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.

Contamination-Free TEM for High-Resolution Imaging of Soft Materials

2010 ◽  
Vol 18 (3) ◽  
pp. 32-35 ◽  
Author(s):  
Shin Horiuchi ◽  
Takeshi Hanada
Keyword(s):  
Electron Beam ◽  
Energy Loss ◽  
Thin Foil ◽  
Soft Materials ◽  
Mean Free Path ◽  
Loss Peak ◽  
Irradiation Period ◽  
Resolution Imaging ◽  
Electron Energy Loss ◽  
Beam Damage

Element-selective imaging and analysis at atomic resolution have become possible by the recent advancements in TEM and STEM. However, the spatial resolution in images of soft materials can be limited by electron beam damage and/or contamination. This contamination is a carbonaceous layer deposited on the specimen surface as a result of electron bombardment. Beam-induced specimen contamination is caused by polymerization of hydrocarbons that are present in a TEM specimen chamber. The electron beam reacts with stray hydrocarbons in the beam's path to create hydrocarbon ions, which then condense and form carbon-rich polymerized film on the area being irradiated. Figure 1a shows contamination spots created on a carbon thin foil by illuminating a beam with an intensity of 5.6 × 104 el/nm·s at an accelerating voltage of 200 kV. The thickness of the contamination spots can be estimated by electron energy-loss spectroscopy (EELS). With increase in the irradiation period, the intensity of the zero-loss peak decreases, but the overall intensities in the energy-loss regions of the spectrum increase (Figure 1b). The thickness (D) can be estimated using the equation, D = Λ·ln(It/I0), where Λ is the total mean free path for inelastic scattering, and It and I0 are the integral intensities of the overall spectrum and the zero-loss peak, respectively. Using this equation, the thickness of the contamination was found to be about 600 nm with a 10-minute irradiation.

The limits of microanalytical information as set by electron-beam damage

1983 ◽  
Vol 41 ◽  
pp. 366-367
Author(s):  
M. S. Isaacson
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Electron Microscope ◽  
General Practitioner ◽  
Radiation Damage ◽  
To Come ◽  
Main Item ◽  
Electron Microscopist ◽  
Beam Damage

The task given to me was try to address how radiation damage limits the information that we can extract from a sample in the electron microscope and to somehow i11ucidate what is known about the mechanism of the damage itself. I am afraid that the tasks are more formidable than I first realized, and I shall not (in this paper) be able to come to definitive conclusions. However, the attempt will be made to tie together various observations and bits of knowledge from different areas which may not be familiar to the general practitioner of electron microscopy.The area of radiation damage in electron microscopy tends to be somewhat descriptive. After all, it is really not the main item on the microscopist's agenda, but rather happens to be the unfortunate consequence of the act of viewing the sample. One can liken the electron microscopist to someone who is ill. It is not too important why or how the illness occurred, but rather, how to remedy it.

Electron-beam damage and analysis at low temperature

1990 ◽  
Vol 48 (4) ◽  
pp. 806-807
Author(s):  
Yoshio Bando ◽  
Yoshizo Kitami ◽  
Masato Yokoyama
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Low Temperature ◽  
Mass Loss ◽  
Radiation Damage ◽  
Liquid Helium ◽  
Inorganic Materials ◽  
Specimen Holder ◽  
Analytical System ◽  
Beam Damage

Elemental analysis for beam-sensitive materials is limited by radiation damage due to inelastic scattering of electrons. The amorphization and the mass loss often occure during the observation under a focused electron beam. It has been so far understood that the electron beam damage is effectively reduced by decreasing the specimen temperature. The cryo-electron microscope using liquid helium colled specimen holder is useful to minimize the radiation damage of the beam-sentitive materials. In the present paper, we have studied the radiation damage of various insulating inorganic materials in terms of the rate of the amorphization and the selective mass loss, which are observed at a room temperature (300K) and a low temperature (20K). All measurements are performed on a JEM-4000FX high-resolution analytical electron microscope with full analytical system. The specimen fragments placed on a holey carbon supporting grid are cooled down to about 20K. using a liquid helium specimen holder attached with a Be retainer.

The Energy Loss of 20 Kev Electrons in Biological Molecules

1970 ◽  
Vol 28 ◽  
pp. 262-263
Author(s):  
V. Crewe ◽  
M. Isaacson ◽  
D. Johnson
Keyword(s):  
Thin Films ◽  
High Resolution ◽  
Energy Loss ◽  
Biological Molecules ◽  
Scanning Microscopy ◽  
Characteristic Energy ◽  
Fast Electrons ◽  
Transmission Electron ◽  
Electron Scanning Microscopy ◽  
Contrast Mechanism

As part of a program to investigate the Interactions of fast electrons with thin specimens, we have measured the characteristic energy loss spectra of 20 kev electrons transmitted through thin films of various biological molecules. Such spectra are necessary In order to determine the potential of energy loss information as a contrast mechanism in high resolution transmission electron scanning microscopy.

