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22 mars-2 avr. 2021 Les Houches (France)
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Résumé des coursLecture 1 & 2
Coherent phonon photogeneration processes in solids
Speaker: Pascal Ruello Keywords: Laser-matter interaction, electron-phonon coupling, optoacoustics; picosecond acoustics. Summary: In this lecture, we will discuss the generation processes of coherent phonons with ultrafast light pulses. This will be the core of the lectures. Some more recent research directions will be discussed at the end. We will mainly discuss the coherent phonon frequency ranging from GHz to THz. The basics of optical properties of solids will be briefly reminded first. Then we will discuss the different electron-phonon coupling mechanisms for both optical and acoustic phonons photogeneration with a particular focus on acoustic phonon. For that, the out-of-equilibrium carriers dynamics will be described (two-temperature model, Boltzmann equation). We will discuss, for instance, the generation of coherent phonons with visible light (NIR-VIS-NUV), i.e. eV photon [1,3]. This will include the deformation potential mechanism (for both optical and acoustic phonons), the thermoelastic process (for acoustic phonon), the inverse-piezoelectric effect (for acoustic phonon) and the stimulated Raman-Brillouin process (optical-acoustic phonon). Different situations will be discussed in semiconductors [4], topological insulators [5], and ferroic materials [6], to cite a few. As a more recent research direction, we will also discuss the generation of coherent phonon with ultrashort THz pulses i.e. meV photon) leading to optical phonon generation (IR active mode) and acoustic phonons [7]. Finally, by combining time-resolved optical methods and time-resolved X-ray diffraction [8], we will illustrate how it is possible to disentangle the photogeneration and the photodetection processes, and then how it is possible to evaluate more precisely the efficiency of the conversion of the light energy into the mechanical energy (optoacoustics), that we cannot access with full optical method only.
1. C. Thomsen, H. T. Grahn, H. J. Maris, and J. Tauc, Surface generation and detection of phonons by picosecond light pulses, Phys. Rev. B 34, 4129 (1986). 2. P. Ruello and V.E. Gusev, Physical mechanisms of coherent acoustic phonons generation by ultrafast laser action. Ultrasonics, 2015. 56: p. 21-35. doi.org/10.1016/j.ultras.2014.06.004. 3. V. Gusev and A. Karabutov, Laser Optoacoustics (AIP, New York, 1993). 4. Baldini, E.; Dominguez, A.; Palmieri, T.; Cannelli, O.; Rubio, A.; Ruello, P.; Chergui, M. Exciton control in a room temperature bulk semiconductor with coherent strain pulses Science Advances, 2019, 5, eaax2937, DOI:10/ggq6zb 5. Weis, M., K. Balin, R. Rapacz, A. Nowak, M. Lejman, J. Szade, and P. Ruello, Ultrafast light-induced coherent optical and acoustic phonons in few quintuple layers of the topological insulator Bi2Te3. Phys. Rev. B, 2015. 92(1). doi.org/10.1103/PhysRevB.92.014301 6. Lejman, M., G. Vaudel, I.C. Infante, I. Chaban, T. Pezeril, M. Edely, G.F. Nataf, M. Guennou, J. Kreisel, V.E. Gusev, B. Dkhil, and P. Ruello, Ultrafast acousto-optic mode conversion in optically birefringent ferroelectrics. Nature Communications, 2016. 7. doi.org/10.1038/ncomms12345 7. A. Levchuk, B. Wilk, G. Vaudel, F. Labbé, B. Arnaud, K. Balin, J. Szade, P. Ruello, and V. Juvé, Coherent acoustic phonons generated by ultrashort terahertz pulses in nanofilms of metals and topological insulators, Phys. Rev. B 101, 180102(R) (2020) doi.org/10.1103/PhysRevB.101.180102 8. V Juvé, R Gu, S Gable, T Maroutian, G Vaudel, S Matzen, N Chigarev, S Raetz, VE Gusev, M Viret, A Jarnac, C Laulhé, AA Maznev, B Dkhil, P. Ruello, Ultrafast light-induced shear strain probed by time-resolved x-ray diffraction: Multiferroic as a case study, Phys. Rev. B, 102, 220303(R), (2020). _________________________________________________________________________________ LECTURE 3
