scholarly journals Peak force visible microscopy

Soft Matter ◽  
2020 ◽  
Vol 16 (36) ◽  
pp. 8372-8379
Author(s):  
Haomin Wang ◽  
Le Wang ◽  
Yuequn Shang ◽  
Sajedehalsadat Yazdanparast Tafti ◽  
Wenpeng Cao ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Spatial Resolution ◽  
Peak Force ◽  
Visible Range ◽  
Excellent Spatial Resolution ◽  
New Type ◽  
Photothermal Microscopy

We developed a new type of visible-range photothermal microscopy for measurement of optical absorption with excellent spatial resolution.

Automatic analysis of Kikuchi diffraction patterns

1994 ◽  
Vol 52 ◽  
pp. 900-901
Author(s):  
H. Weiland ◽  
D. P. Field
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Spatial Resolution ◽  
Relevant Information ◽  
Crystalline Materials ◽  
Large Size ◽  
Transmission Electron ◽  
New Type ◽  
Diffraction Patterns ◽  
Orientation Determination

Recent advances in the automatic indexing of backscatter Kikuchi diffraction patterns on the scanning electron microscope (SEM) has resulted in the development of a new type of microscopy. The ability to obtain statistically relevant information on the spatial distribution of crystallite orientations is giving rise to new insight into polycrystalline microstructures and their relation to materials properties. A limitation of the technique in the SEM is that the spatial resolution of the measurement is restricted by the relatively large size of the electron beam in relation to various microstructural features. Typically the spatial resolution in the SEM is limited to about half a micron or greater. Heavily worked structures exhibit microstructural features much finer than this and require resolution on the order of nanometers for accurate characterization. Transmission electron microscope (TEM) techniques offer sufficient resolution to investigate heavily worked crystalline materials.Crystal lattice orientation determination from Kikuchi diffraction patterns in the TEM (Figure 1) requires knowledge of the relative positions of at least three non-parallel Kikuchi line pairs in relation to the crystallite and the electron beam.

Liquid-Phase Peak Force Infrared Microscopy

2020 ◽  
Author(s):  
Haomin Wang ◽  
Joseph M. González-Fialkowski ◽  
Wenqian Li ◽  
Yan Yu ◽  
Xiaoji Xu
Keyword(s):  
Liquid Phase ◽  
Spatial Resolution ◽  
Shear Force ◽  
Polymer Surface ◽  
Surface Damage ◽  
Peak Force ◽  
Infrared Microscopy ◽  
Contact Mode ◽  
Force Microscopy ◽  
Hydrogen Deuterium

Atomic force microscopy-infrared microscopy (AFM-IR) provides a route to bypass Abbe’s diffraction limit through photothermal detections of infrared absorption. With the combination of total internal reflection, AFM-IR can operate in the aqueous phase. However, AFM-IR in contact mode suffers from surface damage from the lateral shear force between the tip and sample, and can only achieve 20~25-nm spatial resolution. Here, we develop the liquid-phase peak force infrared (LiPFIR) microscopy that avoids the detrimental shear force and delivers an 8-nm spatial resolution. The non-destructiveness of the LiPFIR microscopy enables <i>in situ</i> chemical measurement of heterogeneous materials and investigations on a range of chemical and physical transformations, including polymer surface reorganization, hydrogen-deuterium isotope exchange, and ethanol-induced denaturation of proteins. We also perform LiPFIR imaging of the budding site of yeast cell wall in the fluid as a demonstration of biological applications. LiPFIR unleashes the potential of in liquid AFM-IR for chemical nanoscopy.

scholarly journals Comparative Study on Electronic Structure and Optical Properties of α-Fe2O3, Ag/α-Fe2O3 and S/α-Fe2O3

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 424
Author(s):  
Cuihua Zhao ◽  
Baishi Li ◽  
Xi Zhou ◽  
Jianhua Chen ◽  
Hongqun Tang
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Electronic Structures ◽  
Density Functional ◽  
Peak Strength ◽  
Visible Range ◽  
High Symmetry ◽  
Functional Theory ◽  
Optical Absorption Peak ◽  
Calculation Results

The electronic structures and optical properties of pure, Ag-doped and S-doped α-Fe2O3 were studied using density functional theory (DFT). The calculation results show that the structure of α-Fe2O3 crystal changes after Ag and S doping, which leads to the different points of the high symmetry of Ag-doped and S-doped α-Fe2O3 with that of pure α-Fe2O3 in the energy band, as well as different Brillouin paths. In addition, the band gap of α-Fe2O3 becomes smaller after Ag and S doping, and the optical absorption peak shifts slightly toward the short wavelength, with the increased peak strength of S/α-Fe2O3 and the decreased peak strength of Ag/α-Fe2O3. However, the optical absorption in the visible range is enhanced after Ag and S doping compared with that of pure α-Fe2O3 when the wavelength is greater than 380 nm, and the optical absorption of S-doped α-Fe2O3 is stronger than that of Ag-doped α-Fe2O3.

