scholarly journals Damage-free vibrational spectroscopy of biological materials in the electron microscope

2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Peter Rez ◽  
Toshihiro Aoki ◽  
Katia March ◽  
Dvir Gur ◽  
Ondrej L. Krivanek ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Radiation Damage ◽  
Vibrational Spectroscopy ◽  
Biological Materials ◽  
High Energy ◽  
Vibrational Modes ◽  
Native State ◽  
Organic Functional Groups ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

Abstract Vibrational spectroscopy in the electron microscope would be transformative in the study of biological samples, provided that radiation damage could be prevented. However, electron beams typically create high-energy excitations that severely accelerate sample degradation. Here this major difficulty is overcome using an ‘aloof’ electron beam, positioned tens of nanometres away from the sample: high-energy excitations are suppressed, while vibrational modes of energies <1 eV can be ‘safely’ investigated. To demonstrate the potential of aloof spectroscopy, we record electron energy loss spectra from biogenic guanine crystals in their native state, resolving their characteristic C–H, N–H and C=O vibrational signatures with no observable radiation damage. The technique opens up the possibility of non-damaging compositional analyses of organic functional groups, including non-crystalline biological materials, at a spatial resolution of ∼10 nm, simultaneously combined with imaging in the electron microscope.

Titanium-Suicide Contacts on GaAs

1985 ◽  
Vol 43 ◽  
pp. 370-371
Author(s):  
Z. Liliental ◽  
A. Wakita ◽  
C. Kocot ◽  
J. Washburn ◽  
R. Gronsky
Keyword(s):  
Heat Treatment ◽  
Electron Microscope ◽  
Cross Section ◽  
Schottky Contacts ◽  
Electrical Parameters ◽  
Treatment Procedure ◽  
X Ray ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra ◽  
Heat Treatment Procedure

Successful use of titanium silicides as contacts on Si suggested the possibility of their application as Schottky contacts on GaAs. One composition of Ti:Si with the ratio 1:3 annealed for 5 sec at 875°C was found to result in good Schottky contacts. The barrier height and ideality factor were 0.8 eV and 1.15, respectively. The same heat treatment procedure for the composition of Ti:Si 1:2 did not give satisfactory electrical parameters.Cross section samples were prepared from these contacts for both compositions and were examined in a JEOL 200 CX electron microscope. Energy dispersive X-ray (EDX) and electron energy loss spectra (EELS) were taken using a Phillips 400 FEG electron microscope at 100 KV accelerating voltage.As-deposited structures with Ti:Si ratios 1:2 and 1:3 consisted of four alternate Ti and Si layers with different thicknesses. The interface of the first Ti layer with GaAs was very flat and abrupt for both compositions.

Electron spectroscopic imaging and analysis of electron energy loss spectra with an energy filtering Electron Microscope

1989 ◽  
Vol 47 ◽  
pp. 404-405
Author(s):  
John J. Godleski ◽  
Rebecca C. Stearns ◽  
Emil J. Millet
Keyword(s):  
Electron Microscope ◽  
Energy Loss ◽  
Electron Energy ◽  
Scintillation Detector ◽  
Oxide Particle ◽  
Leading Edge ◽  
Hard Disk ◽  
Energy Filtering ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

The Zeiss CEM902, energy filtering electron microscope, can be used to image the structure of unstained 30 nm sections of biologic materials, to image the distribution of selected elements in such sections, and to determine electron energy loss spectra (EELS) of elements in areas as small as 10 nm. Although the integrated computer in the latest version of the CEM902 can collect and display signals from the scintillation detector for recording EELS, our instrument did not have this capability. Therefore, we have added a Leading Edge Model D personal computer with a 20 Mbyte hard disk, Hercules compatible graphics display adapter, and a programmable gain analog to digital converter board (Metrabyte DAS16-G1) to collect and analyze voltage signals corresponding to changes in accelerating voltage and changes in the signal from the photomultiplier tube (PMT) of the scintillation detector. With this board, the gain on the PMT channel is dynamically adjusted for optimal resolution. Software is designed to monitor and display voltages, store data on the hard disk, display spectra with adjustable axes, as well as subtract spectra and determine areas beneath regions of interest.Canine alveolar macrophages with ingested cobalt oxide particles were fixed with 2.5% glutaraldehyde in 0.164M phosphate buffer, post-fixed in 1% OsO4 in 0.lM Na cacodylate buffer, dehydrated through alcohols, embedded in araldite, and sectioned at 30nm. Sections were assessed with our CEM902 as described above. The spectral range of 500 to 900 electron volts while focused on acobalt oxide particle at 20,000x is illustrated in Figure 1 .