(I)Time-domain Brillouin scattering: theoretical backgrounds and applications for nanoscale imaging and materials characterizationSpeaker: Vitali E. Gusev Keywords: photoacoustics; optoacoustics; laser ultrasound; time-domain Brillouin scattering; picosecond acoustic interferometry; imaging; microscopy; vibrations of nanolayers and nanostructures Summary: Time-domain Brillouin scattering (TDBS), also known as picosecond acoustic interferometry, is an experimental technique that uses ultrafast lasers for generation and detection of nanometer-scale coherent acoustic pulses with picosecond scale time duration. Detection involves interfering two weak probe light pulses: one scattered by the acoustic nanopulse propagating in transparent materials, and one reflected from various interfaces of the sample. Transient optical reflectivity recorded by a photodetector, as the acoustic nanopulse propagates, contains information on local acoustical, optical, and acousto-optical parameters of the material. TDBS imaging is based on Brillouin scattering and has potential to provide all information that researchers in materials science, physics, chemistry, biology etc., could get with classic frequency-domain Brillouin scattering. It can be viewed as a replacement for Brillouin microscopy in all investigations where nanoscale spatial resolution is required. TDBS has been already applied for imaging of nanoporous films, ion-implanted semiconductors/dielectrics, grain boundaries, metal-epoxy interfaces, vegetable and animal cells, texture in polycrystalline materials, temperature distributions in liquids, and for monitoring the transformation of nanosound caused by absorption, diffraction, nonlinearity and focusing. The first applications of shear acoustic waves in TDBS-based imaging have been recently reported. The theory of TDBS-based imaging suggests multiple perspectives for its further development. References: 1. V. E. Gusev and P. Ruello, Advances in applications of time-domain Brillouin scattering for nanoscale imaging, Appl. Phys. Rev. 5, 031101 (2018); https://doi.org/10.1063/1.5017241. 2. J. D. G. Greener, E. de Lima Savi, A. V. Akimov, S. Raetz, Z. Kudrynskyi, Z. D. Kovalyuk, N. Chigarev, A. Kent, A. Patanè, and V. Gusev, High frequency elastic coupling at the interface of van der Waals nanolayers imaged by picosecond ultrasonics, ACS Nano 13 (10) 11530-11537 (2019); https://doi.org/10.1021/acsnano.9b05052 3. Y. Wang, D. H. Hurley, Z. Hua, T. Pezeril, S. Raetz, V. E. Gusev, V. Tournat & M. Khafizov, Imaging grain microstructure in a model ceramic energy material with optically generated coherent acoustic phonons, NATURE COMMUNICATIONS 11, 1597 (2020) ; https://doi.org/10.1038/s41467-020-15360-3 _________________________________________________________________________________ LECTURE 4(I)Picosecond Acoustics: from lab to fabSpeaker: Arnaud Devos Keywords: picosecond acoustics,thickness control, thin-film, elasticity, adhesion, RFfilters Summary : The main goal of this lecture is to give an outlook of the numerous and various applications that the picosecond acoustic technique has met in the industrial world. The story started a few years after its invention by Prof. H. Maris. Indeed, Rudolph Technologies (now ONTO) rapidly realized that such a technique was the missing one in the industrial world for controlling the thickness of thin metal films. That was the beginning of the Metapulse® story, a full automatized tool dedicated to microelectronics applications and that can be found in any production company worthy of the name. More recently, picosecond acoustics and especially its variant based on laser-tuning, the so-called Colored Picosecond Acoustics or APiC, have been shown to be very useful for many other industrial applications in topics as different as space mirror, radio-frequency filtering, flat and smart glass, solar cells,… References: [1]. A. DEVOS, “Colored Ultrafast Acoustics: from fundamentals to applications”, Ultrasonics 56, pp. 90-97 (2015) DOI 10.1016/j.ultras.2014.02.009 _________________________________________________________________________________ LECTURE 5
(II)Time-domain Brillouin scattering: theoretical backgrounds and applications for nanoscale imaging and materials characterizationSpeaker: Vitali E. Gusev Keywords: photoacoustics; optoacoustics; laser ultrasound; time-domain Brillouin scattering; picosecond acoustic interferometry; imaging; microscopy; vibrations of nanolayers and nanostructures Summary: Time-domain Brillouin scattering (TDBS), also known as picosecond acoustic interferometry, is an experimental technique that uses ultrafast lasers for generation and detection of nanometer-scale coherent acoustic pulses with picosecond scale time duration. Detection involves interfering two weak probe light pulses: one scattered by the acoustic nanopulse propagating in transparent materials, and one reflected from various interfaces of the sample. Transient optical reflectivity recorded by a photodetector, as the acoustic nanopulse propagates, contains information on local acoustical, optical, and