Fourier Transform-Plasmon Waveguide Spectroscopy: A Nondestructive Multifrequency Method for Simultaneously Determining Polymer Thickness and Apparent Index of Refraction

Germanium- and carbon-based films were deposited by plasma-enhanced chemical vapor deposition from tetramethylgermane (TMGe) with additions of oxygen, hydrogen, or argon. The index of refraction, extinction coefficient, and optical gap and Fourier transform infrared spectra of the films were measured as well as their stability in regular ambiance. It was found that the films deposited from pure TMGe were stable in time only if deposited at a negative bias above −250 V direct current. Films deposited at a bias of −150 V direct current could be stabilized by significant additions of oxygen to the plasma and complete stabilization was achieved at O2/TMGe ratios larger than 3 in the gas feed when GeOx films containing small amounts of C and H were obtained. Additions of hydrogen or argon to TMGe had only slight effects in improving the stability off the films.

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Comparison of Calculated and Recorded Electron Energy-Loss Spectra of Aluminium and Carbon

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100133916 ◽

1990 ◽

Vol 48 (2) ◽

pp. 64-65

Author(s):

L. Reimer ◽

R. Oelgeklaus

Keyword(s):

Fourier Transform ◽

Energy Loss ◽

Electron Energy ◽

Rotational Symmetry ◽

Mean Free Path ◽

Single Scattering ◽

Specimen Thickness ◽

Two Dimensional ◽

Image Position ◽

Electron Energy Loss

Quantitative electron energy-loss spectroscopy (EELS) needs a correction for the limited collection aperture α and a deconvolution of recorded spectra for eliminating the influence of multiple inelastic scattering. Reversely, it is of interest to calculate the influence of multiple scattering on EELS. The distribution f(w,θ,z) of scattered electrons as a function of energy loss w, scattering angle θ and reduced specimen thickness z=t/Λ (Λ=total mean-free-path) can either be recorded by angular-resolved EELS or calculated by a convolution of a normalized single-scattering function ϕ(w,θ). For rotational symmetry in angle (amorphous or polycrystalline specimens) this can be realised by the following sequence of operations :(1)where the two-dimensional distribution in angle is reduced to a one-dimensional function by a projection P, T is a two-dimensional Fourier transform in angle θ and energy loss w and the exponent -1 indicates a deprojection and inverse Fourier transform, respectively.

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FR-IR Molecular Microanalysis System

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100134958 ◽

1990 ◽

Vol 48 (2) ◽

pp. 270-271

Author(s):

John A. Reffner ◽

William T. Wihlborg

Keyword(s):

Fourier Transform ◽

Fourier Transform Infrared ◽

Integrated System ◽

Morphological Examination ◽

Fully Integrated ◽

Ir Microscopy ◽

Normal Functions ◽

Infrared Microspectroscopy ◽

Infrared Spectral ◽

Ft Ir

The IRμs™ is the first fully integrated system for Fourier transform infrared (FT-IR) microscopy. FT-IR microscopy combines light microscopy for morphological examination with infrared spectroscopy for chemical identification of microscopic samples or domains. Because the IRμs system is a new tool for molecular microanalysis, its optical, mechanical and system design are described to illustrate the state of development of molecular microanalysis. Applications of infrared microspectroscopy are reviewed by Messerschmidt and Harthcock.Infrared spectral analysis of microscopic samples is not a new idea, it dates back to 1949, with the first commercial instrument being offered by Perkin-Elmer Co. Inc. in 1953. These early efforts showed promise but failed the test of practically. It was not until the advances in computer science were applied did infrared microspectroscopy emerge as a useful technique. Microscopes designed as accessories for Fourier transform infrared spectrometers have been commercially available since 1983. These accessory microscopes provide the best means for analytical spectroscopists to analyze microscopic samples, while not interfering with the FT-IR spectrometer’s normal functions.

