1) Nano- and micro- scale thermal transport in solid-state structures 

 

This project focuses on study and control of nano- and micro- scale thermal transport in interfacial, nanostructured, ion irradiated and phase-transformed thermal functional materials by advanced ultrafast laser pulsed & continuum wave time, -frequency & spatial domain thermorelfectance and opto-thermal Raman microscopy technques for advanced energy applications. Phonon-mediated thermal conduction in varios irradiated and phase-transformed metal oxides, carbides, nitrides, alkali halides as well as in novel interfacial and nanostructured materials with phonon hydrodynamics are investigated to validate atomistic, nanoscale (molecular dynamics) and continuum heat propagation models. 

 

2) Nano- and micro- scale mechanics and opto-mechanics of irradiated solids   

 

This project targets micro- and nano- scale depth profiling of elastic, photo-elastic and optical properties of swift heavy ion irradiated and implanted solids by Brillouin scattering microscopy, pico- & nano-second laser ultrasonics and transient grating spectroscopy. The spatial structural distribtion of radiation-induced extended and point defects is quantified and qualified by photoluminescence, Raman and high resolution transmission electron microscopies. Measured elastic properties are employed for validation of DFT models.

 

3) GHz thermo-visco-elastometry of complex polymer nanocomposites and biomaterials  

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We are investigating hypersonic temperature- and stress-dependent visco-elastic properties of polymer nanocomposites, irradiated functional polymers and biomaterials (protein solutions, cornea tissues, mammalian bones and animal flesh tissues, plant leaves, human body fluids) by Brillouin light scattering micro-spectroscopy using scanning 6-pass tandem Fabry-Perot interferometry coupled with confocal microscope and single photon counting and VIPA spectrometer. This project pursues optical sensing for variety of applications ranging from inductrial to biomedical sectors. Using this technique we also investigate phononic band-gap properties of oil-infiltrated polymeric phononic band-gap crystals periodically meso-structured by femtosecond laser-induced two-photon polymerization for potential application in the control of GHz acoustic waves and heat. We have also demonstrated surface plasmon-mediated enhancement of Brillouin light scattering in bulk and on solid surfaces.

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4) Fast melting & ultrasonics in refractory metals 

 

We have developed all-optical technique for automated high-temperature control of thermophysical properties of refractory materials using nanosecond laser pulse-induced heating, melting and ablation and their detection by nanosecond time-resolved spectral radiometry and two-wave mixing photorefractive interferometric laser vibrometry. These techniques aim for laser pulse-based melting & real-time diagnostics of materials suitable for harsh conditions pertinent to nuclear & fusion energy and aerospace applications. We have also conducted MD simulation of solid-to-melt phase transitions in refractory metals under complex stress states.