acousto-optical parameters of the material. TDBS imaging is based on Brillouin scattering and has potential to provide all information that researchers in materials science, physics, chemistry, biology etc., could get with classic frequency-domain Brillouin scattering. It can be viewed as a replacement for Brillouin microscopy in all investigations where nanoscale spatial resolution is required. TDBS has been already applied for imaging of nanoporous films, ion-implanted semiconductors/dielectrics, grain boundaries, metal-epoxy interfaces, vegetable and animal cells, texture in polycrystalline materials, temperature distributions in liquids, and for monitoring the transformation of nanosound caused by absorption, diffraction, nonlinearity and focusing. The first applications of shear acoustic waves in TDBS-based imaging have been recently reported. The theory of TDBS-based imaging suggests multiple perspectives for its further development. References: 1. V. E. Gusev and P. Ruello, Advances in applications of time-domain Brillouin scattering for nanoscale imaging, Appl. Phys. Rev. 5, 031101 (2018); https://doi.org/10.1063/1.5017241. 2. J. D. G. Greener, E. de Lima Savi, A. V. Akimov, S. Raetz, Z. Kudrynskyi, Z. D. Kovalyuk, N. Chigarev, A. Kent, A. Patanè, and V. Gusev, High frequency elastic coupling at the interface of van der Waals nanolayers imaged by picosecond ultrasonics, ACS Nano 13 (10) 11530-11537 (2019); https://doi.org/10.1021/acsnano.9b05052 3. Y. Wang, D. H. Hurley, Z. Hua, T. Pezeril, S. Raetz, V. E. Gusev, V. Tournat & M. Khafizov, Imaging grain microstructure in a model ceramic energy material with optically generated coherent acoustic phonons, NATURE COMMUNICATIONS 11, 1597 (2020) ; https://doi.org/10.1038/s41467-020-15360-3
_________________________________________________________________________________ LECTURE 6Low frequency Raman scattering to probe nano-objects
Speaker: Alain Mermet Keywords: Raman, Brillouin, nanoparticles, nanoplates Summary :Halfway between Brillouin scattering and conventional Raman spectroscopy, low frequency Raman scattering allows to probe nano-objects through localized acoustic modes (also called Lamb modes) [1]. Initially uncovered as an original technique to evaluate the size of nanoparticles, low frequency Raman scattering has proved over the past two decades, thanks to continuous spectroscopic improvements and increased control of nanoparticle synthesis methods, to be able to probe fine details of nanostructures with diverse morphologies. After discussing the specificity of low frequency Raman scattering with respect to Brillouin and conventional Raman spectroscopies, we will illustrate from recent examples how the low-frequency Raman probe allows to assess crystallinity in metallic nanocrystals [2], probe the elastic coupling in a nanoparticle dimer [2] and sense nanomass loads in semiconductor nanoplates [3].
References: [1] L. Saviot, A. Mermet & E. Duval, "Nanoparticles and Quantum Dots, Handbook of Nanophysics", edited by K. D. Sattler (CRC Press, 2010) Chap. 11, pp. 11.1-11.17 [2] H. Portales; N. Goubet, L. Saviot, S. Adichtchev, DB Murray, A. Mermet, E. Duval, MP Pileni, PNAS, 14874 (2008) [3] A. Girard, H. Gehan, A. Crut, A. Mermet, L. Saviot, J. Margueritat, Nanoletters 6, 3843 (2016) [3] A. Girard, L. Saviot, S. Pedetti, MD Tessier, J. Margueritat, H. Gehan, B. Mahler, B. Dubertret, A. Mermet, Nanoscale, 13251 (2016) _________________________________________________________________________________ LECTURE 7
Part I: Current understanding and unsolved problems in thermal transport at the nanoscaleSpeaker: David Cahill Keywords: Nanoscale thermal transport; time-domain thermoreflectance Summary : On length scales large compared to the mean-free-paths and equilibration lengths of the excitations that carrier heat, the diffusion equation is an accurate description of the relationship between temperature fields and heat fluxes. On small spatial and temporal scales, this simple description fails due to scattering of excitations by boundaries and the out-of-equilibrium distributions of heat carriers that are induced by heat flow across material interfaces. In this lecture, I will provide an overview of what is known and not known in the physics of thermal transport at the nanoscale with an emphasis on experimental studies of dielectric and metallic crystals and their interfaces at temperatures near ambient. I will also introduce the emerging area of thermally-driven generation and transport of spin in magnetic materials on ultrafast time-scales.
