow. In our investigation, it was found that there are three possible kinds of nanotips that can grow on target surfaces. In this report, we have presented the study of the growth mechanisms of such leaf-like nanostructures under various conditions such as different laser pulse widths, pulse repetition rates, dwell times, and laser polarizations. We observed a clear transformation in the kind of nanotips that grew for the given laser conditions.

No MeSH data available.


Related in: MedlinePlus