Solidification and epitaxial regrowth in surface nanostructuring with laser-assisted scanning tunneling microscope

Abstract

In this work, parallel molecular-dynamics simulation is conducted to study the long-time ͑up to 2 ns͒ behavior of argon crystal in surface nanostructuring with a laser-assisted scanning tunneling microscope. A large system consisting of more than 1 ϫ 10 8 at. is explored. The study is focused on the solidification procedure after laser irradiation, which is driven by heat conduction in the material. Epitaxial regrowth is observed in the solidification. Atomic dislocation due to thermal strain-induced structural damages is observed as well in epitaxial regrowth. During solidification, the liquid is featured with decaying normal compressive stresses and negligible shear stresses. Two functions are designed to capture the structure and distinguish the solid and liquid regions. These functions work well in terms of reflecting the crystallinity of the material and identifying the atomic dislocations. The study of the movement of the solid-liquid interface reveals an accelerating moving speed in the order of 3-5 m / s. The spatial distribution of the moving speed at the solid-liquid interface indicates a nonuniform epitaxial regrowth in space. The bottom of the liquid solidifies slower than that at the edge.

Phase change mechanisms during femtosecond laser pulse train ablation of nickel thin films

“…23 MD simulation is a powerful tool to describe the phase change. 19 In the combined model, the MD simulations substitute the TTM for lattice temperature. 17 The lattice heating by the hot electrons is achieved by scaling the atom velocities with a factor 24…”

Hybrid atomistic-macroscale modeling of long-time phase change in nanosecond laser–material interaction

“…Laser beam absorption in the cell is achieved by exciting the kinetic energy of atoms, which is fulfilled by scaling the velocities of atoms with an appropriate factor. Details of laser beam absorption have been discussed in our previous work [21][22][23][24][25].…”

“…To characterize the volume reduction rate of the liquid, criteria have to be established to distinguish the liquid and solid. In this work, a simple definition of the crystallinity is designed as [21] …”

Plasmonic-enhanced targeted nanohealing of metallic nanostructures

“…In nature, the ability to heal injury increases the survivability and lifetime of most plants and animals. In artificial fields, healing materials after damage or fracture for prolonging their life-span and reducing their costs has a dramatic impact on micro/nano-scopic fields, including biomedicine, [1][2][3][4][5][6] mechanics, [7][8][9][10][11][12] photonics, [13][14][15][16][17][18][19][20][21][22][23] and electronics. [24][25][26][27][28][29][30][31] Healing of microdefects (such as microcracks [32][33][34][35] and microscratches 15,[36][37][38] ) plays an important role in manufacture and maintenance of mechanic, electronic, and photonic micro-devices.…”