scholarly journals Performance evaluation of a high-resolution parallel-plate differential mobility analyzer

2009 ◽  
Vol 9 (7) ◽  
pp. 2419-2429 ◽  
Author(s):  
J. P. Santos ◽  
E. Hontañón ◽  
E. Ramiro ◽  
M. Alonso
Keyword(s):  
High Resolution ◽  
Parallel Plate ◽  
High Sensitivity ◽  
Resolving Power ◽  
Narrow Slit ◽  
Differential Mobility Analyzer ◽  
Differential Mobility ◽  
Rectangular Slit ◽  
Continuous Stream ◽  
Ion Mobility Spectra

Abstract. A high-resolution differential mobility analyzer (DMA), specially designed for (i) the measurement of ion mobility spectra, and (ii) the generation of a continuous stream of monomobile ions, has been developed and tested. The apparatus consists of two parallel-plate electrodes between which an electric field is applied. The test ion stream flows into the instrument through a narrow rectangular slit made in one of the electrodes, and migrates toward the other electrode driven by the applied field, while being transported by a stream of clean air which flows parallel to the plates at Reynolds number between 2×104 and 9×104 in laminar flow conditions. The collector electrode contains also a narrow slit through which ions of the desired mobility are withdrawn out of DMA. The classified ion current is measured with a high-sensitivity electrometer having a noise level around 0.1 fA. The theory behind the DMA operation is first discussed, focusing on the special case of parallel-plate geometry. Some generic results showing the stability and repeatability of the measurements and the resolving power of the instrument are presented next. The last part of the paper deals with the application of the apparatus to the study of the effect of humidity and aging time on the mobility spectra of air ions generated by a low-activity 241Am source.

scholarly journals Performance evaluation of a high-resolution parallel-plate differential mobility analyzer

2008 ◽  
Vol 8 (5) ◽  
pp. 17631-17660 ◽  
Author(s):  
J. P. Santos ◽  
E. Hontañón ◽  
E. Ramiro ◽  
M. Alonso
Keyword(s):  
High Resolution ◽  
Parallel Plate ◽  
High Sensitivity ◽  
Resolving Power ◽  
Narrow Slit ◽  
Differential Mobility Analyzer ◽  
Differential Mobility ◽  
Rectangular Slit ◽  
Continuous Stream ◽  
Ion Mobility Spectra

Abstract. A high-resolution differential mobility analyzer (DMA), specially designed for (i) the measurement of ion mobility spectra, and (ii) the generation of a continuous stream of monomobile ions, has been developed and tested. The apparatus consists of two parallel-plate electrodes between which an electric field is applied. The test ion stream flows into the instrument through a narrow rectangular slit made in one of the electrodes, and migrates toward the other electrode driven by the applied field, while being transported by a stream of clean air which flows parallel to the plates at Reynolds number between 2×104 and 9×104 in laminar flow conditions. The collector electrode contains also a narrow slit through which ions of the desired mobility are withdrawn out of DMA. The classified ion current is measured with a high-sensitivity electrometer having a noise level around 0.1 fA. The theory behind the DMA operation is first discussed, focusing on the special case of parallel-plate geometry. Some generic results showing the stability and repeatability of the measurements and the resolving power of the instrument are presented next. The last part of the paper deals with the application of the apparatus to the study of the effect of humidity and aging time on the mobility spectra of air ions generated by a low-activity 241Am source.

scholarly journals Characterization of a high-resolution supercritical differential mobility analyzer at reduced flow rates

2018 ◽  
Vol 52 (11) ◽  
pp. 1332-1343 ◽  
Author(s):  
Runlong Cai ◽  
Michel Attoui ◽  
Jingkun Jiang ◽  
Frans Korhonen ◽  
Jiming Hao ◽  
...  
Keyword(s):  
High Resolution ◽  
Differential Mobility Analyzer ◽  
Differential Mobility ◽  
Flow Rates ◽  
Reduced Flow

scholarly journals High-resolution X-ray spectroscopy of astrophysical plasmas with X-ray microcalorimeters

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Yuichiro Ezoe ◽  
Takaya Ohashi ◽  
Kazuhisa Mitsuda
Keyword(s):  
High Resolution ◽  
Spectral Resolution ◽  
High Sensitivity ◽  
Resolving Power ◽  
High Spectral Resolution ◽  
High Resolution Spectroscopy ◽  
Astrophysical Plasmas ◽  
X Ray ◽  
New Findings ◽  
Perseus Cluster

AbstractHigh spectral resolution with a resolving power, $$E/\Delta E \gtrsim 1000$$ E / Δ E ≳ 1000 at 6 keV, is now available in X-ray astronomy. X-ray observations are particularly effective for plasma studies since major atomic transitions appear as spectral features in the X-ray band. High-resolution spectroscopy enables us to probe a wide variety of astrophysical plasmas, which are not obtainable from ground experiments, regarding their temperature, density, magnetic field, gravity, and velocity. In this review, we describe what are the X-ray emitting plasmas in the Universe, along with basic plasma diagnostics, and depict historical development of the techniques used for the X-ray spectroscopy. We outline the X-ray microcalorimeter instrument, soft X-ray spectrometer (SXS), onboard the ASTRO-H satellite. Despite the short lifetime of the satellite in orbit for about a month, observations with the SXS have shown the remarkable power of high-resolution spectroscopy in X-ray astronomy. Observed spectrum of the hot plasma in the core region of the Perseus cluster showed He-like Fe K-line to be clearly resolved into resonance, forbidden and intercombination lines for the first time. The line width indicates that the turbulent pressure amounts to only 4% of the thermal pressure of the plasma. We also describe new findings and constraints obtained from the superb spectrum of the Perseus cluster, which all indicate a great potential of X-ray spectroscopy. The recovery of the spectroscopy science of ASTRO-H is aimed at with XRISM, a Japanese mission planned for launch in early 2020s. In further future, Athena will expand the rich science with its high sensitivity and spectral resolution in early 2030s.

