No (643)
Used filters
(3)
Number of found documents:
643
Published from
to
STEM modes in SEM
Konvalina, Ivo; Paták, Aleš; Mikmeková, Eliška; Mika, Filip; Müllerová, Ilona
2018 - English
The segmented semiconductor STEM detector in the Magellan 400 FEG SEM microscope\n(https://www.fei.com/) is used to detect transmitted electrons (TEs) and allows observing\nsamples in four imaging modes. Two modes of objective lens, namely high resolution (HR)\nand ultra-high resolution (UHR), differ by their resolution and by the presence or absence of\na magnetic field around the sample. If the beam deceleration (BD) mode is chosen, then\nan electrostatic field around the sample is added and two further microscope modes HR + BD\nand UHR + BD, become available. Trajectories of TEs are studied with regard to their angular\nand energy distribution in each mode in this work.\n
Keywords:
SEM; STEM
Available at various institutes of the ASCR
STEM modes in SEM
The segmented semiconductor STEM detector in the Magellan 400 FEG SEM microscope\n(https://www.fei.com/) is used to detect transmitted electrons (TEs) and allows observing\nsamples in four imaging ...
Creation of electron vortex beams using the holographic reconstruction method in a scanning electron microscope
Řiháček, Tomáš; Horák, M.; Schachinger, T.; Matějka, Milan; Mika, Filip; Müllerová, Ilona
2018 - English
Electron vortex beams (EVB) were theoretically predicted in 2007 and first experimentally\ncreated in 2010. Although they attracted attention of many researchers, their\ninvestigation takes place almost solely in connection with transmission electron microscopes (TEM). On the other hand, although scanning electron microscopes (SEM) may provide some advantages for EVB applications, only little attention has been dedicated to them. Therefore, the aim of this work is to create electron vortices in SEM at energies of several keV.
Keywords:
electron vortex beams; scanning electron microscopy; electron diffraction
Available at various institutes of the ASCR
Creation of electron vortex beams using the holographic reconstruction method in a scanning electron microscope
Electron vortex beams (EVB) were theoretically predicted in 2007 and first experimentally\ncreated in 2010. Although they attracted attention of many researchers, their\ninvestigation takes place ...
Locking in on large volume light-sheet microscopy
Vettenburg, T.; Dalgarno, H.I.C.; Nylk, J.; Coll-Lladó, C.; Ferrier, D.E.K.; Čižmár, Tomáš; Gunn-Moore, F.J.; Dholakia, K.; Corral, A.; Rodriguez-Pulido, A.; Flors, C.; Ripoll, J.
2018 - English
Fluorescence light-sheet microscopy is increasingly adopted by developmental biologists to study how cells divide and differentiate to form organs and even entire organisms. The lightsheet microscope differs from a conventional microscope in that the specimen is illuminated by a plane of light orthogonal to the detection axis, thus keeping the out-of-focus areas dark while minimizing any potentially detrimental exposure of the sample. The light-sheet microscope has been found to be the ideal instrument for long-term and non-invasive studies of intact, and therefore three-dimensional, fluorescent samples.
Keywords:
cellular imaging; fluorescence imaging; light-sheet microscopy
Available at various institutes of the ASCR
Locking in on large volume light-sheet microscopy
Fluorescence light-sheet microscopy is increasingly adopted by developmental biologists to study how cells divide and differentiate to form organs and even entire organisms. The lightsheet microscope ...
Silver micro drop structured twice around the earth
Meluzín, Petr; Tryhuk, V.; Horáček, Miroslav; Knápek, Alexandr; Krátký, Stanislav; Matějka, Milan; Kolařík, Vladimír
2018 - English
Planar micro structuring of thin metallic layers allows to achieve required surface properties of metallic layers covering bulk materials. Recently, the arrangement of micro holes or pillars placed around the primary spiral according to a phyllotactic model was presented. This deterministically aperiodic planar arrangement was used for benchmarking purposes of the e-beam writer patterning. This arrangement based on single primary spiral and a variety of derived secondary spirals has several interesting properties. One of them is a very low ratio between the area populated by individual micro elements and the length of the primary phyllotactic spiral. This paper presents analysis of the phyllotactic spiral length and the rising gradient at the spiral outer edge. The practical part of the presented work deals with the patterning of a thin silver layer deposited on the silicon or glass substrates using e-beam pattern generation, lithography techniques and related technologies. An interesting impact of the mentioned spiral properties on the e-beam writing strategies and the exposure ordering strategy are also discussed.
