On: “Thin‐layer response and spectral bandwidth” by N. de Voogd and H. den Rooijen (GEOPHYSICS, 48, 12–18).

Geophysics ◽  
1985 ◽  
Vol 50 (1) ◽  
pp. 167-167
Author(s):  
J. G. Saha
Keyword(s):  
Thin Layer ◽  
Scaling Factor ◽  
Spectral Bandwidth ◽  
Frequency Scaling ◽  
Zero Phase ◽  
Frequency Axis

In their paper de Voogd and den Rooijen investigated the effects of spectral bandwidths of zero‐phase signals on interface resolution and also the response of a thin layer when the bandwidth is inadequate. They suggested a type of wavelet manipulation in modeling experiments by a simple frequency scaling and a shift [equation (19)] [Formula: see text] where p is the scaling factor and s is the shift along the frequency axis. The increase in spectral bandwidth which results from this transformation was also derived by the authors in equation (20).

Thin‐layer response and spectral bandwidth

Geophysics ◽  
1983 ◽  
Vol 48 (1) ◽  
pp. 12-18 ◽  
Author(s):  
N. de Voogd ◽  
H. den Rooijen
Keyword(s):  
Thin Layer ◽  
Time Derivative ◽  
Spectral Bandwidth ◽  
Thickness Estimation ◽  
Zero Phase

A derivation is presented of the response of an embedded thin layer to a vertically incident seismic pulse. The reflected pulse has the shape of the time derivative of the incident‐wavelet, and its amplitude is proportional to the two‐way traveltime in the thin layer and to a factor depending upon the ratio of acoustic impedances. The influence of spectral bandwidth on interface resolution and thin‐layer response is investigated by means of zero‐phase signals, and a filtering philosophy is proposed which enables thickness estimation either from amplitude or from peak‐to‐trough time.

Thin-layer ultraviolet–visible reflectance spectroelectrochemistry with a spinning-grating monochromator

1990 ◽  
Vol 68 (12) ◽  
pp. 2234-2238 ◽  
Author(s):  
David H. Jones ◽  
A. Scott Hinman
Keyword(s):  
Time Delay ◽  
Thin Layer ◽  
Noise Level ◽  
Point Spectrum ◽  
Spectral Bandwidth ◽  
Grating Monochromator ◽  
Uv Visible ◽  
Scanning Spectroscopy ◽  
Visible Reflectance ◽  
Rapid Scanning

A thin-layer UV–visible spectroelectrochemistry system has been constructed using a commercially available spinning-grating monochromator. The spectroelectrochemical experiment is capable of scanning a wavelength range of 369 to 617 nm in 2.1 ms. The time delay between successive scans is 83 ms. The maximum peak-to-peak noise level in a 300-point spectrum collected during 2.1 ms with a spectral bandwidth of 2 nm is 0.03 absorbance units. The anodic spectroelectrochemistry of tetraphenylporphinatocopper(II), studied using the system, is presented. Keywords: thin-layer spectroelectrochemistry, rapid-scanning spectroscopy, spinning-grating monochromator, tetraphenylporphinatocopper(II).

Applications of Photoelectron Microscopy

1976 ◽  
Vol 34 ◽  
pp. 506-507
Author(s):  
William J. Baxter
Keyword(s):  
Electron Microscopy ◽  
Thermal Decomposition ◽  
Chemical Composition ◽  
Ultraviolet Radiation ◽  
Thin Layer ◽  
Edge Effects ◽  
Electron Optics ◽  
Surface Layers ◽  
Crystalline Orientation ◽  
Fluorescent Screen

In this form of electron microscopy, photoelectrons emitted from a metal by ultraviolet radiation are accelerated and imaged onto a fluorescent screen by conventional electron optics. image contrast is determined by spatial variations in the intensity of the photoemission. The dominant source of contrast is due to changes in the photoelectric work function, between surfaces of different crystalline orientation, or different chemical composition. Topographical variations produce a relatively weak contrast due to shadowing and edge effects.Since the photoelectrons originate from the surface layers (e.g. ∼5-10 nm for metals), photoelectron microscopy is surface sensitive. Thus to see the microstructure of a metal the thin layer (∼3 nm) of surface oxide must be removed, either by ion bombardment or by thermal decomposition in the vacuum of the microscope.

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