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Showing 1 to 20 of 31 for “"Transient Grating"”.
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Ultrahigh frequency characterization of complex materials using transient grating techniques
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemistry, 2000
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Transient Grating Spectroscopy: Compact System Geometry Developments and Improved Software
Transient grating spectroscopy (TGS) is a rapid, non-destructive technique for measuring the thermal, elastic, and acoustic properties of the top several microns of a reflective surface. It has uses across many areas of materials research. Current TGS systems require complex optics tables taking up …
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Evaluating Fluoride Molten Salt Thermophysical Properties with Transient Grating Spectroscopy
… in non-fluoride salts when measured using Transient Grating Spectroscopy (TGS). This work has shown that convection and radiation are insignificant for most TGS regimes. Therefore, it was hypothesized that TGS measurements of fluorides could finally resolve the discrepancies between theory …
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Breaking the bottleneck in radiation materials science with transient grating spectroscopy
… reactor environment can be accurately predicted. Transient grating spectroscopy (TGS), long used in the materials science field to characterize the properties of thin films, is adapted for use as a method of characterizing radiation-damaged samples. TGS has the ability to simultaneously measure …
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Optical transient grating measurements of micro/nanoscale thermal transport and mechanical properties
The laser-based transient grating technique was used to study phonon mediated thermal transport in bulk and nanostructured semiconductors and surface wave propagation in a monolayer of micron sized spheres. In the transient grating technique two picosecond pulses are crossed to generate a spatially …
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A Detailed Treatment of the Measurement of Transport Coefficients in Transient Grating Experiments
… the measurement of transport coefficients in transient grating experiments and is organized into 3 parts. Part 1 provides a brief review of the thermodynamic-phenomenological theory relevant for a correct description of the Soret effect. It comprises the formulation of the first law in open …
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In-situ investigation of the oxidation kinetics of Fe-12Cr-2Si using time-resolved transient grating spectroscopy
… known as dual heterodyne phase collection transient grating spectroscopy is developed for this purpose. This method adapts a traditional spectroscopic technique sensitive to thermal and mechanical properties for real-time use. A formalism is also developed to quantify both elastic and …
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Ultrafast linear and non-linear spectroscopy : from biological light-receptors to artificial light-harvesting systems
… in this work utilize femtosecond time-resolved transient absorption and transient grating as well as picosecond time-resolved fluorescence spectroscopy to investigate the photophysics and photochemistry of biological photoreceptors and address the light-induced excited-state processes in a …
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TIME RESOLVED PROBING OF MAGNETO-ELASTIC EXCITATIONS IN MAGNETIC MATERIALS
… Trieste), I developed a setup to perform optical Transient-Grating spectroscopy, and correlative time-resolved optical spectroscopies (time-resolved reflectivity and polarimetry). Via sub-picosecond optical pulses, acoustic and magnetic transients are impulsively generated: their intertwined …
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Photochemical Applications to the Study of Complexity Phospholipid Bilayer Environments
… properties of the bilayer. In addition, transient grating spectroscopy was used to study thermal energy transfer in phospholipid bilayers on a picosecond time scale.Femtosecond transient absorption spectroscopy was used to study the photo-induced spiropyran ring-opening and isomerization …
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Exploring the Effect of Irradiation Time on the Damping of Surface Acoustic Waves
… used to examine material properties, including transient grating spectroscopy (TGS). These properties were used to probe several scales of structure, and TGS has been applied in this way to solve several challenges. This thesis explores the details of the TGS signal itself, and how the property …
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Investigation of carrier dynamics in InN, InGaN, and GaAsBi by optical pump-probe techniques /
… GaAsBi heterostructures by using light-induced transient gratings and differential transmission techniques. The experimental studies in a wide range of excess carrier densities and temperatures revealed that trap-assisted Auger recombination is the dominant recombination mechanism in MBE-grown …
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DEGENERATE SECOND ORDER NONLINEAR OPTICAL SPECTROSCOPY OF CHIRAL WEYL SEMIMETALS
… second harmonic generation (RA-SHG) and transient grating. In our work on SHG, we describe a fast-reflective optic-based rotational anisotropy nonlinear harmonic generation spectrometer built upon synchronization of stepper motors and a voice-coil fast turning motor with data recorded by …
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Design and fabrication of granular materials for surface acoustic waves
… spheres adhered to the substrate. Laser-induced transient grating technique is used to generate and detect surface acoustic waves in microsphere array samples. We demonstrate, both experimentally and by theoretical analysis, that the Rayleigh wave in the substrate interacts with the contact …
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Phonon hydrodynamic transport at elevated temperature
… be observed up to 90 K. Using a sub-picosecond transient grating technique, we directly observed second sound in graphite at record-high temperatures of 200 K. With the enlarged grating-period window, we firstly reported the dispersion of thermal wave, whose velocity increases with decreasing …
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Phonon hydrodynamic transport at elevated temperature
… be observed up to 90 K. Using a sub-picosecond transient grating technique, we directly observed second sound in graphite at record-high temperatures of 200 K. With the enlarged grating-period window, we firstly reported the dispersion of thermal wave, whose velocity increases with decreasing …
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Optical characterization of thermal transport from the nanoscale to the macroscale
… fluid is studied systematically. An optical transient grating technique is used to explore the bulk thermal and viscous properties of nanofluids.
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TIME-DOMAIN INVESTIGATION OF ACOUSTICALLY AND THERMALLY DRIVEN MAGNONS
… Ni thin films was investigated using the Transient Grating (TG) technique. The focus was on examining how the acoustic waves generated in the substrate influence and drive the magnetization dynamics of the Ni thin films via magnetoelastic coupling. In a second experiment, the TG approach …
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Picosecond Dynamics of Free-Carrier Populations, Space-Charge Fields, and Photorefractive Nonlinearities in Zincblende Semiconductors
… electronic applications. We use a novel transient-grating experimental method that allows picosecond temporal resolution and high sensitivity. Our results provide a clear and detailed picture of the picosecond photorefractive response of both materials, showing nonlinearities due to …
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Multidimensional Spectroscopy With Femtosecond Pulses
… The other method discussed here is a 2nd order transient grating spectroscopy called MUPPETS, a method which enables distinction between homogeneous and heterogeneous sources of nonexponential rates. The specifics of this set up will be detailed, as well as the results of a run performed on …
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