Experimental Absorption Coefficients of Resists and Biological Materials

1985 ◽  
Vol 43 ◽  
pp. 606-609
Author(s):  
D.M. Shinozaki ◽  
P.C. Cheng ◽  
K. Tan ◽  
J. Wm. McGowan
Keyword(s):  
Radiation Damage ◽  
Damage Mechanism ◽  
Biological Materials ◽  
Absorption Coefficients ◽  
X Ray ◽  
Long Wavelength ◽  
Image Recording ◽  
Direct Measurements ◽  
Using Data ◽  
Biological Component

The technique of soft x-ray contact imaging involves irradiating a polymer resist (the image recording medium) through a specimen with a microstructure of interest. The x-ray flux transmitted through the specimen is attenuated by the constituents of the microstructure, and the polymer resist and biological component and tissue suffer varying amounts of radiation damage. The amount of radiation damage in the resist depends on the absorbed energy and therefore is a function of the absorption coefficient of the resist and the flux incident on the resist. An understanding of the image formed in the resist, and the use of images for microchemical analysis depends on a quantitative measurement of absorption coefficients of both the resist and biological materials. It is possible to estimate the absorption behavior of materials using data from experiments on the gas phase of nitrogen, oxygen, etcetera. However direct measurements are particularly necessary near absorption edges such as at the carbon K edge where chemical effects are significant, and towards the long wavelength side of the soft x-ray region where the radiation damage mechanism is strongly affected by the molecular structure.

Synchrotron Radiation Damage Mechanism of X-Ray Mask Membranes Irradiated in Helium Environment

1992 ◽  
Vol 31 (Part 1, No. 12B) ◽  
pp. 4459-4462 ◽  
Author(s):  
Tomiyuki Arakawa ◽  
Hiroshi Okuyama ◽  
Koichi Okada ◽  
Hiroyuki Nagasawa ◽  
Tsutomu Syoki ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Radiation Damage ◽  
Damage Mechanism ◽  
X Ray

Effects of soft X-ray radiation damage on paraffin-embedded rat tissues supported on ultralene: a chemical perspective

2018 ◽  
Vol 25 (3) ◽  
pp. 848-856 ◽  
Author(s):  
Diana E. Bedolla ◽  
Andrea Mantuano ◽  
Arissa Pickler ◽  
Carla Lemos Mota ◽  
Delson Braz ◽  
...  
Keyword(s):  
Sample Preparation ◽  
Radiation Damage ◽  
Structural Changes ◽  
Damage Mechanism ◽  
Exposure Dose ◽  
Rat Tissues ◽  
Structural Morphology ◽  
X Ray ◽  
Tissue Lipids ◽  
Embedding Medium

Radiation damage is an important aspect to be considered when analysing biological samples with X-ray techniques as it can induce chemical and structural changes in the specimens. This work aims to provide new insights into the soft X-ray induced radiation damage of the complete sample, including not only the biological tissue itself but also the substrate and embedding medium, and the tissue fixation procedure. Sample preparation and handling involves an unavoidable interaction with the sample matrix and could play an important role in the radiation-damage mechanism. To understand the influence of sample preparation and handling on radiation damage, the effects of soft X-ray exposure at different doses on ultralene, paraffin and on paraffin-embedded rat tissues were studied using Fourier-transform infrared (FTIR) microspectroscopy and X-ray microscopy. Tissues were preserved with three different commonly used fixatives: formalin, glutaraldehyde and Karnovsky. FTIR results showed that ultralene and paraffin undergo a dose-dependent degradation of their vibrational profiles, consistent with radiation-induced oxidative damage. In addition, formalin fixative has been shown to improve the preservation of the secondary structure of proteins in tissues compared with both glutaraldehyde and Karnovsky fixation. However, conclusive considerations cannot be drawn on the optimal fixation protocol because of the interference introduced by both substrate and embedding medium in the spectral regions specific to tissue lipids, nucleic acids and carbohydrates. Notably, despite the detected alterations affecting the chemical architecture of the sample as a whole, composed of tissue, substrate and embedding medium, the structural morphology of the tissues at the micrometre scale is essentially preserved even at the highest exposure dose.

