Optical properties of water in the near infrared*

Palmer, Kent F.; Williams, Dudley

doi:10.1364/josa.64.001107

Cited by 649 publications

(373 citation statements)

References 8 publications

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“…2, instead of u u ¼ 400 THz, the refractive index at 509 THz (l ¼ 589 nm) was measured by a digital refractometer PAL-RI (Atago, Tokyo, Japan) and substituted into the high-frequency limit of the refractive index n ðNÞ . This is valid because the frequency dispersion of the refractive index between 400 and 509 THz is negligibly small (~0.001 for water) (61). Then, the determined complex refractive indexñðuÞ ¼ nðuÞ À ikðuÞ between 120 and 400 THz was converted into the complex dielectric constant εðuÞ via the relationshipεðuÞ ¼ñðuÞ 2 .…”

Section: Data Acquisitionmentioning

confidence: 99%

Hydrogen Bond Network of Water around Protein Investigated with Terahertz and Infrared Spectroscopy

Shiraga

Ogawa

Kondo

2016

Biophysical Journal

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The dynamical and structural properties of water at protein interfaces were characterized on the basis of the broadband complex dielectric constant (0.25 to 400 THz) of albumin aqueous solutions. Our analysis of the dielectric responses between 0.25 and 12 THz first revealed hydration water with retarded reorientational dynamics extending~8.5 Å (corresponding to three to four layers) out from the albumin surface. Second, the number of nonhydrogen-bonded water was decreased in the presence of the albumin solute, indicating protein inhibits the fragmentation of the water hydrogen-bond network. Finally, water molecules at the albumin interface were found to form a distorted hydrogen-bond structure due to topological and energetic disorder of the protein surface. In addition, the intramolecular O-H stretching vibration of water (~100 THz), which is sensitive to hydrogen-bond environment, pointed to a trend that hydration water has a larger population of strongly hydrogen-bonded water molecules compared with that of bulk water. From these experimental results, we concluded that the ''strengthened'' water hydrogen bonds at the protein interface dynamically slow down the reorientational motion of water and form the less-defective hydrogen-bond network by inhibiting the fragmentation of water-water hydrogen bonds. Nevertheless, such a strengthened water hydrogen-bond network is composed of heterogeneous hydrogen-bond distances and angles, and thus characterized as structurally ''distorted.''

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Section: Data Acquisitionmentioning

confidence: 99%

Hydrogen Bond Network of Water around Protein Investigated with Terahertz and Infrared Spectroscopy

Shiraga

Ogawa

Kondo

2016

Biophysical Journal

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“…Moreover, the dielectric properties of bacteria are assumed here to be similar to the water. This assumption is motivated by the availability of water properties in the terahertz and the infrared bands (see [14] for the range 15 THz-150 THz, [15] for the range 5 GHz-30 THz, and [16] for the range 114-833 THz). Also, this approximation has been utilized in the literature at lower frequencies and can be justified by the fact that water constitutes the majority of the cellular contents [17].…”

Section: Numerical Resultsmentioning

confidence: 99%

“…3. It is well known that water is dispersive in the terahertz and infrared bands [14][15][16]. However, it is important to emphasize that the 3D level set shape reconstruction algorithm is not limited to certain material properties as long as they are a priori known at each frequency used in the reconstruction algorithm.…”

Section: Numerical Resultsmentioning

confidence: 99%

Inverse Scattering Shape Reconstruction of 3d Bacteria Using the Level Set Algorithm

Hassan¹,

Hajihashemi²,

El-Shenawee³

2012

PIER B

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Abstract-Bacteria exist in a variety of groups of shapes, sizes, and single or multiple cell formations. In this paper, the level set shape reconstruction technique, the method of moments, and the marching cubes methods are integrated in the high frequency band for imaging three dimensional bacteria. The time step and the resolution of the marching cubes method are investigated to smooth the error function of the level set and hence speed up the convergence at high frequencies. The numerical results demonstrate the robustness of the level set algorithm for the detection of bacteria based on their shapes. The three dimensional shape reconstructions of unknown bacteria can be utilized to classify biological warfare agents.

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“…Absorption spectra for deoxyhemoglobin (Hb), oxyhemoglobin (HbO 2 ), cytochrome c oxidase (Cyt), and water (H 2 O) in the near-infrared range. The isobestic point near 800 nm is the point where the absorptivity of Hb and HbO 2 are equal (Palmer & Williams, 1974;Wray et al, 1988).…”

Section: Absorption Of Lightmentioning

confidence: 99%