References: Cahill et al., Nanoscale thermal transport II, Applied Physics Reviews 1, 011305 (2014). Choi et al., Thermal spin-transfer torque driven by the spin-dependent Seebeck effect in metallic spin-valves, Nature Physics 11, 576-581 (2015). _________________________________________________________________________________ LECTURE 8Part II: Measurement of thermal transport coefficients at the nanoscaleSpeaker: David Cahill Keywords: Nanoscale thermal transport; time-domain thermoreflectance Summary : I will discuss the use of time-domain thermoreflectance (TDTR) for measurements of thermal transport properties of materials and material interfaces and compare the capabilities and limitations of TDTR to other methods that are widely used in studies of nanoscale thermal transport: the 3-omega method, transient thermal gratings, frequency domain thermoreflectance, and microfabricated test platforms. I will discuss the basic implementation of the TDTR method, the analysis of the data based on the diffusion equation and radiative boundary conditions at interfaces, and evaluation of uncertainties. I will then discuss extensions of TDTR to include lateral heat flow, two-channel modeling of non-equilibrium effects, spot size and frequency dependence of the apparent value of the transport coefficients and the use of the time-resolved magneto-optic Kerr effect as an alternative to thermoreflectance for sensing temperature changes at the surface of a sample. References: Cahill, Analysis of heat flow in layered structures for time-domain thermoreflectance, Review of Scientific Instruments 75, 5119-5122 (2004). Jiang et al., Tutorial: Time-domain thermoreflectance (TDTR) for thermal property characterization of bulk and thin film materials, Journal of Applied Physics 124, 161103 (2018).
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(II)Picosecond Acoustics: from lab to fabSpeaker: Arnaud Devos Keywords: picosecond acoustics,thickness control, thin-film, elasticity, adhesion, RFfilters Summary : The main goal of this lecture is to give an outlook of the numerous and various applications that the picosecond acoustic technique has met in the industrial world. The story started a few years after its invention by Prof. H. Maris. Indeed, Rudolph Technologies (now ONTO) rapidly realized that such a technique was the missing one in the industrial world for controlling the thickness of thin metal films. That was the beginning of the Metapulse® story, a full automatized tool dedicated to microelectronics applications and that can be found in any production company worthy of the name. More recently, picosecond acoustics and especially its variant based on laser-tuning, the so-called Colored Picosecond Acoustics or APiC, have been shown to be very useful for many other industrial applications in topics as different as space mirror, radio-frequency filtering, flat and smart glass, solar cells,… References: [1]. A. DEVOS, “Colored Ultrafast Acoustics: from fundamentals to applications”, Ultrasonics 56, pp. 90-97 (2015) DOI 10.1016/j.ultras.2014.02.009 _________________________________________________________________________________ LECTURE 10High-Brightness Ultrafast Transmission Electron Microscopy: Applications to Nano-optics and Nanomechanics
Speaker: Arnaud Arbouet Keywords: Ultrafast Transmission Electron Microscopy, nano-optics, electron energy gains, acoustic vibrations Summary (5 to 10 lines): Nanosized systems have optical properties that can differ significantly from their bulk counterpart due to the existence of optical resonances such as surface plasmons in metallic nanoparticles or Mie modes in high refractive index nanostructures. These excitations have extremely short lifetimes (fs-ns) and pattern the optical near-field on subwavelength scales. Ultrafast Transmission Electron Microscopes (UTEM) combining sub-picosecond temporal resolution and nanometer spatial resolution have emerged as unique tools for investigations at ultimate spatio-temporal resolution [1,2]. In this talk, I will report on the development of a high-brightness UTEM and discuss its potential in nano-optics and nanomechanics [3,4]. In particular, I will report on Electron Energy Gain Spectroscopy experiments performed in a UTEM that allow mapping the optical near-field at the nanometer scale and discuss the potential of electron diffraction and holography experiments performed with femtosecond electron pulses to explore the vibrational dynamics of nanoscale systems. References: [1] 4D Electron Microscopy, Imaging in Space and Time, 2009 Ahmed H Zewail and John M Thomas (Cambridge) [2] Ultrafast Transmission Electron Microscopy : fundamentals, instrumentation and applications [3] Development of a high brightness ultrafast Transmission Electron Microscope based on a laser-driven cold field emission source [4] High brightness ultrafast transmission electron microscope based on a laser-driven cold-field emission source: principle and applications
