Femtosecond Laser Melting of Graphite and Diamond

1989 ◽  
Vol 157 ◽  
Author(s):  
D. H. Reitze ◽  
H. Ahn ◽  
X. Wang ◽  
M. C. Downer
Keyword(s):  
Phase Transition ◽  
Liquid Metal ◽  
Femtosecond Laser ◽  
Pyrolytic Graphite ◽  
Highly Oriented Pyrolytic Graphite ◽  
Laser Melting ◽  
Liquid Carbon ◽  
Time Resolved ◽  
High Reflectivity

ABSTRACTFemtosecond time-resolved reflectivity measurements performed on highly oriented pyrolytic graphite (HOPG) and diamond elucidate the nature of the phase transition from solid to liquid carbon. In HOPG, we find that a high-reflectivity phase lasting as long as 10 ps appears when the surface is irradiated with pulse fluences in excess of 0.13 J/cm2, the critical fluence for melting. This transforms within 30 ps into an equilibrium low-reflectivity phase lasting hundreds of ps, similar to behavior observed in picosecond reflectivity experiments. The results suggest the occurrence of a two-step phase transition (graphite -> liquid metal -> liquid insulator) when HOPG is excited above the critical fluence. Similar results are obtained with diamond.

scholarly journals Femtosecond laser-driven shock synthesis of hexagonal diamond from highly oriented pyrolytic graphite

2009 ◽  
Vol 165 ◽  
pp. 012019 ◽  
Author(s):  
Tomokazu Sano ◽  
Kengo Takahashi ◽  
Osami Sakata ◽  
Masayuki Okoshi ◽  
Narumi Inoue ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Pyrolytic Graphite ◽  
Highly Oriented Pyrolytic Graphite ◽  
Hexagonal Diamond

Femtosecond Laser Synthesis of Polymorphic Diamond from Highly Oriented Pyrolytic Graphite

2007 ◽  
pp. 2349-2352
Author(s):  
Tomokazu Sano ◽  
Kengo Takahashi ◽  
Akio Hirose ◽  
Osami Sakata ◽  
Masayuki Okoshi ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Pyrolytic Graphite ◽  
Highly Oriented Pyrolytic Graphite ◽  
Laser Synthesis

Femtosecond Laser-induced Crystallization in As-deposited Ge1Sb2Te4 Films

2003 ◽  
Vol 803 ◽  
Author(s):  
Qin F. Wang ◽  
Lu P. Shi ◽  
Su M. Huang ◽  
Xiang S. Miao ◽  
Kai P. Wong ◽  
...  
Keyword(s):  
Phase Transition ◽  
Femtosecond Laser ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Time Resolved ◽  
Whole Process ◽  
Thermal Phase Transition ◽  
Thermal Phase ◽  
Time Resolved Imaging ◽  
Induced Crystallization

ABSTRACTTime resolved imaging has been used to investigate the whole process of the crystallization induced by intense 130 femtosecond laser pulses in as-deposited Ge1Sb2Te4 films. With an average fluence of 24mJ/cm2 a transient non-equilibrium state of the excited material is formed within 1 picosecond. The results are consistent with an electronically induced non-thermal phase transition.

Femtosecond Laser Synthesis of Polymorphic Diamond from Highly Oriented Pyrolytic Graphite

2007 ◽  
Vol 561-565 ◽  
pp. 2349-2352 ◽  
Author(s):  
Tomokazu Sano ◽  
Kengo Takahashi ◽  
Akio Hirose ◽  
Osamu Sakata ◽  
Masayuki Okoshi ◽  
...  
Keyword(s):  
Shock Wave ◽  
Laser Pulse ◽  
Femtosecond Laser ◽  
Laser Irradiation ◽  
Femtosecond Laser Pulse ◽  
Basal Plane ◽  
Pulse Width ◽  
Pyrolytic Graphite ◽  
Highly Oriented Pyrolytic Graphite ◽  
X Ray

We synthesized polymorphic diamond directly from highly oriented pyrolytic graphite (HOPG) using femtosecond laser driven shock wave without catalyst. A femtosecond laser pulse (wavelength: 800 nm, pulse width: 120 fs, intensity: 2×1015 W/cm2) was irradiated onto the HOPG surface in air. Crystalline structures of HOPG after the laser irradiation were analyzed using the synchrotron X-ray at the BL13XU in the SPring-8. We found that the hexagonal diamond exists in the HOPG which was irradiated by the femtosecond laser normal to the basal plane.

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