Laser Femtosecond Opto-Acoustic System For Elastic And Thermal Properties Measurement Of Nanocomposites
Abstract
The aim of this proposal is to acquire instrumentation to build state-of-the art Femtosecond Laser Opto-acoustic System to investigate thermal and elastic properties of nanocomposites (nano rods and fibers, different 2D nanomaterials: free standing and attached to a surface). The spectrometer is going to be based on femtosecond pump-probe time resolved reflectivity measurements. It is well known that reflectivity of metallic surfaces depends on subsurface temperature of the material. When ultrafast laser pulses are absorbed by materials, after very fast relaxation processes, due to electron-electron, electron-phonon and phonon-phonon scattering temperature is established at surface layers of the material. The subsurface temperature, then, due to migration of electrons and phonons from excited area is decreasing. We have to mention that these migration processes of non-equilibrium carriers could be ballistic, diffusive or quasidiffusive. By detecting time resolved surface reflectivity we can measure surface temperature changes of metallic materials at sub picosecond and femtosecond time scale (timedomain thermoreflectance) . This will allow us to determine how fast ÒheatÓ carriers are leaving the excited area; investigate phonon scattering processes and measure heat diffusion constants, as well as anisotropy of it.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Sep 20, 2018
- Source ID
- W911NF1710498
Entities
People
- Sergey Avanesyan
Organizations
- Army Contracting Command
- Fisk University
- Office of the Secretary of Defense