Keywords:
metallic thin layer; planar surface structure; phyllotactic spiral; e-beam writer
Available at various institutes of the ASCR
Silver micro drop structured twice around the earth
Planar micro structuring of thin metallic layers allows to achieve required surface properties of metallic layers covering bulk materials. Recently, the arrangement of micro holes or pillars placed ...
Structure investigation of hydrogels using a cryo-SEM
Adámková, Kateřina; Hrubanová, Kamila; Samek, Ota; Trudičová, M.; Sedláček, P.; Krzyžánek, Vladislav
2018 - English
Hydrogels can be characterized as elastic hydrophilic polymer chains connected in network\nwhich are able to swell notably when exposed to aqueous media by absorbing considerable\namounts of water. Besides being a constituent of living organisms, nowadays, there are\nvarious fields hydrated polymers (e.g. polyvinyl alcohol, collagen, and starch) can be utilized\n– in both biological and non-biological form. Classic examples of such applications are\nhuman health and cosmetics (contact lenses, wound healing dressings and artificial\nreplacement tissues – skin, arterial grafts, cornea and spinal disc replacement), pharmacy\n(drug delivery systems), bioengineering, food industry, agriculture etc. Also, hydrogels\ncan reversibly change their shape when being exposed to a temperature change.
Keywords:
hydrogel; cryo-SEM; raman spectroscopy; high pressure freezing; freeze-etching; hyaluronic acid; agarose
Available at various institutes of the ASCR
Structure investigation of hydrogels using a cryo-SEM
Hydrogels can be characterized as elastic hydrophilic polymer chains connected in network\nwhich are able to swell notably when exposed to aqueous media by absorbing considerable\namounts of water. ...
Thermal desorption spectroscopy in prototype furnace for chemical vapor deposition
Průcha, Lukáš; Daniel, Benjamin; Piňos, Jakub; Mikmeková, Eliška
2018 - English
Cleaning of the sample surfaces is crucial for scanning electron microscopy, especially for\nlow energy electron microscopy or for the deposition of thin layers, such as graphene,\nwhere surface has to be well prepared. In the best case, every unwanted particle should be\ncleaned from the sample surface for best low energy electron microscopy observation or thin\nfilm deposition. Unfortunately, the standard cleaning procedures can leave residues on the\nsample surface. This work is focused on thermal desorption spectroscopy (TDS). TDS is a method of observing desorbed molecules from a sample surface during the increase of\ntemperature of the sample. The aim of this study was to determine optimum conditions:\ntemperature and time, to achieve clean surfaces in the shortest time.
Keywords:
thermal desorption spectroscopy; CVD; surface cleaning; silicon
Available at various institutes of the ASCR
Thermal desorption spectroscopy in prototype furnace for chemical vapor deposition
Cleaning of the sample surfaces is crucial for scanning electron microscopy, especially for\nlow energy electron microscopy or for the deposition of thin layers, such as graphene,\nwhere surface has ...
Electron optical properties of a new low-energy scanning electron microscope with beam separator
Radlička, Tomáš; Kolařík, V.; Oral, Martin
2018 - English
The low energy scanning electron microscope (SEM) which is currently at the Institute of\nScientific Instruments, suffers from low resolution and suboptimal detections systems. In the cathode lens regime, signal electrons are accelerated by the electric field between the sample and the objective lens, getting collimated. Those with low emission angles get through the bore in the BSE detector into the objective lens and cannot be detected by the available detectors now. The information about the sample provided by these electrons is lost, which limits our microscopy methods.\nThese two limitations are to be overcome with a new low-energy SEM, which was developed\nat Delong Instruments. It consists of a field emission gun with the energy width of 0.8 eV, a magnetic condenser lens, and an electrostatic triode objective lens. The acceleration voltage is 5 kV. The sample stage can be biased at up to -5 kV to provide low landing energy without strong decrease of the resolution – the effect of the cathode lens. A beam separator is placed in front of the deflection system for the detection of the signal electrons that get to the column. In a combination with standard detectors and cathode lens, it allows detecting all\nkinds of signal electrons.
