Removing interference-based effects from infrared spectra – interference fringes re-revisited

The Analyst ◽  
2020 ◽  
Vol 145 (9) ◽  
pp. 3385-3394 ◽  
Author(s):  
Thomas G. Mayerhöfer ◽  
Susanne Pahlow ◽  
Uwe Hübner ◽  
Jürgen Popp
Keyword(s):  
Refractive Index ◽  
Infrared Spectra ◽  
Band Intensity ◽  
Interference Fringes ◽  
Spectrum Interpretation

Substantial refractive index mismatches between substrate and layers lead to undulating baselines and changes of band intensity, shape and position. For proper spectrum interpretation, all of these effects must be removed.

Optic Method to Measure the Density of Gas and the Analysis on Uncertainty of Measurement

2011 ◽  
Vol 361-363 ◽  
pp. 226-231
Author(s):  
Chang Li Guo ◽  
Yan Qing Zhang
Keyword(s):  
Refractive Index ◽  
Measurement Accuracy ◽  
Uncertainty Of Measurement ◽  
Interference Theory ◽  
Interference Fringes ◽  
Air Chamber ◽  
High Measurement ◽  
Wedge Structure ◽  
High Measurement Accuracy ◽  
Optical Wedge

A optic method to measure the density of gas is put forward. That is, by using the optical Wedge structure to build air chamber and chamber for gas under test, and by measuring the differences of the optical Wedge interference fringes of the two rooms, the density of gas has been measured. The interference theory of Wedge has been theoretical analyzed, and a formula which can be used to measure the refractive index of gas is put forward, and the uncertainty of the measurement has been analyzed. The parameters of gas density, refractive index and gas thickness have been used in the formula. The results show that the method of optical Wedge interference is practical, and high measurement accuracy is achievement when the density of gas is high.

Suppression of Interference Fringes in the Infrared Spectra of Thin Polymer Films

1990 ◽  
Vol 44 (5) ◽  
pp. 901-903 ◽  
Author(s):  
P. J. Farrington ◽  
D. J. T. Hill ◽  
J. H. O'Donnell ◽  
P. J. Pomery
Keyword(s):  
Infrared Spectra ◽  
Polymer Films ◽  
Thin Polymer Films ◽  
Interference Fringes ◽  
Thin Polymer

scholarly journals AlGaN-Based Bragg Reflectors

1997 ◽  
Vol 2 ◽  
Author(s):  
O. Ambacher ◽  
M. Arzberger ◽  
D. Brunner ◽  
H. Angerer ◽  
F. Freudenberg ◽  
...  
Keyword(s):  
Refractive Index ◽  
Molecular Beam ◽  
Molar Fraction ◽  
Bragg Reflectors ◽  
Near Ultraviolet ◽  
Photothermal Deflection Spectroscopy ◽  
Interference Fringes ◽  
Measured Absorption ◽  
Ultraviolet Spectral Region ◽  
Photothermal Deflection

We have studied the dependence of the absorption edge and the refractive index of wurtzite AlxGa1−xN films on composition using transmission, ellipsometry and photothermal deflection spectroscopy. The Al molar fraction of the AlxGa1−xN films grown by plasma-induced molecular beam epitaxy was varied through the entire range of composition (0 ≤ x ≤ 1). We determined the absorption edges of AlxGa1−xN films and a bowing parameter of 1.3 ± 0.2 eV. The refractive index below the bandgap was deduced from the interference fringes, the dielectric function between 2.5 and 25 eV from ellipsometry measurements. The measured absorption coefficients and refractive indices were used to calculate the design and reflectivity of AlGaN-based Bragg reflectors working in the blue and near-ultraviolet spectral region.

Infrared Spectra of Organic Monolayers on Mica

1989 ◽  
Vol 43 (3) ◽  
pp. 473-476 ◽  
Author(s):  
George Carson ◽  
Steve Granick
Keyword(s):  
Optical Properties ◽  
Infrared Spectra ◽  
Polarized Light ◽  
Organic Monolayers ◽  
Monolayer Film ◽  
Organic Monolayer ◽  
Interference Fringes ◽  
Muscovite Mica

A method is described for obtaining infrared spectra of an organic monolayer film on muscovite mica. This task is normally difficult because mica is not metallic, and it has biaxial optical properties and produces large interference fringes when analyzed in transmission or reflection because of reflections off the front and back of a sheet. The method involves the transmission of parallel-polarized light, incident at the Brewster's angle, through a mica sheet that is oriented along one of its principal optical directions.

Optical Constants of Annealed a-Si:H from Transmittance at Normal Incidence

2001 ◽  
Vol 692 ◽  
Author(s):  
Atsutoshi Doi ◽  
Yoshiyuki Matsumoto
Keyword(s):  
Refractive Index ◽  
Network Structure ◽  
Optical Constants ◽  
Solid Phase ◽  
Refractive Index Change ◽  
Normal Incidence ◽  
Solid Phase Crystallization ◽  
Index Change ◽  
Temperature Changes ◽  
Interference Fringes

AbstractWe study changes in the optical constants of a-Si:H films caused by the thermal annealing involved in solid phase crystallization. The aim is to examine the growth mechanism, since changes in refractive index are most probably caused by a change in the network structure. The refractive index change was studied from interference fringes in transmitted light at normal incidence, and shows differing dependence on temperature in different thermal ranges. DSC measurement was also performed to examine changes in the network structure with temperature. Changes in optical and thermal properties induced by an increase of temperature reveal frequent network changes of a-Si:H below 470°C and of a-Si in the range 470 to 570°C. We also found crystallization at about 570°C, and grain growth above the crystallization temperature. Knowledge of network changes in a-Si film allows orientation control by an external seed.

Measuring Line Centers from Digitally Recorded Spectra Using a Minicomputer

1974 ◽  
Vol 28 (4) ◽  
pp. 362-368 ◽  
Author(s):  
S. C. Hurlock ◽  
J. R. Hanratty
Keyword(s):  
High Resolution ◽  
Infrared Spectra ◽  
High Accuracy ◽  
Digital Form ◽  
Measuring Line ◽  
Local Section ◽  
Standard Methods ◽  
Interference Fringes ◽  
The Difference ◽  
Very High

A system is described for determining spectral positions from high resolution infrared spectra which have been recorded in digital form on magnetic tape. The system employs a minicomputer located in the laboratory and line centers are determined by an interactive procedure in which the operator makes judgments based on information displayed on the CRT screen of the computer. This information consists of the spectrum, a reflection of a local section of the spectrum at a vertical line through the center of the screen, a plot of the difference between the spectrum and its reflection, and the square of the area under the difference curve. Very high accuracy is demonstrated for locating the centers of single lines as well as the centers of the components of incompletely resolved double lines. Determinations of spectral positions (wavenumber calibration) parallel operations that were previously performed as batch jobs by a much larger computer. Spectral positions are determined by standard methods of calibration of interference fringes and interpolation.

Three-dimensional refractive index profile of a GRIN optical waveguide using multiple beam interference fringes

2001 ◽  
Vol 191 (1-2) ◽  
pp. 39-47 ◽  
Author(s):  
N. Barakat ◽  
H.A. El-Hennawi ◽  
E.Abd. El-Ghafar ◽  
H. El-Ghandoor ◽  
R. Hassan ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Waveguide ◽  
Three Dimensional ◽  
Refractive Index Profile ◽  
Index Profile ◽  
Multiple Beam ◽  
Interference Fringes
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