Growth and Light Properties of Fluorescent SiC for White LEDs

2012 ◽  
Vol 717-720 ◽  
pp. 87-92
Author(s):  
Mikael Syväjärvi ◽  
Rositza Yakimova ◽  
Motoaki Iwaya ◽  
Tetsuya Takeuchi ◽  
Isamu Akasaki ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
White Light ◽  
Energy Savings ◽  
Red Light ◽  
Visible Range ◽  
White Led ◽  
Light Emitting ◽  
Blue Led ◽  
White Leds ◽  
New Type

The LED technology started to developed many years ago with red light emitting diodes. To achieve the blue LED, novel growth technologies and process steps were explored, and made it possible to demonstrate efficient blue LED performance from nitrides. The efficiency was further developed and blue LEDs were commercially introduced in the 1990’s. The white LED became possible by the use of the blue LED and a phosphor that converts a part of the blue light to other colors in the visible range to combine into white light. However, even today there are limitations in the phosphor-based white LED technology, in particular for general lighting, and new solutions should be explored to speed the pace when white LEDs will be able to make substantial energy savings. In this paper we overview gallium nitride materials evolution and growth concepts for LEDs. We describe the fluorescent silicon carbide material prepared by a novel growth technology for a new type of white LED in general lighting with pure white light. This paper introduces an interesting research in fundamental growth and optical properties of light emitting silicon carbide.

scholarly journals Recent progress in the development of near-infrared organic photothermal and photodynamic nanotherapeutics

2018 ◽  
Vol 6 (4) ◽  
pp. 746-765 ◽  
Author(s):  
Houjuan Zhu ◽  
Penghui Cheng ◽  
Peng Chen ◽  
Kanyi Pu
Keyword(s):  
Photodynamic Therapy ◽  
Side Effects ◽  
Spatial Resolution ◽  
Photothermal Therapy ◽  
Normal Tissue ◽  
Recent Progress ◽  
Near Infrared ◽  
Tumor Ablation ◽  
Ablation Efficiency ◽  
Excellent Spatial Resolution

Phototherapies including photothermal therapy (PTT) and photodynamic therapy (PDT) have gained considerable attention due to their high tumor ablation efficiency, excellent spatial resolution and minimal side effects on normal tissue.

scholarly journals Ternary nitride semiconductors in the rocksalt crystal structure

2019 ◽  
Vol 116 (30) ◽  
pp. 14829-14834 ◽  
Author(s):  
Sage R. Bauers ◽  
Aaron Holder ◽  
Wenhao Sun ◽  
Celeste L. Melamed ◽  
Rachel Woods-Robinson ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Crystal Structures ◽  
Main Group ◽  
Dielectric Constants ◽  
Visible Range ◽  
Superconducting Transition ◽  
Transition Metal Nitrides ◽  
Nitride Semiconductors ◽  
General Chemical ◽  
Ternary Nitride

Inorganic nitrides with wurtzite crystal structures are well-known semiconductors used in optical and electronic devices. In contrast, rocksalt-structured nitrides are known for their superconducting and refractory properties. Breaking this dichotomy, here we report ternary nitride semiconductors with rocksalt crystal structures, remarkable electronic properties, and the general chemical formula MgxTM1−xN (TM = Ti, Zr, Hf, Nb). Our experiments show that these materials form over a broad metal composition range, and that Mg-rich compositions are nondegenerate semiconductors with visible-range optical absorption onsets (1.8 to 2.1 eV) and up to 100 cm2 V−1⋅s−1 electron mobility for MgZrN2 grown on MgO substrates. Complementary ab initio calculations reveal that these materials have disorder-tunable optical absorption, large dielectric constants, and electronic bandgaps that are relatively insensitive to disorder. These ternary MgxTM1−xN semiconductors are also structurally compatible both with binary TMN superconductors and main-group nitride semiconductors along certain crystallographic orientations. Overall, these results highlight MgxTM1−xN as a class of materials combining the semiconducting properties of main-group wurtzite nitrides and rocksalt structure of superconducting transition-metal nitrides.

scholarly journals Photothermal Microscopy: Imaging the Optical Absorption of Single Nanoparticles and Single Molecules

ACS Nano ◽  
2020 ◽  
Vol 14 (12) ◽  
pp. 16414-16445
Author(s):  
Subhasis Adhikari ◽  
Patrick Spaeth ◽  
Ashish Kar ◽  
Martin Dieter Baaske ◽  
Saumyakanti Khatua ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Single Molecules ◽  
Microscopy Imaging ◽  
Photothermal Microscopy

scholarly journals Bayesian MEG time courses with fMRI priors

2021 ◽  
Author(s):  
Yingying Wang ◽  
Scott K. Holland
Keyword(s):  
Spatial Resolution ◽  
Spatial Information ◽  
Brain Activity ◽  
Source Reconstruction ◽  
Good Spatial Resolution ◽  
Surgical Evaluation ◽  
Neuroimaging Data ◽  
Excellent Spatial Resolution ◽  
Time Courses ◽  
Evoked Activity

AbstractMagnetoencephalography (MEG) records brain activity with excellent temporal and good spatial resolution, while functional magnetic resonance imaging (fMRI) offers good temporal and excellent spatial resolution. The aim of this study is to implement a Bayesian framework to use fMRI data as spatial priors for MEG inverse solutions. We used simulated MEG data with both evoked and induced activity and experimental MEG data from sixteen participants to examine the effectiveness of using fMRI spatial priors in MEG source reconstruction. For simulated MEG data, incorporating the prior information from fMRI increased the spatial resolution of MEG source reconstruction by 3 mm on average. For experimental MEG data, fMRI spatial information reduced the spurious clusters for evoked activity and showed more left-lateralized activation pattern for induced activity. The use of fMRI spatial priors greatly reduced location error for induced source in MEG data. Our results provide empirical evidence that the use of fMRI spatial priors improves the accuracy of MEG source reconstruction. The combined MEG and fMRI approach can provide neuroimaging data with better spatial and temporal resolutions to add another perspective to our understanding of the neurobiology of language. The potential clinical applications include pre-surgical evaluation of language function for epilepsy patients and evaluation of language network for children with language disorders.

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