scholarly journals Characterization of a Herrmann-type high-resolution differential mobility analyzer

2016 ◽  
Vol 50 (3) ◽  
pp. 222-229 ◽  
Author(s):  
J. Kangasluoma ◽  
M. Attoui ◽  
F. Korhonen ◽  
L. Ahonen ◽  
E. Siivola ◽  
...  
Keyword(s):  
High Resolution ◽  
Differential Mobility Analyzer ◽  
Differential Mobility

The High Resolution Scanning Transmission Electron Microscope

1974 ◽  
Vol 32 ◽  
pp. 316-317
Author(s):  
A. V. Crewe
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
High Vacuum ◽  
Scanning Transmission Electron Microscope ◽  
Ultra High Vacuum ◽  
Resolving Power ◽  
Imaging Characteristics ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
The Moment

The high resolution STEM is now a fact of life. I think that we have, in the last few years, demonstrated that this instrument is capable of the same resolving power as a CEM but is sufficiently different in its imaging characteristics to offer some real advantages.It seems possible to prove in a quite general way that only a field emission source can give adequate intensity for the highest resolution^ and at the moment this means operating at ultra high vacuum levels. Our experience, however, is that neither the source nor the vacuum are difficult to manage and indeed are simpler than many other systems and substantially trouble-free.

An Analysis of Dissociation of Molecules in a High Resolution Electron Microscope

1973 ◽  
Vol 31 ◽  
pp. 486-487
Author(s):  
Mihir Parikh
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Cross Sections ◽  
Resolving Power ◽  
Peak Intensity ◽  
Molecular Film ◽  
Resolution Electron ◽  
Dissociation Cross Section ◽  
High Resolution Electron Microscope ◽  
The Stability

It is well known that the resolution of bio-molecules in a high resolution electron microscope depends not just on the physical resolving power of the instrument, but also on the stability of these molecules under the electron beam. Experimentally, the damage to the bio-molecules is commo ly monitored by the decrease in the intensity of the diffraction pattern, or more quantitatively by the decrease in the peaks of an energy loss spectrum. In the latter case the exposure, EC, to decrease the peak intensity from IO to I’O can be related to the molecular dissociation cross-section, σD, by EC = ℓn(IO /I’O) /ℓD. Qu ntitative data on damage cross-sections are just being reported, However, the microscopist needs to know the explicit dependence of damage on: (1) the molecular properties, (2) the density and characteristics of the molecular film and that of the support film, if any, (3) the temperature of the molecular film and (4) certain characteristics of the electron microscope used

Backscattered Electron Imaging of GaAs/AlGaAs Super Lattice Structures with an Ultra-High- Resolution SEM

1988 ◽  
Vol 46 ◽  
pp. 204-205
Author(s):  
Kazumichi Ogura ◽  
Michael M. Kersker
Keyword(s):  
High Resolution ◽  
Layer Structure ◽  
High Sensitivity ◽  
Beam Current ◽  
Electron Beam Current ◽  
Lattice Structures ◽  
Super Lattice ◽  
Different Types ◽  
Backscattered Electron ◽  
Electron Imaging

Backscattered electron (BE) images of GaAs/AlGaAs super lattice structures were observed with an ultra high resolution (UHR) SEM JSM-890 with an ultra high sensitivity BE detector. Three different types of super lattice structures of GaAs/AlGaAs were examined. Each GaAs/AlGaAs wafer was cleaved by a razor after it was heated for approximately 1 minute and its crosssectional plane was observed.First, a multi-layer structure of GaAs (100nm)/AlGaAs (lOOnm) where A1 content was successively changed from 0.4 to 0.03 was observed. Figures 1 (a) and (b) are BE images taken at an accelerating voltage of 15kV with an electron beam current of 20pA. Figure 1 (c) is a sketch of this multi-layer structure corresponding to the BE images. The various layers are clearly observed. The differences in A1 content between A1 0.35 Ga 0.65 As, A1 0.4 Ga 0.6 As, and A1 0.31 Ga 0.69 As were clearly observed in the contrast of the BE image.

Practical High Resolution Microscopy

1968 ◽  
Vol 26 ◽  
pp. 302-303
Author(s):  
P. A. Marsh ◽  
T. Mullens ◽  
D. Price
Keyword(s):  
High Resolution ◽  
Magnetic Fields ◽  
Low Frequency ◽  
Resolving Power ◽  
Careful Attention ◽  
Electron Microscopes ◽  
The Relationship ◽  
High Resolution Microscopy ◽  
New Facilities

It is possible to exceed the guaranteed resolution on most electron microscopes by careful attention to microscope parameters essential for high resolution work. While our experience is related to a Philips EM-200, we hope that some of these comments will apply to all electron microscopes.The first considerations are vibration and magnetic fields. These are usually measured at the pre-installation survey and must be within specifications. It has been our experience, however, that these factors can be greatly influenced by the new facilities and therefore must be rechecked after the installation is completed. The relationship between the resolving power of an EM-200 and the maximum tolerable low frequency interference fields in milli-Oerstedt is 10 Å - 1.9, 8 Å - 1.4, 6 Å - 0.8.

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