Laser-induced versus shock wave induced transformation of highly ordered pyrolytic graphite

Extinction of ferromagnetism in highly ordered pyrolytic graphite by annealing

We report that the ferromagnetism of highly ordered pyrolytic graphite (HOPG) samples as measured by hysteretic magnetization loops can be diminished and eventually extinguished with sufficiently long high vacuum anneals at temperatures on the order of 2300 !C. Concomitant with the extinction of ferromagnetism, we observe an annealinduced increase in grain size (accompanied by possible edge rec...

Nonlinear Optical Absorption of Carbon Nanostructures Synthesized by Laser Ablation of Highly Oriented Pyrolytic Graphite in Organic Solvents

In this study, Highly Oriented Pyrolytic Graphite was ablated in various polar and nonpolar solvents by Q-switched neodymium: yttrium-aluminum-garnet laser (wavelength=1064 nm, frequency=2 kHz, pulse duration=240 ns). Then, the products were examined using Scanning Electron Microscopy and UV-Vis spectroscopy. The images showed that different carbon structures such as cauliflower-like structures...

Experimental Studies on Plasmon Resonance of Ag Nanoparticles on Highly Ordered Pyrolytic Graphite (HOPG)

On pressure impulse of a laser-induced underwater shock wave

We experimentally examine a laser-induced underwater shock wave paying special attention to the pressure impulse, the time integral of the pressure evolution. Plasma formation, shock-wave expansion and the pressure in water are observed simultaneously using a combined measurement system that obtains high-resolution nanosecond-order image sequences. These detailed measurements reveal a distribut...

Investigation of Shock Wave Interaction Using Laser-induced Iodine Fluorescence

Detailed measurements of flow behavior have been taken in a rarefied ‘slip-flow’ regime hypersonic flow (Mach 12) over a sharp edged flat plate with a circular-cylindrical appendage designed to produced shock wave interactions. The flat plate is presented parallel to the wind tunnel freestream to generate a weak shock which impinges on the nearly-normal cylinder bow shock wave. Tests were condu...