Keywords:
low energy scanning electron microscopy; beam separation; aberrations
Available at various institutes of the ASCR
Electron optical properties of a new low-energy scanning electron microscope with beam separator
The low energy scanning electron microscope (SEM) which is currently at the Institute of\nScientific Instruments, suffers from low resolution and suboptimal detections systems. In the cathode lens ...
Inelastic mean free path from raw data measured by low-energy electrons time-of-flight spectrometer
Zouhar, Martin; Radlička, Tomáš; Oral, Martin; Konvalina, Ivo
2018 - English
The inelastic mean free path (IMFP) is a key parameter of electron transport in a solid. With\nthe rise of so-called meta-materials, materials of specific shape, such as 2D crystals, or\nmaterials with tailored functionality for next-generation electronic devices, the investigation\nof the IMFP is still topical and of high importance. This is true especially at low energies, landing energy of electrons below 100 eV, that are hard to study using well established\ntechniques of electron spectroscopy.
Keywords:
electron microscopy; time of flight; inelastic mean free path; low energy
Available at various institutes of the ASCR
Inelastic mean free path from raw data measured by low-energy electrons time-of-flight spectrometer
The inelastic mean free path (IMFP) is a key parameter of electron transport in a solid. With\nthe rise of so-called meta-materials, materials of specific shape, such as 2D crystals, or\nmaterials ...
Optical binding of polystyrene particles in tractor beam
Damková, Jana; Chvátal, Lukáš; Oulehla, Jindřich; Ježek, Jan; Brzobohatý, Oto; Zemánek, Pavel
2018 - English
The motion of a particle illuminated by a laser beam is usually driven by the photon flow due\nto the radiation pressure and therefore for particle trapping, one has to employ gradient forces. But in a tractor beam, objects are illuminated by the uniform light intensity and even so they can be pulled against the beam propagation. There have been developed several techniques how to create such a tractor beam. In our case, the tractor beam is created by two identical Gaussian beams that interfere under the defined angle. It creates the\nstanding wave, where in the transversal plane the particle is trapped by means of the gradient\nforce, but in the total beam propagation direction, the particle manipulation is driven by the non-conservative force. It is remarkable that this force can for the specific combinations of\nparameters pull the micro-particle against the beam propagation. This kind of behavior is\nbecause of the particle scattering where the majority of the incident photons is scattered in the forward direction and, based on the principle of action and reaction, the transfer of\nmomentum leads to a backward movement of the object. The pushing and pulling force is\nsensitive to the polarization of the laser beam, its incident angle and the particle size so this\ntechnique can be used for example for sorting of objects of different sizes.
Keywords:
optical binding; self-organization; optical force; tractor beam; holographic video microscopy
Available at various institutes of the ASCR
Optical binding of polystyrene particles in tractor beam
The motion of a particle illuminated by a laser beam is usually driven by the photon flow due\nto the radiation pressure and therefore for particle trapping, one has to employ gradient forces. But in ...
Field emission from W5O14 nanowires
Saqib, M.; Knápek, Alexandr; Jelenc, J.; Pirker, L.
2018 - English
The W5O14 (O/W=2.8) nanowires are metallic oxides with specific resistivity of 25 microOhm/cm and\ndiameters bellow 100 nm [1]. They were synthesized by iodine transport method using nickel\nas a growth promoter and WO3 as source of tungsten and oxygen. The field emission\ncharacteristics of single nanowires [2] and the films composed of these nanowires have been\nreported [3]. The emitting current densities up to 6.4 mA/cm2 have been obtained at relatively\nlow average electric field of about 3 V/Ohm*m. The samples were allowed to emit for more than\n100 hours without showing significant decays of the emitting current and without substantial\ncurrent oscillations. Here, we present field emission properties of single W5O14 nanowires\nexposed to two ranges of average electric fields (0.7–0.85 V/Ohm*m and up to 37–39 V/Ohm*m.
Keywords:
field emission; W5O14 nanowires
Available at various institutes of the ASCR
Field emission from W5O14 nanowires
The W5O14 (O/W=2.8) nanowires are metallic oxides with specific resistivity of 25 microOhm/cm and\ndiameters bellow 100 nm [1]. They were synthesized by iodine transport method using nickel\nas a ...
NRGL provides central access to information on grey literature produced in the Czech Republic in the fields of science, research and education. You can find more information about grey literature and NRGL at service web
Send your suggestions and comments to nusl@techlib.cz
Provider
Other bases