Digital Recording of Mass Spectra in Geologic Studies. II

1972 ◽  
Vol 9 (7) ◽  
pp. 824-834 ◽  
Author(s):  
J. S. Stacey ◽  
E. E. Wilson ◽  
R. Terrazas
Keyword(s):  
Digital Data ◽  
National Bureau ◽  
Mass Spectrometers ◽  
Mass Unit ◽  
Programming Techniques ◽  
Recorded Data ◽  
System Bias ◽  
Vibrating Reed ◽  
Feedback Resistor ◽  
Data Calibration

The digital system described herein can record data from several mass spectrometers on a single magnetic tape. Programs have been written for isotopic abundance calculations of lead, thorium, uranium, strontium, and argon analyses. The programming techniques successfully recognize and reject spurious data. Both chart and digitally recorded data are presented for seven analyses of the U.S. National Bureau of Standards common lead standard SRM 981. Standard deviations of the ratios of the digital data range from 0.018% for the 207Pb/206Pb to 0.038% for the 208Pb/204Pb. The equivalent hand-processed values are 0.044 and 0.066%, respectively. The measured ratios are offset from their absolute values almost entirely by a fractionation component of about 0.16% per mass unit. Other bias introduced by the system is shown to be very small and probably not greater than 0.01% for the digital data and 0.05% for chart-read data. Calibration of the vibrating reed electrometer amplifier with current flowing through the feedback resistor has considerably improved the analytical precision and reduced the system bias.

scholarly journals The newly developed airborne radio-echo sounding system of the AWI as a glaciological tool

1999 ◽  
Vol 29 ◽  
pp. 231-238 ◽  
Author(s):  
U. Nixdorf ◽  
D. Steinhage ◽  
U. Meyer ◽  
L. Hempel ◽  
M. Jenett ◽  
...  
Keyword(s):  
Digital Data ◽  
Radar Signal ◽  
Ice Shelves ◽  
System Sensitivity ◽  
Ice Caps ◽  
Radio Echo Sounding ◽  
Recorded Data ◽  
Along Track ◽  
Echo Sounding

AbstractSince 1994 the Alfred Wegener Institute (AWI) has operated an airborne radio-echo sounding system for remote-sensing studies of the polar ice caps in Antarctica and in Greenland. It is used to map ice thicknesses and internal layernigs of glaciers, ice sheets and ice shelves, and is capable of penetrating ice thicknesses of up to 4 km. The system was designed and built by AWI in cooperation with Aerodata Flugmeßtechnik GmbH, Technische Umversitat Hamburg-Harburg and the Deutsches Zentrum fur Luft- und Raumfahrt e.V. The system uses state-of-the-art techniques, and results in high vertical (5 m) as well as along-track (3.25 m) resolution. The radar signal is a 150 MHz burst with a duration of 60 or 600 ns. The peak power is 1.6 kW, and the system sensitivity is 190 dB. The short backfire principle has been adopted and optimized for antennae used on Polar2, a Dormer 228-100 aircraft, resulting in an antenna gain of 14 dB each. Digital data recording allows further processing. The quality of the recorded data can be monitored on screen and as online analogue plots during the flight.

Computerized Treatment of Ultraviolet and Visible Absorption Spectra

1974 ◽  
Vol 28 (1) ◽  
pp. 52-60 ◽  
Author(s):  
Herbert Känzig ◽  
Regula Lorenz ◽  
Urs P. Wild
Keyword(s):  
Absorption Spectra ◽  
Digital Data ◽  
Calibration Data ◽  
Visible Absorption ◽  
Large Computer ◽  
Data Smoothing ◽  
Double Beam ◽  
Recorded Data ◽  
Computerized Treatment ◽  
Reduced Data

A versatile double beam ultraviolet and visible spectrophotometer, which uses a small digital computer to collect optical absorption spectra, has been developed in our laboratories. Digital data are stored on paper tape. This work describes the subsequent data treatment on a large computer. Subroutines for wavelength calibration, data smoothing, and data presentation have been written. Spectra obtained in different or overlapping regions with various concentrations may be combined to a single plot of molar absorption coefficients. The data analysis is based on statistical concepts. The standard deviation of the reduced data is calculated and also plotted. This represents a measure of the precision of the recorded data, information which is not easily obtained from commercial spectrometers. Details of the software system with examples of its performance are also presented.