X-Ray Radiation Damage of Polymers in a Scanning Transmission X-Ray Microscope

1998 ◽  
Vol 4 (S2) ◽  
pp. 370-371
Author(s):  
T. Coffey ◽  
H. Ade ◽  
S. Urquhart ◽  
A.P. Smith
Keyword(s):  
Radiation Damage ◽  
Damage Mechanism ◽  
Polymer Structure ◽  
National Synchrotron Light Source ◽  
X Ray ◽  
Critical Dose ◽  
Scanning Transmission ◽  
Synchrotron Light ◽  
X Ray Absorption ◽  
The Continuum

We use the Scanning Transmission X-ray Microscope (STXM) at the National Synchrotron Light Source (NSLS) (1) to acquire images and spectra of polymers. To interpret data correctly, the effects X-ray radiation has on polymers must be understood. We have therefore started to characterize radiation damage in a variety of carbonyl containing polymers in two ways. First, we want to ascertain the critical dose for mass loss and the critical dose for the carbonyl in a variety of polymers and relate the critical dose to the polymer structure. (The critical dose is the radiation dose at which the optical density of the material is decreased by 1/e of its original value.) We also want to understand the damage mechanism. STXM acquires images and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectra by using X-ray photons to excite inner shell electrons to unoccupied valence orbitals or to the continuum.

Evaluation of Freezing Methods by Low Temperature X-Ray Diffraction

1977 ◽  
Vol 35 ◽  
pp. 330-333
Author(s):  
T. Gulik-Krzywicki ◽  
M.J. Costello
Keyword(s):  
Biological Materials ◽  
Molecular Organization ◽  
X Ray Diffraction ◽  
Glass Capillary ◽  
X Ray ◽  
Rate Dependent ◽  
Before And After ◽  
Freeze Etching ◽  
Diffraction Patterns ◽  
Set Up

Freeze-etching electron microscopy is currently one of the best methods for studying molecular organization of biological materials. Its application, however, is still limited by our imprecise knowledge about the perturbations of the original organization which may occur during quenching and fracturing of the samples and during the replication of fractured surfaces. Although it is well known that the preservation of the molecular organization of biological materials is critically dependent on the rate of freezing of the samples, little information is presently available concerning the nature and the extent of freezing-rate dependent perturbations of the original organizations. In order to obtain this information, we have developed a method based on the comparison of x-ray diffraction patterns of samples before and after freezing, prior to fracturing and replication.Our experimental set-up is shown in Fig. 1. The sample to be quenched is placed on its holder which is then mounted on a small metal holder (O) fixed on a glass capillary (p), whose position is controlled by a micromanipulator.

Studies of metaphase chromosomes in the scanning transmission x-ray microscope: Image fidelity, radiation damage and specimen preparation

1992 ◽  
Vol 50 (2) ◽  
pp. 1038-1039
Author(s):  
Shawn Williams ◽  
Xiaodong Zhang ◽  
Susan Lamm ◽  
Jack Van’t Hof
Keyword(s):  
Visible Light ◽  
Radiation Damage ◽  
Cross Section ◽  
Imaging Techniques ◽  
Dose Range ◽  
Specimen Preparation ◽  
X Rays ◽  
Metaphase Chromosomes ◽  
X Ray ◽  
Scanning Transmission

The Scanning Transmission X-ray Microscope (STXM) is well suited for investigating metaphase chromosome structure. The absorption cross-section of soft x-rays having energies between the carbon and oxygen K edges (284 - 531 eV) is 6 - 9.5 times greater for organic specimens than for water, which permits one to examine unstained, wet biological specimens with resolution superior to that attainable using visible light. The attenuation length of the x-rays is suitable for imaging micron thick specimens without sectioning. This large difference in cross-section yields good specimen contrast, so that fewer soft x-rays than electrons are required to image wet biological specimens at a given resolution. But most imaging techniques delivering better resolution than visible light produce radiation damage. Soft x-rays are known to be very effective in damaging biological specimens. The STXM is constructed to minimize specimen dose, but it is important to measure the actual damage induced as a function of dose in order to determine the dose range within which radiation damage does not compromise image quality.

