Laser‐Induced Softening of Lattice Vibrations

Zijlstra, Eeuwe S.; Garcia, Martín E.

doi:10.1002/9783527633418.ch19

Cited by 5 publications

(2 citation statements)

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“…In other words, we model the ultrashort laser pulse excitation by setting the electronic temperature T e instantaneously to a high, constant value. The interested reader can find more details and further theoretical justifications of this approach in [35].…”

Section: Physical Picture Of An Ultrashort Laser Pulse Excitationmentioning

confidence: 99%

Mechanical properties of boron-nitride nanotubes after intense femtosecond-laser excitation

Bauerhenne¹,

Zijlstra²,

Kalitsov³

et al. 2014

Nanotechnology

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A femtosecond-laser pulse constitutes an unconventional tool to manipulate solids and nanostructures, for it may excite materials in a transient nonthermal state with hot electrons and atoms close to their initial temperature. Here we study the Young's modulus and the electronic band gap of a (5, 0) zigzag boron-nitride nanotube (BNNT) after an ultrashort laser pulse excitation using density functional theory, where the effect of a femtosecond-laser pulse is modelled by an instantaneous rise of the electronic temperature. At room temperature, before the laser pulse, we obtain a Young's modulus of 763 GPa, which decreases with increasing electronic temperature. For the band gap we find a value of 2.26 eV at room temperature, which increases with increasing electronic temperature and equals 3.28 eV at 28 420 K. We note that conventional means decrease the band gap of BNNTs and that a femtosecond-laser pulse is, to the best of our knowledge, the first tool that increases it. For comparison, we also present results for a (9, 0) zigzag BNNT.

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Section: Physical Picture Of An Ultrashort Laser Pulse Excitationmentioning

confidence: 99%

Mechanical properties of boron-nitride nanotubes after intense femtosecond-laser excitation

Bauerhenne¹,

Zijlstra²,

Kalitsov³

et al. 2014

Nanotechnology

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“…Surface waves and, in general, localized waves play a significant role across a wide spectrum of scales ranging from seismic to nano scales [6][7][8][9][10]. Besides the canonical scattering by an edge in continuous media [11], and equivalent problems involving elastic, acoustic and electromagnetic waves, the scattering associated with discontinuities or steps/serrations on crystal surfaces also gives rise to related challenges [12][13][14][15] under different types of environmental conditions. In general, the identification and nature of surface wave modes is in itself an important question and there is a long history of different approaches.…”

Section: Introductionmentioning

confidence: 99%

Scattering of surface waves by inhomogeneities in crystalline structures

Sharma

2024

Proc. R. Soc. A.

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In current scientific and technological scenarios, studies of transmittance of surface waves across structured interfaces have gained some wind amidst applications to metasurfaces, electronic edge-waves, crystal grain boundaries, etc. The results presented in the present article shed a light on the influence of material inhomogeneities on propagation of surface waves. Within the framework of classical mechanics, an analogue of the Gurtin–Murdoch model is employed where elastic properties on surface are assumed to be distinct from bulk. Restricting to scalar waves on prototype square lattice half-plane, particles on considered structured surface have piecewise-constant mass and surface force-constants across an interfacial point. Particles in bulk lattice interact with nearest neighbours in a way that involves unequal force-constants parallel to surface versus normal to it. A surface wave band exists for such lattice structure wherein the waveform decays exponentially inside the half-plane. A formula for surface wave transmittance is given based on an exact solution on half-plane, and, thus, previous work (Sharma & Eremeyev 2019 Int. J. Eng. Sci. 143 , 33–38 ( doi:10.1016/j.ijengsci.2019.06.007 )) is extended. An explicit expression for fraction of energy influx leaked via bulk waves is a highlight. Included are graphical results for several illustrative values of surface structure parameters.

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