_________________________________________________________________________________ LECTURE 11An introduction to nanomechanicsSpeaker: Eva Weig Keywords: mechanical resonators, nanomechanical systems, flexural modes Summary (5 to 10 lines): Nano- or micromechanical resonators are freely suspended structures with discrete vibrational eigenmodes, such as, e.g., the flexural modes of a string or a membrane. These resonators are receiving an increasing amount of attention for a broad range of possible applications, ranging from practical sensing to fundamental challenges addressing the foundations of quantum mechanics. This lecture will review the basics of nanomechanical resonators, and present some fields of use, including the thriving field of cavity optomechanics. References: M. Poot & H. S. J. van der Zant, Mechanical systems in the quantum regime, Phys. Rep. 511, 273 (2012). M. Aspelmeyer, T. J. Kippenberg & F. Marquardt, Cavity optomechanics, Rev. Mod. Phys. 86, 1391 (2014). _________________________________________________________________________________ LECTURE 12
Biosensors based on optonanomechanical systemsSpeaker: Monserrat Calleja Keywords: biosensors, nanomechanics, optomechanics Summary : We will be discussing the application of optomechanics to biology and biomedicine, as well as how strategies inspired by these phenomena can be applied to microscale devices for cancer cell characterization, for the detection of attogram per mililliter concentrations of protein biomarkers in the exploration of the deep plasma proteome and for the identification of pathogens through their intrinsic mechanical properties. References: [1] Biosensors based on nanomechanical systems, J Tamayo at al, Chemical Society Reviews 42 (3), 1287 (2013) [2]Mass and stiffness spectrometry of nanoparticles and whole intact bacteria by multimode nanomechanical resonators O Malvar, JJ Ruz, PM Kosaka, CM Domínguez, E Gil-Santos, M Calleja, J Tamayo, Nature communications 7, 13452 (2016) [3]Silicon nanowires: where mechanics and optics meet at the nanoscale, D Ramos, E Gil-Santos, O Malvar, JM Llorens, V Pini, A San Paulo, M Calleja, J Tamayo, Scientific reports 3, 3445 (2013) [4] Optomechanics with silicon nanowires by harnessing confined electromagnetic modes, D Ramos, E Gil-Santos, V Pini, JM Llorens, M Fernández-Regúlez, A San Paulo, M Calleja, J Tamayo, Nano letters 12 (2), 932-937 (2012) [5]Mechano-optical analysis of single cells with transparent microcapillary resonators, A Martín-Pérez, D Ramos, E Gil-Santos, S García-López, ML Yubero, PM Kosaka, A San Paulo, J Tamayo, M Calleja, ACS sensors 4 (12), 3325-3332, 2019 [6]Detection of cancer biomarkers in serum using a hybrid mechanical and optoplasmonic nanosensor, PM Kosaka, V Pini, JJ Ruz, RA Da Silva, MU González, D Ramos, M Calleja, J Tamayo, Nature nanotechnology 9 (12), 1047 (2014) [7]Optomechanical devices for deep plasma cancer proteomics, PM Kosaka, M Calleja, J Tamayo, Seminars in cancer biology 52, 26-38 (2018) [8] Gil-Santos, E., Ruz, J.J., Malvar, O. et al. Optomechanical detection of vibration modes of a single bacterium. Nat. Nanotechnol. 15, 469–474 (2020). https://doi.org/10.1038/s41565-020-0672-y [9] Juan Molina, Daniel Ramos, Eduardo Gil-Santos, Javier E. Escobar, José J. Ruz, Javier Tamayo, Álvaro San Paulo, and Montserrat Calleja. Optical Transduction for Vertical Nanowire Resonators. Nano Letters 2020 20 (4), 2359-2369. DOI: 10.1021/acs.nanolett.9b04909 _________________________________________________________________________________ LECTURE 13Stimulated Brillouin scattering microscopy for mechanical imaging of cells and organismsSpeaker: Alberto Bilenca Keywords: Stimulated Brillouin scattering, microscopy, biomechanics Summary: The mechanical properties of biological systems, such as cells and organisms, play a major role in their function and development. One established technique for assessing biomechanics is atomic-force microscopy, but it requires contact with the sample. Recently, Brillouin microscopy has been developed for biomechanical imaging with no sample contact or external mechanical stimulus. Whereas most of the development efforts in Brillouin microscopy have used spontaneous Brillouin scattering as the contrast mechanism, I will introduce here a new approach for high sensitivity and specificity, noncontact, biomechanical-contrast imaging based on stimulated Brillouin scattering (SBS). The physical working principles of the method and its use in biological