Microscopic electric fields govern the majority of elementary excitations in condensed matter and drive electronics at frequencies approaching the Terahertz(THz)regime.However,only few imaging schemes are able to reso...Microscopic electric fields govern the majority of elementary excitations in condensed matter and drive electronics at frequencies approaching the Terahertz(THz)regime.However,only few imaging schemes are able to resolve sub-wavelength fields in the THz range,such as scanning-probe techniques,electro-optic sampling,and ultrafast electron microscopy.Still,intrinsic constraints on sample geometry,acquisition speed and field strength limit their applicability.Here,we harness the quantum-confined Stark-effect to encode ultrafast electric near-fields into colloidal quantum dot luminescence.Our approach,termed Quantum-probe Field Microscopy(QFIM),combines far-field imaging of visible photons with phase-resolved sampling of electric waveforms.By capturing ultrafast movies,we spatio-temporally resolve a Terahertz resonance inside a bowtie antenna and unveil the propagation of a Terahertz waveguide excitation deeply in the sub-wavelength regime.The demonstrated QFIM approach is compatible with strong-field excitation and sub-micrometer resolution—introducing a direct route towards ultrafast field imaging of complex nanodevices inoperando.展开更多
Herein, we fabricate hollow silica nanoparticles with exceptionally narrow size distributions that inherently possess two distinct length scales-tens of nanometers with regards to the shell thickness, and hundreds of ...Herein, we fabricate hollow silica nanoparticles with exceptionally narrow size distributions that inherently possess two distinct length scales-tens of nanometers with regards to the shell thickness, and hundreds of nanometers in regards to the total diameter. We characterize these structures using dynamic and static light scattering （DLS and SLS）, small angle X-ray scattering （SAXS）, and transmission electron microscopy （TEM）, and we demonstrate quantitative agreement among all methods. The ratio between the radius of gyration （SLS） and hydrodynamic radius （DLS） in these particles equals almost unity, corresponding to ideal capsule behavior. We are able to resolve up to 20 diffraction orders of the hollow sphere form factor in SAXS, indicating a narrow size distribution. Data from light and X-ray scattering can be combined to a master curve covering a q-range of four orders of magnitude assessing all hierarchical length scales of the form factor. The measured SLS intensity profiles noticeably change when the scattering contrast between the interior and exterior is altered, whereas the SAXS intensity profiles do not show any significant change. Tight control of the aforementioned length scales in one simple and robust colloidal building block renders these particles suitable as future calibration standards.展开更多
基金the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)via project 403711541T.L.acknowledges funding from the European Research Council(ERC)under the European Union’s Horizon 2020 research program(grant agreement no.714968)N.K.and P.M.thank the ARC for support through grant CE170100026.
文摘Microscopic electric fields govern the majority of elementary excitations in condensed matter and drive electronics at frequencies approaching the Terahertz(THz)regime.However,only few imaging schemes are able to resolve sub-wavelength fields in the THz range,such as scanning-probe techniques,electro-optic sampling,and ultrafast electron microscopy.Still,intrinsic constraints on sample geometry,acquisition speed and field strength limit their applicability.Here,we harness the quantum-confined Stark-effect to encode ultrafast electric near-fields into colloidal quantum dot luminescence.Our approach,termed Quantum-probe Field Microscopy(QFIM),combines far-field imaging of visible photons with phase-resolved sampling of electric waveforms.By capturing ultrafast movies,we spatio-temporally resolve a Terahertz resonance inside a bowtie antenna and unveil the propagation of a Terahertz waveguide excitation deeply in the sub-wavelength regime.The demonstrated QFIM approach is compatible with strong-field excitation and sub-micrometer resolution—introducing a direct route towards ultrafast field imaging of complex nanodevices inoperando.
文摘Herein, we fabricate hollow silica nanoparticles with exceptionally narrow size distributions that inherently possess two distinct length scales-tens of nanometers with regards to the shell thickness, and hundreds of nanometers in regards to the total diameter. We characterize these structures using dynamic and static light scattering （DLS and SLS）, small angle X-ray scattering （SAXS）, and transmission electron microscopy （TEM）, and we demonstrate quantitative agreement among all methods. The ratio between the radius of gyration （SLS） and hydrodynamic radius （DLS） in these particles equals almost unity, corresponding to ideal capsule behavior. We are able to resolve up to 20 diffraction orders of the hollow sphere form factor in SAXS, indicating a narrow size distribution. Data from light and X-ray scattering can be combined to a master curve covering a q-range of four orders of magnitude assessing all hierarchical length scales of the form factor. The measured SLS intensity profiles noticeably change when the scattering contrast between the interior and exterior is altered, whereas the SAXS intensity profiles do not show any significant change. Tight control of the aforementioned length scales in one simple and robust colloidal building block renders these particles suitable as future calibration standards.