Estimation of the noise in TEM image recorded on “imaging plate”

1987 ◽  
Vol 45 ◽  
pp. 748-749
Author(s):  
T. Oikawa ◽  
N. Mori ◽  
T. Katoh ◽  
Y. Harada ◽  
J. Miyahara ◽  
...  
Keyword(s):  
Low Dose ◽  
Quantum Noise ◽  
Laser Light ◽  
Imaging Plate ◽  
Total System ◽  
Electron Dose ◽  
X Ray ◽  
Image Recording ◽  
Recording Material ◽  
Highly Sensitive

The “Imaging Plate”(IP) is a highly sensitive image recording plate for X-ray radiography. It has been ascertained that the IP has superior properties and high practicability as an image recording material in a TEM. The sensitivity, one of the properties, is about 3 orders higher than that of conventional photo film. The IP is expected to be applied to low dose techniques. In this paper, an estimation of the quantum noise on the TEM image which appears in case of low electron dose on the IP is reported.In this experiment, the JEM-2000FX TEM and an IP having the same size as photo film were used.Figure 1 shows the schematic diagram of the total system including the TEM used in this experiment. In the reader, He-Ne laser light is scanned across the IP, then blue light is emitted from the IP.

Interfacial properties of GaSb/InAs superlattices

1993 ◽  
Vol 51 ◽  
pp. 826-827
Author(s):  
M. E. Twigg ◽  
B. R. Bennett ◽  
J. R. Waterman ◽  
J. L. Davis ◽  
B. V. Shanabrook ◽  
...  
Keyword(s):  
Gaas Substrate ◽  
Molecular Beam ◽  
Infrared Detector ◽  
Interfacial Properties ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
Absorption Coefficients ◽  
X Ray ◽  
Short Period ◽  
High Optical Absorption

Recently, the GaSb/InAs superlattice system has received renewed attention. The interest stems from a model demonstrating that short period Ga1-xInxSb/InAs superlattices will have both a band gap less than 100 meV and high optical absorption coefficients, principal requirements for infrared detector applications. Because this superlattice system contains two species of cations and anions, it is possible to prepare either InSb-like or GaAs-like interfaces. As such, the system presents a unique opportunity to examine interfacial properties.We used molecular beam epitaxy (MBE) to prepare an extensive set of GaSb/InAs superlattices grown on an GaSb buffer, which, in turn had been grown on a (100) GaAs substrate. Through appropriate shutter sequences, the interfaces were directed to assume either an InSb-like or GaAs-like character. These superlattices were then studied with a variety of ex-situ probes such as x-ray diffraction and Raman spectroscopy. These probes confirmed that, indeed, predominantly InSb-like and GaAs-like interfaces had been achieved.

Characterization of defects in tabular silver halide grains

1990 ◽  
Vol 48 (4) ◽  
pp. 1046-1047
Author(s):  
C. Goessens ◽  
D. Schryvers ◽  
J. Van Landuyt ◽  
A. Verbeeck ◽  
R. De Keyzer
Keyword(s):  
Radiation Damage ◽  
Silver Halide ◽  
Chemical Characteristics ◽  
X Ray ◽  
Free Region ◽  
Central Defect ◽  
Crystallographic Defects ◽  
Physical And Chemical ◽  
Two Sides

