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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

Various types of nanotips. Tips generated at 214 fs for 13 MHz at dwell time of 0.5 ms and 16-W average laser power.
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Figure 4: Various types of nanotips. Tips generated at 214 fs for 13 MHz at dwell time of 0.5 ms and 16-W average laser power.

Mentions: Figure 4 shows SEM images of the randomly selected spots from the irradiated target surface with 214-fs laser pulses. As can be seen, the individual and flower-like nanotips are found to be growing on the target surface. A very interesting pattern is observed in terms of the type of nanotips grown according to the pulse width. When the laser pulse width was increased from 214 to 428 fs and 714 fs, only the nanotips formed from the film of molten target material or large droplets were found to be growing on the target, as observed in Figure 5. The formation of such different types of nanotips can be understood by considering the investigation conducted by Breitling et al. on the vapor flow analysis of the plasma created on the aluminum target under ambient atmosphere [22]. Their study revealed that the vapor-plasma expansion is much more like regular mushroom cloud for longer pulses, whereas it is more turbulent for the shorter pulses. This is mainly due to the disturbances caused using much longer propagation length and by nonlinear radiation-gas interactions for short pulses [22].


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)

Various types of nanotips. Tips generated at 214 fs for 13 MHz at dwell time of 0.5 ms 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 4: Various types of nanotips. Tips generated at 214 fs for 13 MHz at dwell time of 0.5 ms and 16-W average laser power.
Mentions: Figure 4 shows SEM images of the randomly selected spots from the irradiated target surface with 214-fs laser pulses. As can be seen, the individual and flower-like nanotips are found to be growing on the target surface. A very interesting pattern is observed in terms of the type of nanotips grown according to the pulse width. When the laser pulse width was increased from 214 to 428 fs and 714 fs, only the nanotips formed from the film of molten target material or large droplets were found to be growing on the target, as observed in Figure 5. The formation of such different types of nanotips can be understood by considering the investigation conducted by Breitling et al. on the vapor flow analysis of the plasma created on the aluminum target under ambient atmosphere [22]. Their study revealed that the vapor-plasma expansion is much more like regular mushroom cloud for longer pulses, whereas it is more turbulent for the shorter pulses. This is mainly due to the disturbances caused using much longer propagation length and by nonlinear radiation-gas interactions for short pulses [22].

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