Trial production of γ-type energy filtering TEM

1995 ◽  
Vol 53 ◽  
pp. 604-605
Author(s):  
Y. Taniguchi ◽  
E. Nakazawa ◽  
S. Taya
Keyword(s):  
Magnetic Energy ◽  
Electron Optics ◽  
Electron Microscopic ◽  
Mass Spectrometers ◽  
Ion Optics ◽  
Energy Filtering ◽  
New Information ◽  
New Type ◽  
Fringing Fields

Imaging energy filters can add new information to electron microscopic images with respect to energy-axis, so-called electron spectroscopic imaging (ESI). Recently, many good results have been reported using this imaging technique. ESI also allows high-contrast observation of unstained biological samples, becoming a trend of the field of morphology. We manufactured a new type of energy filter as a trial production. This energy filter consists of two magnets, and we call γ-filter since the trajectory of electrons shows ‘γ’-shape inside the filter. We evaluated the new energyγ-filter TEM with the γ-filter.Figure 1 shows schematic view of the electron optics of the γ-type energy filter. For the determination of the electron-optics of the γ-type energy filter, we used the TRIO (Third Order Ion Optics) program which has been developed for the design of high resolution mass spectrometers. The TRIO takes the extended fringing fields (EFF) into consideration. EFF makes it difficult to design magnetic energy filters with magnetic sector fields.

Practical applications of scanning tunneling microscopy

1989 ◽  
Vol 47 ◽  
pp. 18-19
Author(s):  
D. R. Denley
Keyword(s):  
High Resolution ◽  
Scanning Tunneling Microscopy ◽  
Quantitative Information ◽  
Digital Data ◽  
Scanning Tunneling ◽  
Ambient Atmosphere ◽  
Tunneling Microscopy ◽  
Clear Trend ◽  
Practical Applications ◽  
Promising Tool

Scanning tunneling microscopy (STM) has recently been introduced as a promising tool for analyzing surface atomic structure. We have used STM for its extremely high resolution (especially the direction normal to surfaces) and its ability for imaging in ambient atmosphere. We have examined surfaces of metals, semiconductors, and molecules deposited on these materials to achieve atomic resolution in favorable cases.When the high resolution capability is coupled with digital data acquisition, it is simple to get quantitative information on surface texture. This is illustrated for the measurement of surface roughness of evaporated gold films as a function of deposition temperature and annealing time in Figure 1. These results show a clear trend for which the roughness, as well as the experimental deviance of the roughness is found to be minimal for evaporation at 300°C. It is also possible to contrast different measures of roughness.

Convergent-beam thickness determination: The advantages of digital imaging

1994 ◽  
Vol 52 ◽  
pp. 420-421
Author(s):  
Stuart McKernan ◽  
C. Barry Carter
Keyword(s):  
Intensity Variation ◽  
Convergent Beam Electron Diffraction ◽  
Digital Data ◽  
Thickness Determination ◽  
Frequent Use ◽  
Automated Processing ◽  
Beam Thickness ◽  
Convergent Beam ◽  
Remarkable Agreement

Convergent-beam electron diffraction (CBED) patterns contain an immense amount of information relating to the structure of the material from which they are obtained. The analysis of these patterns has progressed to the point that under appropriate, well specified conditions, the intensity variation within the CBED discs may be understood in a quantitative sense. Rossouw et al for example, have produced numerical simulations of zone-axis CBED patterns which show remarkable agreement with experimental patterns. Spence and co-workers have obtained the structure factor parameters for lowindex reflections using the intensity variation in 2-beam CBED patterns. Both of these examples involve the use of digital data. Perhaps the most frequent use for quantitative CBED analysis is the thickness determination described by Kelly et al. This analysis has been implemented in a variety of different ways; from real-time, in-situ analysis using the microscope controls, to measurements of photographic prints with a ruler, to automated processing of digitally acquired images. The potential advantages of this latter process will be presented.

Slow-scan CCD cameras and low-dose High-Resolution Electron Microscopy: Direct and quantitative

1994 ◽  
Vol 52 ◽  
pp. 412-413
Author(s):  
M. Pan
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Structural Damage ◽  
Low Dose ◽  
Dynamic Range ◽  
High Resolution Electron Microscopy ◽  
Operating Conditions ◽  
Digital Data ◽  
Ccd Cameras ◽  
Resolution Electron

It has been known for many years that materials such as zeolites, polymers, and biological specimens have crystalline structures that are vulnerable to electron beam irradiation. This radiation damage severely restrains the use of high resolution electron microscopy (HREM). As a result, structural characterization of these materials using HREM techniques becomes difficult and challenging. The emergence of slow-scan CCD cameras in recent years has made it possible to record high resolution (∽2Å) structural images with low beam intensity before any apparent structural damage occurs. Among the many ideal properties of slow-scan CCD cameras, the low readout noise and digital recording allow for low-dose HREM to be carried out in an efficient and quantitative way. For example, the image quality (or resolution) can be readily evaluated on-line at the microscope and this information can then be used to optimize the operating conditions, thus ensuring that high quality images are recorded. Since slow-scan CCD cameras output (undistorted) digital data within the large dynamic range (103-104), they are ideal for quantitative electron diffraction and microscopy.

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