Silver halide grains (AgX, X=Cl,Br,I) are commonly recognized as important entities in photographic applications. Depending on the preparation specifications one can grow cubic, octahedral, tabular a.o. morphologies, each with its own physical and chemical characteristics. In the present study crystallographic defects introduced by the mixing of 5-20% iodide in a growing AgBr tabular grain are investigated. X-ray diffractometry reveals the existence of a homogeneous Ag(Br1-xIx) region, expected to be formed around the AgBr kernel. In fig. 1 a two-beam BF image, taken at T≈100 K to diminish radiation damage, of a triangular tabular grain is presented, clearly showing defect contrast fringes along four of the six directions; the remaining two sides show similar contrast under relevant diffraction conditions. The width of the central defect free region corresponds with the pure AgBr kernel grown before the mixing with I. The thickness of a given grain lies between 0.15 and 0.3 μm: as indicated in fig. 2 triangular (resp. hexagonal) grains exhibit an uneven (resp. even) number of twin interfaces (i.e., between + and - twin variants) parallel with the (111) surfaces. The thickness of the grains and the existence of the twin variants was confirmed from CTEM images of perpendicular cuts.

Elemental mass loss in silicate minerals during x-ray analysis

1990 ◽  
Vol 48 (4) ◽  
pp. 804-805
Author(s):  
P.E. Champness ◽  
R.W. Devenish
Keyword(s):  
Mass Loss ◽  
Current Density ◽  
Damage Mechanism ◽  
Beam Current ◽  
Single Chain ◽  
Plagioclase Feldspar ◽  
X Ray ◽  
Alkali Ions ◽  
Structural Order ◽  
Sheet Silicate

It has long been recognised that silicates can suffer extensive beam damage in electron-beam instruments. The predominant damage mechanism is radiolysis. For instance, damage in quartz, SiO2, results in loss of structural order without mass loss whereas feldspars (framework silicates containing Ca, Na, K) suffer loss of structural order with accompanying mass loss. In the latter case, the alkali ions, particularly Na, are found to migrate away from the area of the beam. The aim of the present study was to investigate the loss of various elements from the common silicate structures during electron irradiation at 100 kV over a range of current densities of 104 - 109 A m−2. (The current density is defined in terms of 50% of total current in the FWHM probe). The silicates so far ivestigated are:- olivine [(Mg, Fe)SiO4], a structure that has isolated Si-O tetrahedra, garnet [(Mg, Ca, Fe)3Al2Si3AO12 another silicate with isolated tetrahedra, pyroxene [-Ca(Mg, Fe)Si2O6 a single-chain silicate; mica [margarite, -Ca2Al4Si4Al4O2O(OH)4], a sheet silicate, and plagioclase feldspar [-NaCaAl3Si5O16]. Ion- thinned samples of each mineral were examined in a VG Microscopes UHV HB501 field- emission STEM. The beam current used was typically - 0.5 nA and the current density was varied by defocussing the electron probe. Energy-dispersive X-ray spectra were collected every 10 seconds for a total of 200 seconds using a Link Systems windowless detector. The thickness of the samples in the area of analysis was normally 50-150 nm.

Factors in Photographic Emulsions for Low Dose Electron Crystallography

1980 ◽  
Vol 38 ◽  
pp. 230-231
Author(s):  
T.W. Jeng ◽  
W. Chiu
Keyword(s):  
Radiation Damage ◽  
Low Dose ◽  
Damage Effect ◽  
Photographic Emulsion ◽  
Electron Crystallography ◽  
Electron Microscopic ◽  
X Ray ◽  
Signal Contrast ◽  
Diffraction Patterns ◽  
Photographic Emulsions

With the advances in preparing biological materials in a thin and highly ordered form, and in maintaining them hydrated under vacuum, electron crystallography has become an important tool for biological structure investigation at high resolution (1,2). However, the electron radiation damage would limit the capability of recording reflections with low intensities in an electron diffraction pattern. It has been demonstrated that the use of a low temperature stage can reduce the radiation damage effect and that one can expose the specimen with a higher dose in order to increase the signal contrast (3). A further improvement can be made by selecting a proper photographic emulsion. The primary factors in evaluating the suitability of photographic emulsion for recording low dose diffraction patterns are speed, fog level, electron response at low electron exposure, linearity, and usable range of exposure. We have compared these factors with three photographic emulsions including Kodak electron microscopic plate (EMP), Industrex AA x-ray film (AA x-ray) and Kodak nuclear track film (NTB3).

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