Data Acquisition and Handling Unit for a Quantitative Use of Electron Energy Loss Spectroscopy

1977 ◽  
Vol 35 ◽  
pp. 232-233 ◽  
Author(s):  
P. Trebbia ◽  
P. Ballongue ◽  
C. Colliex
Keyword(s):  
Electron Microscope ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Single Channel ◽  
Detection System ◽  
Surface Barrier ◽  
Solid State Detector ◽  
Electrostatic Mirror ◽  
Electron Energy Loss

An effective use of electron energy loss spectroscopy for chemical characterization of selected areas in the electron microscope can only be achieved with the development of quantitative measurements capabilities.The experimental assembly, which is sketched in Fig.l, has therefore been carried out. It comprises four main elements.The analytical transmission electron microscope is a conventional microscope fitted with a Castaing and Henry dispersive unit (magnetic prism and electrostatic mirror). Recent modifications include the improvement of the vacuum in the specimen chamber (below 10-6 torr) and the adaptation of a new electrostatic mirror.The detection system, similar to the one described by Hermann et al (1), is located in a separate chamber below the fluorescent screen which visualizes the energy loss spectrum. Variable apertures select the electrons, which have lost an energy AE within an energy window smaller than 1 eV, in front of a surface barrier solid state detector RTC BPY 52 100 S.Q. The saw tooth signal delivered by a charge sensitive preamplifier (decay time of 5.10-5 S) is amplified, shaped into a gaussian profile through an active filter and counted by a single channel analyser.

Modification of the Electron Microscope for Investigation of Fully Hydrated Biological Specimens

1969 ◽  
Vol 27 ◽  
pp. 418-419 ◽  
Author(s):  
R. C. Moretz ◽  
D. F. Parsons
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Structural Damage ◽  
Lower Percentage ◽  
Vacuum Drying ◽  
Total Removal ◽  
Total Absence ◽  
Biological Studies ◽  
Electron Microscopes ◽  
Beam Damage

Short lifetime or total absence of electron diffraction of ordered biological specimens is an indication that the specimen undergoes extensive molecular structural damage in the electron microscope. The specimen damage is due to the interaction of the electron beam (40-100 kV) with the specimen and the total removal of water from the structure by vacuum drying. The lower percentage of inelastic scattering at 1 MeV makes it possible to minimize the beam damage to the specimen. The elimination of vacuum drying by modification of the electron microscope is expected to allow more meaningful investigations of biological specimens at 100 kV until 1 MeV electron microscopes become more readily available. One modification, two-film microchambers, has been explored for both biological and non-biological studies.

Probing the Chemistry and Spectroscopy of Radiation-Sensitive Polymers by Parallel-Detection EELS

1990 ◽  
Vol 48 (2) ◽  
pp. 34-35
Author(s):  
E. G. Rightor ◽  
G. P. Young
Keyword(s):  
Electron Beam ◽  
Bisphenol A ◽  
Energy Loss ◽  
Parallel Detection ◽  
Commercial Grade ◽  
Incident Electron Beam ◽  
Ptfe Sample ◽  
Spectroscopic Information ◽  
Edge Features ◽  
Electron Energy Loss

Investigation of neat polymers by TEM is often thwarted by their sensitivity to the incident electron beam, which also limits the usefulness of chemical and spectroscopic information available by electron energy loss spectroscopy (EELS) for these materials. However, parallel-detection EELS systems allow reduced radiation damage, due to their far greater efficiency, thereby promoting their use to obtain this information for polymers. This is evident in qualitative identification of beam sensitive components in polymer blends and detailed investigations of near-edge features of homopolymers.Spectra were obtained for a poly(bisphenol-A carbonate) (BPAC) blend containing poly(tetrafluoroethylene) (PTFE) using a parallel-EELS and a serial-EELS (Gatan 666, 607) for comparison. A series of homopolymers was also examined using parallel-EELS on a JEOL 2000FX TEM employing a LaB6 filament at 100 kV. Pure homopolymers were obtained from Scientific Polymer Products. The PTFE sample was commercial grade. Polymers were microtomed on a Reichert-Jung Ultracut E and placed on holey carbon grids.

Electron energy loss spectroscopy of diamond-like carbon thin films

1992 ◽  
Vol 50 (2) ◽  
pp. 1272-1273
Author(s):  
J. Kulik ◽  
Y. Lifshitz ◽  
G.D. Lempert ◽  
S. Rotter ◽  
J.W. Rabalais ◽  
...  
Keyword(s):  
Thin Films ◽  
Energy Loss ◽  
Electron Energy ◽  
Ion Beam ◽  
Diamond Like Carbon ◽  
Ion Beam Deposition ◽  
Chemistry Research ◽  
Carbon Thin Films ◽  
Electron Energy Loss ◽  
Beam Deposition

Carbon thin films with diamond-like properties have generated significant interest in condensed matter science in recent years. Their extreme hardness combined with insulating electronic characteristics and high thermal conductivity make them attractive for a variety of uses including abrasion resistant coatings and applications in electronic devices. Understanding the growth and structure of such films is therefore of technological interest as well as a goal of basic physics and chemistry research. Recent investigations have demonstrated the usefulness of energetic ion beam deposition in the preparation of such films. We have begun an electron microscopy investigation into the microstructure and electron energy loss spectra of diamond like carbon thin films prepared by energetic ion beam deposition.The carbon films were deposited using the MEIRA ion beam facility at the Soreq Nuclear Research Center in Yavne, Israel. Mass selected C+ beams in the range 50 to 300 eV were directed onto Si {100} which had been etched with HF prior to deposition.

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