Optical Propagation in Water

2006 ◽  
Author(s):  
Michael E. Thomas
Keyword(s):  
Optical Properties ◽  
Pure Water ◽  
Far Infrared ◽  
Band Edge ◽  
Debye Relaxation ◽  
Microwave Frequencies ◽  
Optical Propagation ◽  
Microscopic Field ◽  
Basic Physics ◽  
Vibrational Bands

From a basic physics perspective, liquids are the least understood state of matter. Yet this medium plays an important role in the process of life on this planet. The human body is largely composed of liquids, and three-quarters of the surface of the earth is covered by seawater. The main liquid of interest in this chapter, and to the applied scientist and engineer, is water. The importance of understanding the optical properties of water cannot be overemphasized. The chapter appropriately begins with a discussion of the optical properties of pure water, since it is the main ingredient in seawater and in biomedical fluids. Pure water is an insulator with a strong dipole moment and an effective electronic band edge in the ultraviolet near 0.16 μm (62,500 cm−1). Absorption near the band edge shows similar structure to that observed in solids. Water has extensive infrared vibrational bands just as in the gas phase. Dipoles in a liquid can partially rotate in response to the polarization of the incident microscopic field, and Debye relaxation bands occur in the microwave region. A permittivity model for Debye relaxation was presented in Chapter 4 by Eq. 4.60. This is an important mechanism that describes the optical properties of liquids at far-infrared and microwave frequencies.

Molekülinterne Dipolorientierung und dielektrische Absorption in verdünnter Lösung bei Mikro- und Submillimeterwellen. III. Methyläther

1985 ◽  
Vol 40 (12) ◽  
pp. 1206-1219
Author(s):  
Gerhard Klages
Keyword(s):  
Dielectric Loss ◽  
Relaxation Times ◽  
Far Infrared ◽  
Infrared Region ◽  
Debye Relaxation ◽  
Microwave Frequencies ◽  
Rotational Oscillation ◽  
Zero Correlation ◽  
Wave Numbers ◽  
Aliphatic Ethers

The dielectric loss of seven aromatic ethers (anisole, 1,2- and 1.4-dimethoxybenzene, 4-methylanisole, 4-chloranisole, 1- and 2-naphtholmethylether) and of three aliphatic ethers has been measured at 20 °C in very dilute solutions of aliphatic solvents (n-heptene, cyclohexene and decalin). The microwave frequencies used cover 2 to 70 GHz, in the far infrared region (FIR), wave numbers 40 to 300 cm-1 have been available. All microwave spectra of loss factor ε´´ are analysed in terms of two or three absorption areas by fitting dispersion steps and Debye relaxation times and employing non-zero correlation times of angular momentum. On the other hand, Lorentz curves are fitted to the FIR absorption spectra of α (ν̄). The dispersion step got from the dielectric loss spectra now measured includes all orientation processes of the permanent molecular dipole, and it agrees with the value obtained by the so called optical method. There are about 10% of the step which belong to the FIR absorption. In aromatic ethers the methoxy group is partly hindered to rotate, in the naphthol compounds to even a higher degree. This fact is discussed concerning mesomerism and steric hindrance. All studied methyl ethers show a characteristic resonance near 100 cm-1, which is suggested to be due to a rotational oscillation of the group.

scholarly journals Broadband spectroscopy of astrophysical ice analogues

2019 ◽  
Vol 629 ◽  
pp. A112 ◽  
Author(s):  
B. M. Giuliano ◽  
A. A. Gavdush ◽  
B. Müller ◽  
K. I. Zaytsev ◽  
T. Grassi ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Time Domain ◽  
Complex Refractive Index ◽  
Far Infrared ◽  
Infrared Region ◽  
Thz Radiation ◽  
The Real ◽  
Thz Range ◽  
The Time Domain

Context. Reliable, directly measured optical properties of astrophysical ice analogues in the infrared and terahertz (THz) range are missing from the literature. These parameters are of great importance to model the dust continuum radiative transfer in dense and cold regions, where thick ice mantles are present, and are necessary for the interpretation of future observations planned in the far-infrared region. Aims. Coherent THz radiation allows for direct measurement of the complex dielectric function (refractive index) of astrophysically relevant ice species in the THz range. Methods. We recorded the time-domain waveforms and the frequency-domain spectra of reference samples of CO ice, deposited at a temperature of 28.5 K and annealed to 33 K at different thicknesses. We developed a new algorithm to reconstruct the real and imaginary parts of the refractive index from the time-domain THz data. Results. The complex refractive index in the wavelength range 1 mm–150 μm (0.3–2.0 THz) was determined for the studied ice samples, and this index was compared with available data found in the literature. Conclusions. The developed algorithm of reconstructing the real and imaginary parts of the refractive index from the time-domain THz data enables us, for the first time, to determine the optical properties of astrophysical ice analogues without using the Kramers–Kronig relations. The obtained data provide a benchmark to interpret the observational data from current ground-based facilities as well as future space telescope missions, and we used these data to estimate the opacities of the dust grains in presence of CO ice mantles.

Far Infrared Optical Properties of Amorphous As–Se System

1982 ◽  
Vol 21 (Part 1, No. 3) ◽  
pp. 418-423 ◽  
Author(s):  
Seinosuke Onari ◽  
Osamu Sugino ◽  
Michio Kato ◽  
Toshihiro Arai
Keyword(s):  
Optical Properties ◽  
Far Infrared ◽  
Infrared Optical Properties

Optical Properties by Far Infrared Ellipsometry

1968 ◽  
Vol 115 (1) ◽  
pp. 106 ◽  
Author(s):  
Charlie E. Jones ◽  
A. Ray Hilton
Keyword(s):  
Optical Properties ◽  
Far Infrared ◽  
Infrared Ellipsometry

The Effects of Composition on the Spectral Loss Characteristics of SiGe Planar Waveguide Structures

1992 ◽  
Vol 281 ◽  
Author(s):  
Yang Zuoya ◽  
B. L. Weiss ◽  
G. Shao ◽  
F. Namavar
Keyword(s):  
Optical Properties ◽  
Planar Waveguide ◽  
Waveguide Structure ◽  
Propagation Loss ◽  
Band Edge ◽  
Optical Confinement ◽  
Structural And Optical Properties ◽  
Edge Absorption

ABSTRACTThe effect of the Si:Ge ratio in SiGe/Si heterostructures on the structural and optical properties of SiGe/Si planar waveguide are reported here for Ge concentrations from 1 to 33.6%. The high propagation loss at 1.15 pm is due to band edge absorption, which increases as the Ge concentration increases, while the loss at longer wavelengths (1.523 pm) increases with decreasing Si concentration, due to the reduced optical confinement of the waveguide structure.

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