New approaches for high spatial and temporal resolution nanothermometry : development of hot wire nano heater devices and investigation of thermosensitive materials with fluorescent and spin crossover properties / Olena Kraieva  

Public ISBD Titre : New approaches for high spatial and temporal resolution nanothermometry : development of hot wire nano heater devices and investigation of thermosensitive materials with fluorescent and spin crossover properties Type de document : texte imprimé Auteurs : Olena Kraieva, Auteur ; Gabor Molnar, Directeur de thèse ; Azzedine Bousseksou, Directeur de thèse Langues : Anglais (eng) Tags : NANO  THERMOMETRY  SPIN CROSSOVER  THERMAL IMAGING  LITHOGRAPHY  NANO-HEATER DEVICE  LUMINOPHORE  JOULE EFFECT Résumé : "The overall objective of this PhD thesis was to develop novel micro- and nano-thermometry methods providing high spatial and temporal resolution thermal imaging. To achieve this goal we have focused on two tasks: First, we developed a nano-heater device that can be easily employed for the thermo-physical characterization of materials at the nanoscale. In a second time, using this platform we investigated thermo-sensitive materials, including different luminophores and spin crossover complexes as well as their mixtures. The nano-heater device, based on Joule-heated metallic nanowires, was fabricated by standard electron beam lithography. Due to their small thermal mass, nanowire based devices are particularly interesting in terms of response times and also in terms of confinement of the induced temperature changes. The thermal characterization of these heating elements was carried out using electrical and optical methods as well as finite element simulations. We have shown experimentally that our heaters can provide fast (< µs) and spatially well localized (< µm) T-jump perturbations (1 K < DeltaT < 80 K) driven by an electrical current pulse. Finite element simulations reproduced these experimental results with good accuracy and proved to be a powerful tool of prediction for the device design. Fluorescent materials, including organic dyes (Rhodamine B), inorganic nanoparticles (PbF2:Er3+/Yb3+, CdSe) and hybrid organic/inorganic nanoparticles ([Fe(Htrz)2(trz)]BF4@SiO2-pyrene), were then investigated for their thermometry performance. Overall, they were found useful for thermal imaging, but stability problems make quantitative measurements challenging with these materials. On the other hand, we have succeeded in synthesizing nanoparticle films of the (undoped) [Fe(Htrz)2(trz)]BF4 spin crossover complex, which allowed us to infer temperature changes through more robust optical reflectivity measurements. The thermal hysteresis loop in this material provides a long-term thermal memory effect which we used successfully to image very fast (˜µs) transient temperature changes with high spatial resolution (sub-µm) - even when the heat is dissipated. This original method provides an unprecedented combination of spatio-temporal sensitivity within the field of nanothermometry with promising potential applications." Document : thèse de Doctorat Etablissement_delivrance : Université Toulouse 3 Date_soutenance : 26/10/2015 Ecole_doctorale : Sciences de la matière (SdM) Domaine : Nano-physique, nano-composants, nano-mesures En ligne : http://thesesups.ups-tlse.fr/3044/ New approaches for high spatial and temporal resolution nanothermometry : development of hot wire nano heater devices and investigation of thermosensitive materials with fluorescent and spin crossover properties [texte imprimé] / Olena Kraieva, Auteur ; Gabor Molnar, Directeur de thèse ; Azzedine Bousseksou, Directeur de thèse . - [s.d.]. Langues : Anglais (eng) Tags : NANO  THERMOMETRY  SPIN CROSSOVER  THERMAL IMAGING  LITHOGRAPHY  NANO-HEATER DEVICE  LUMINOPHORE  JOULE EFFECT Résumé : "The overall objective of this PhD thesis was to develop novel micro- and nano-thermometry methods providing high spatial and temporal resolution thermal imaging. To achieve this goal we have focused on two tasks: First, we developed a nano-heater device that can be easily employed for the thermo-physical characterization of materials at the nanoscale. In a second time, using this platform we investigated thermo-sensitive materials, including different luminophores and spin crossover complexes as well as their mixtures. The nano-heater device, based on Joule-heated metallic nanowires, was fabricated by standard electron beam lithography. Due to their small thermal mass, nanowire based devices are particularly interesting in terms of response times and also in terms of confinement of the induced temperature changes. The thermal characterization of these heating elements was carried out using electrical and optical methods as well as finite element simulations. We have shown experimentally that our heaters can provide fast (< µs) and spatially well localized (< µm) T-jump perturbations (1 K < DeltaT < 80 K) driven by an electrical current pulse. Finite element simulations reproduced these experimental results with good accuracy and proved to be a powerful tool of prediction for the device design. Fluorescent materials, including organic dyes (Rhodamine B), inorganic nanoparticles (PbF2:Er3+/Yb3+, CdSe) and hybrid organic/inorganic nanoparticles ([Fe(Htrz)2(trz)]BF4@SiO2-pyrene), were then investigated for their thermometry performance. Overall, they were found useful for thermal imaging, but stability problems make quantitative measurements challenging with these materials. On the other hand, we have succeeded in synthesizing nanoparticle films of the (undoped) [Fe(Htrz)2(trz)]BF4 spin crossover complex, which allowed us to infer temperature changes through more robust optical reflectivity measurements. The thermal hysteresis loop in this material provides a long-term thermal memory effect which we used successfully to image very fast (˜µs) transient temperature changes with high spatial resolution (sub-µm) - even when the heat is dissipated. This original method provides an unprecedented combination of spatio-temporal sensitivity within the field of nanothermometry with promising potential applications." Document : thèse de Doctorat Etablissement_delivrance : Université Toulouse 3 Date_soutenance : 26/10/2015 Ecole_doctorale : Sciences de la matière (SdM) Domaine : Nano-physique, nano-composants, nano-mesures En ligne : http://thesesups.ups-tlse.fr/3044/

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