settings will be described and discussed in detail. References: Itay Remer, Roni Shaashoua, Netta Shemesh, Anat Ben-Zvi, Alberto Bilenca, “High-sensitivity and high-specificity biomechanical imaging by stimulated Brillouin scattering microscopy,” Nat Methods 17, 913-916 (2020). Itay Remer, Lear Cohen, Alberto Bilenca, “High-speed continuous-wave stimulated Brillouin scattering spectrometer for material analysis,” J Vis Exp 127, 55527 (2017). _________________________________________________________________________________ LECTURE 14Picosecond Acoustics: a Laser Pump-Probe Technique for the Determination of Thermo-Elastic Properties of Solids and Liquids at High Pressure and High TemperatureSpeaker: Silvia Boccato Keywords: picosecond acoustics, elastic constants, sound velocity, high pressure, high temperature Summary :Picosecond acoustics is a time-resolved optical pump-probe technique that allows studying the propagation of acoustic echoes in a large variety of samples at different pressure and temperature conditions. With this technique we can access melting curves, the complete set of elastic moduli for single crystals and longitudinal velocities for polycrystalline samples. I will illustrate the importance of these experiments for Earth and planetary science, providing examples of studies with a direct interest in these fields, including measurements on iron and iron alloys, metallic liquids, hydrogen and deuterium. _________________________________________________________________________________ LECTURE 15
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_________________________________________________________________________________ LECTURE 17Measurements of sound absorption and phonon lifetimes with picosecond ultrasonics techniqueSpeaker: Bernard Perrin (Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP, F-75005 Paris, France.) Keywords:Picosecond ultrasonics, acoustic attenuation, phonon mean free path, phonon lifetime Summary Attenuation of acoustic waves can be a limiting factor in many areas such as high frequency acoustic imaging, surface wave devices or very high quality factor resonators. Picosecond ultrasonics technique offers a very good opportunity to perform attenuation measurements over a wide frequency and temperature range. This lecture will start with a brief discussion of the different regimes of sound absorption which occur according to the frequency and temperature domains. The second part will be devoted to the different configurations which can be used to measure this parameter in pump probe experiments. The many artefacts that can interfere with the measurements will be discussed in detail. At the end, a review of experimental results, obtained on different systems (thin films bulk materials, membranes, resonators) and different materials (crystals, amorphous systems, quasi-crystals), will be given. _________________________________________________________________________________ LECTURE 18
Vibrational and Cooling Dynamics of Metal Nanoparticles:Optical Investigations and ModelingSpeaker: Aurelien Crut Keywords: metal nanoparticles, time-resolved spectroscopy, vibration modes, single-particle spectroscopy, interfacial phonon transfer, plasmonics Summary: Nano-objects exhibit discrete vibrational modes, which can be monitored in the time domain using ultrafast optical pump-probe spectroscopy. This enables both the design of artificial nanoresonators with frequencies reaching the THz domain and fundamental investigations of the laws governing acoustics at the nanoscale. In particular, measuring the frequencies of the vibrational modes of small nanoparticles (with sizes down to few atoms) allows one to test the accuracy of their description using continuum elasticity theory. Their damping is usually dominated by energy transfer from the nano-objects to their environment (a mechanism also ruling nano-object cooling), its investigation ideally requiring measurements at the single-particle level to avoid the inhomogeneous broadening effects affecting ensemble experiments. In this talk, after discussing the vibrational and cooling dynamics of nano-objects, I will present their investigation by time-resolved pump-probe spectroscopy of ensembles of nano-objects and single ones, as well as their modeling using analytical and numerical approaches. References: 1) A. Crut, P. Maioli, N. Del Fatti and F. Vallée Optical absorption and scattering spectroscopies of single nano-objects Chem. Soc. Rev. 43, 3921 (2014). 2) A. Crut, P. Maioli, N. Del Fatti and F. Vallée Acoustic vibrations of metal nano-objects: time-domain investigations Phys. Rep. 549, 1 (2015). _________________________________________________________________________________ LECTURE 19 & 20