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Interferometric (Fourier-Spectroscopic) Measurement of Electron Energy Distributions

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100134144 ◽

1990 ◽

Vol 48 (2) ◽

pp. 110-111 ◽

Cited By ~ 1

Author(s):

F. Hasselbach ◽

A. Schäfer

Keyword(s):

Group Velocity ◽

Wave Packets ◽

Index Of Refraction ◽

Electron Wave ◽

Fringe Contrast ◽

Faraday Cage ◽

Optical Index ◽

Wien Filter ◽

Coherent Wave ◽

Electric And Magnetic Fields

Möllenstedt and Wohland proposed in 1980 two methods for measuring the coherence lengths of electron wave packets interferometrically by observing interference fringe contrast in dependence on the longitudinal shift of the wave packets. In both cases an electron beam is split by an electron optical biprism into two coherent wave packets, and subsequently both packets travel part of their way to the interference plane in regions of different electric potential, either in a Faraday cage (Fig. 1a) or in a Wien filter (crossed electric and magnetic fields, Fig. 1b). In the Faraday cage the phase and group velocity of the upper beam (Fig.1a) is retarded or accelerated according to the cage potential. In the Wien filter the group velocity of both beams varies with its excitation while the phase velocity remains unchanged. The phase of the electron wave is not affected at all in the compensated state of the Wien filter since the electron optical index of refraction in this state equals 1 inside and outside of the Wien filter.

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TEM characterization of proton-exchanged LiNbO3 optical waveguides

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010014395x ◽

1986 ◽

Vol 44 ◽

pp. 480-481

Author(s):

W. E. Lee

Keyword(s):

Refractive Index ◽

Benzoic Acid ◽

Optical Waveguides ◽

Total Internal Reflection ◽

Index Of Refraction ◽

Optical Measurements ◽

Lithium Ions ◽

Wide Channel ◽

Tem Characterization

An optical waveguide consists of a several-micron wide channel with a slightly different index of refraction than the host substrate; light can be trapped in the channel by total internal reflection.Optical waveguides can be formed from single-crystal LiNbO3 using the proton exhange technique. In this technique, polished specimens are masked with polycrystal1ine chromium in such a way as to leave 3-13 μm wide channels. These are held in benzoic acid at 249°C for 5 minutes allowing protons to exchange for lithium ions within the channels causing an increase in the refractive index of the channel and creating the waveguide. Unfortunately, optical measurements often reveal a loss in waveguiding ability up to several weeks after exchange.

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The extended Fourier algorithm: Application in discrete optics and electron holography

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100172322 ◽

1994 ◽

Vol 52 ◽

pp. 918-919

Author(s):

E. Voelkl ◽

L. F. Allard

Keyword(s):

Fourier Transform ◽

Fourier Transforms ◽

Sampling Rate ◽

Electron Holography ◽

Optical Bench ◽

Fourier Space ◽

Ccd Cameras ◽

Simulated Image ◽

Initial Sampling ◽

Fourier Algorithm

The conventional discrete Fourier transform can be extended to a discrete Extended Fourier transform (EFT). The EFT allows to work with discrete data in close analogy to the optical bench, where continuous data are processed. The EFT includes a capability to increase or decrease the resolution in Fourier space (thus the argument that CCD cameras with a higher number of pixels to increase the resolution in Fourier space is no longer valid). Fourier transforms may also be shifted with arbitrary increments, which is important in electron holography. Still, the analogy between the optical bench and discrete optics on a computer is limited by the Nyquist limit. In this abstract we discuss the capability with the EFT to change the initial sampling rate si of a recorded or simulated image to any other(final) sampling rate sf.

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Microspectroscopy Using a Solid Immersion Lens

Microscopy and Microanalysis ◽

10.1017/s1431927600026817 ◽

2001 ◽

Vol 7 (S2) ◽

pp. 148-149

Author(s):

C.D. Poweleit ◽

J Menéndez

Keyword(s):

Spatial Resolution ◽

Focal Plane ◽

Numerical Aperture ◽

Normal Incidence ◽

Spot Size ◽

Index Of Refraction ◽

Objective Lens ◽

Improvement Factor ◽

Oil Immersion ◽

Long Time

Oil immersion lenses have been used in optical microscopy for a long time. The light’s wavelength is decreased by the oil’s index of refraction n and this reduces the minimum spot size. Additionally, the oil medium allows a larger collection angle, thereby increasing the numerical aperture. The SIL is based on the same principle, but offers more flexibility because the higher index material is solid. in particular, SILs can be deployed in cryogenic environments. Using a hemispherical glass the spatial resolution is improved by a factor n with respect to the resolution obtained with the microscope’s objective lens alone. The improvement factor is equal to n2 for truncated spheres.As shown in Fig. 1, the hemisphere SIL is in contact with the sample and does not affect the position of the focal plane. The focused rays from the objective strike the lens at normal incidence, so that no refraction takes place.

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