scholarly journals Erratum: Damage-free vibrational spectroscopy of biological materials in the electron microscope

2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Peter Rez ◽  
Toshihiro Aoki ◽  
Katia March ◽  
Dvir Gur ◽  
Ondrej L. Krivanek ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Vibrational Spectroscopy ◽  
Biological Materials

Inner Shell Ionization by 60 keV Electrons, Application to Microanalysis

1975 ◽  
Vol 33 ◽  
pp. 126-127
Author(s):  
Y. Kihn ◽  
J. Sevely ◽  
B. Jouffrey
Keyword(s):  
Electron Microscope ◽  
Energy Loss ◽  
Electron Energy ◽  
Selection Rules ◽  
First Approximation ◽  
Inner Shell Ionization ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra ◽  
Shell Ionization

By using a Castaing-Henry filtering device adapted on a Siemens Elmiskop I electron microscope, we have directly observed plasmon and inner shell excitations by 60 keV electrons on electron energy loss spectra. Inner shell excitation edges have been detected up to 1900 eV.By comparing L and K inner shell excitation profiles in the case of Magnesium, Aluminium and Silicon, it is concluded that the optical selection rules, △1 = ±1, explain the shape of the spectrum after the edge in a first approximation.

Reduction in Radiation Damage at Low Temperature

1980 ◽  
Vol 38 ◽  
pp. 682-683
Author(s):  
R. F. Egerton
Keyword(s):  
Low Temperature ◽  
Energy Loss ◽  
Radiation Damage ◽  
Heat Radiation ◽  
Thin Sample ◽  
Dose Rates ◽  
Specimen Holder ◽  
Electron Energy Loss ◽  
O 10 ◽  
Electron Energy Loss Spectra

Previous low-temperature measurements of radiation damage in organic materials have been based on the diffraction pattern, changes in total scattering power, background in the X-ray emission spectrum or the O - 10 eV region of electron energy-loss spectra. Here we observe instead the 200-600 eV region of the energy-loss spectrum, which contains information relating to the concentration of carbon, nitrogen and oxygen present in a thin sample. Specimens were irradiated by 80 keV electrons in a JEM IOOB transmission microscope fitted with a specially-constructed specimen holder which could be cooled to 77°K by circulation of liquid nitrogen. Cooled apertures above and below the specimen reduce heat radiation and possible condensation of residual gases from the surroundings. For the dose rates (<0.4 mA cm"2) and specimen thicknesses (< 50 nm) employed here, temperature rise due to the electron beam is expected to be negligible7.

Application-driven computerisation of the energy filtering Electron Microscope for imaging and analysis

1989 ◽  
Vol 47 ◽  
pp. 58-59
Author(s):  
R. Bauer ◽  
W. Probst ◽  
G. Lamprecht
Keyword(s):  
Electron Microscope ◽  
Chemical Composition ◽  
Energy Loss ◽  
Statistical Information ◽  
Chemical Information ◽  
Elemental Distribution ◽  
Energy Filtering ◽  
Physical And Chemical ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

An Energy Filtering Electron Microscope (EFEM) with an integrated imaging energy loss spectrometer offers many different methodes for imaging and analysis. Thus there is a wealth of different information from a specimen. They are all related to the structure as well as to the physical and chemical composition of a specimen. There are e.g. geometrical and statistical information from brightfield and darkfield images, information about crystalline structures from diffraction images, chemical information from electron energy loss spectra and highly resolved elemental distribution images. Most of this information is detail information not final results. To get final results, detail information have to be related and processed. To do this reliably and economically it is important to have a powerful and flexible computer system permanently available on the microscope to record, enhance, process, evalute, analyse, and store images, spectra and data. An important point is the use of the computer capabilities to perform automatic control of the microscope.

Electron Beam Damage in Biological Molecules

1970 ◽  
Vol 28 ◽  
pp. 264-265
Author(s):  
A. V. Crewe ◽  
M. Isaacson ◽  
D. Johnson
Keyword(s):  
Thin Films ◽  
Electron Beam ◽  
Electron Microscope ◽  
Energy Loss ◽  
Radiation Damage ◽  
Biological Molecules ◽  
Contrast Mechanism ◽  
Series Of Experiments ◽  
Electron Energy Loss ◽  
Beam Damage

In order to determine the potential of electron energy loss Information as a contrast mechanism in transmission scanning microscopy, as well as to better understand the interaction of electrons with the specimen in any electron microscope, more knowledge is needed concerning the damage produced in the specimen by the beam. This is especially true in biological specimens where the radiation damage is very significant, but not well understood. To investigate this problem, we have begun a series of experiments studying the effects of the passage of a ∼20 kv electron beam through thin films of important biological molecules.

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