Raman ImagingSpeaker: Hervé Rigneault Keywords: Vibrational imaging, Raman imaging, Coherent Raman Imaging Summary : I will review and present the basics and technical implementations of Raman imaging and coherent Raman imaging. I will exemplify the methods in compressive spontaneous Raman for fast chemical spectroscopy and imaging. To reach higher frame rate, I will present the latest development in coherent Raman both in the high and low frequency ranges. Finally I will present our effort to push Raman imaging in endoscopes. References: TUTORIALS: H. Rigneault, and P. Berto, "Tutorial: Coherent Raman light matter interaction processes," APL Photonics 3, 091101 (2018). https://doi.org/10.1063/1.5030335 X. Audier, S. Heuke, P. Volz, I. Rimke, and H. Rigneault, "Noise in stimulated Raman scattering measurement: From basics to practice," APL Photonics 5, 011101 (2020).https://doi.org/10.1063/1.5129212 X. Audier, N. Forget, and H. Rigneault, "High-speed chemical imaging of dynamic and histological samples with stimulated Raman micro-spectroscopy," Optics Express 28, 15505-15514 (2020). https://doi.org/10.1364/OE.390850_________________________________________________________________________________ LECTURE 21Sensing with plasmons and Raman scatteringSpeaker: Nathalie Lidgi-Guigui Keywords: Plasmons, Raman scattering, Surface Enhanced Raman Scattering, biosensing, sensing Summary : During this course I will start by briefly presenting the physics of surface and localised plasmons. I will then present how these localized surface plasmons can be used to enhance Raman scattering. In a second part I will discuss the notion of molecular detection based on plasmons and Raman spectroscopy. I will consider in particular the detection of biomolecules in complex media such as blood or urine. For this I will introduce very basics notions of molecular biology and surface chemistry. _________________________________________________________________________________ LECTURE 22Brillouin and Raman spectroscopy to investigate metastable waterSpeaker: Frédéric Caupin Keywords: Brillouin spectroscopy, Raman spectroscopy, water, metastability, equation of state Summary : As any liquid, water can be prepared in a metastable liquid state: supercooled below the ice-liquid equilibrium temperature, or stretched below the liquid-vapor equilibrium pressure, down to negative pressure. The properties of water in these states is key to understanding the origin of its anomalies. However, measuring these properties is challenging because external perturbations can easily nucleate the more stable phase. Non-intrusive optical measurements are thus a tool of choice. This lecture will describe two examples: accurate size measurement of supercooled evaporating droplets with Raman spectroscopy [1], and equation of state at negative pressure with Brillouin spectroscopy [2,3,4]. References: [1] C. Goy et al. Shrinking of rapidly evaporating water microdroplets reveals their extreme supercooling. Phys. Rev. Lett., 2018, 120, 015501. [2] G. Pallares et al. Anomalies in bulk supercooled water at negative pressure. Proc. Natl. Acad. Sci. USA, 2014, 111, 7936-7941. [3] G. Pallares et al. Equation of state for water and its line of density maxima down to [4] V. Holten et al. Compressibility anomalies in stretched water and their interplay with density anomalies. J. Phys. Chem. Lett., 2017, 8, 5519–5522. _________________________________________________________________________________ LECTURE 23Picosecond ultrasonic microscopy to image the cell mechanics and probe its nanostructure
Speaker: Bertrand Audouin Summary: This presentation will review the current state of the art solutions offered by the picosecond ultrasonic technique to achieve single cell microscopy. Among them is the time domain Brillouin spectroscopy that allows probing ultrasound propagation along the cell depth. When coupled with convenient scanning devices and fast acquisition systems the technique allows for imaging several mechanical properties with an in-plane resolution equal to that provided by standard optics. The current and foreseen applications in biology and medicine will be discussed.
References: C. Rossignol et al. Appl. Phys. Lett. 93,123901, 2008 T. Dehoux et al., Scient. Rep. 5, 8650, 2015 S. Danworaphong et al. Appl. Phys. Let. 106, 163701, 2015 F. Perez-Cota et al. Scient. Rep. 6, 39326, 2016 A. Viel et al. Appl. Phys. Let. 115, 213701, 2019 L. Liu et al. J. of Biophot. 201900045, 2019 L. Liu et al. Scient. Rep. 9, 6409, 2019 _________________________________________________________________________________ LECTURE 24Vibrational spectroscopy in the acoustic band:
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