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SUMMARY:MechE Colloquium: Photothermal systems - from ultrafast nanophoton
 ics to heat oscillations in solar thermal desalination
DTSTART:20231128T120000
DTEND:20231128T130000
DTSTAMP:20260609T204546Z
UID:d6083f8dd277aef67487169436c73b0db9f218687cc236f234b12835
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof Alessandro Alabastri\, Rice University\nAbstract: Photot
 hermal effects refer to the physical phenomena at the base of electromagn
 etic energy conversion into heat. Nanostructures store energy differently 
 upon interaction with radiation\, depending on the considered time scale\,
  system size\, and interacting components. Properly designed nanostructure
 d surfaces confine electromagnetic energy\, making it available as high-en
 ergy electrons and confined fields\, far-field scattered radiation\, heat 
 or thermal radiation. The mechanisms ruling the light-heat conversion proc
 ess in nanostructures and their interplay with surrounding components are 
 crucial for a broad range of applications\, from ultrafast optical manipul
 ation to compact solar-driven desalination systems.\nThe seminar is divide
 d into two main sections. In the first part\, I will discuss how electroma
 gnetic radiation can be funneled in nanoscale structures and the role the 
 inhomogeneous absorption pattern plays in differently shaped nanostructure
 s. In particular\, I will show how\, right after illumination\, this pheno
 menon leads to a space-dependent out-of-equilibrium hot carrier population
  that breaks the optical symmetry of otherwise symmetrical nanostructures.
  The resulting asymmetric hot-carrier time dynamics can be exploited to ma
 nipulate light-matter interaction in the ultrafast regime (<1 ps). Upon el
 ectron-electron scattering\, electron-phonon scattering induces heating\, 
 and I will show how properly designed large-scale ultrathin (~250nm) metas
 urfaces allow extremely large (~GW/m3) and broadband (~90% of solar spectr
 um) dissipated power densities. Regarding broadband absorbers\, I will als
 o discuss how porosity can alter the dissipation pattern in deep subwavele
 ngth regions. \nIn the second part\, I will focus on one large-scale appl
 ication of photothermal effects: solar thermal desalination. A few years a
 go\, we introduced the concept of nanophotonics-enabled solar membrane dis
 tillation (NESMD)\, where solar-driven localized heat drives the distillat
 ion process. The desalination efficiency was increased by redistributing t
 he photon flux incident on the membrane\, suggesting the possibility of re
 ducing the process footprint by utilizing miniaturized optics instead of m
 ore costly and bulky optical concentrators. Recently\, we have analyzed a 
 resonant heat transfer (RHT) mechanism that turns a solar desalination mod
 ule into a class of oscillating thermal devices. We successfully demonstra
 ted an RHT-based solar desalination module capable of delivering up to 20 
 L/m2/day\, paving the way to realizing scalable and sustainable light-driv
 en water purification systems. I will conclude by providing a perspective 
 on the future opportunities and challenges of modular thermal desalination
  systems.\n\n\n\nBiography: Alessandro Alabastri received his BSc (2007) 
 and MSc (2009) in Engineering Physics from Politecnico di Milano specializ
 ing in Nano-Optics and Photonics. In 2009 he completed his Master’s proj
 ect at the Technical University of Denmark\, working on the optical charac
 terization of metamaterials. In 2014 he obtained a Ph.D. in Nanosciences f
 rom the Italian Institute of Technology and the University of Genoa\, work
 ing on computational modeling of plasmonic structures. In 2015 he was Visi
 ting Researcher at Lawrence Berkeley National Laboratory at the Molecular 
 Foundry. He joined Rice University in 2015 as Postdoctoral Fellow (2015-20
 16) and NEWT Postdoctoral Leadership Fellow (2016-2018)\, working on theor
 etical nanophotonics and solar distillation devices. In 2018 he was appoin
 ted Texas Instruments Research Assistant Professor\, and in July 2020\, he
  started his group as a tenure-track Assistant Professor in the Department
  of Electrical Engineering at Rice University. Dr. Alabastri is an expert 
 in nanophotonics and computational modeling of photo-thermal interactions 
 in complex nanostructures. He worked on several aspects of light-to-heat c
 onversion\, exploring the mechanisms to maximize heat dissipation in nanop
 article-based systems. He has realized predictive models of energy-convers
 ion systems such as Photon Enhanced Thermionic Emission devices in collabo
 ration with the European Space Agency and Nanophotonics Enabled Solar Memb
 rane Distillation modules at Rice University.\n 
LOCATION:MED 0 1418 https://plan.epfl.ch/?room==MED%200%201418 https://epf
 l.zoom.us/j/61626448592
STATUS:CONFIRMED
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