scholarly journals Refractive indices of fused silica at low temperatures

1971 ◽  
Vol 75A (4) ◽  
pp. 279 ◽  
Author(s):  
R.M. Waxler ◽  
G.W. Cleek
Keyword(s):  
Low Temperatures ◽  
Fused Silica ◽  
Refractive Indices

Cerium Tetrafluoride. I. Preparation and reactions

1965 ◽  
Vol 18 (7) ◽  
pp. 959 ◽  
Author(s):  
WJ Asker ◽  
AW Wylie
Keyword(s):  
Aqueous Solution ◽  
Water Content ◽  
Water Vapour ◽  
Hydrogen Fluoride ◽  
Low Temperatures ◽  
Cerium Dioxide ◽  
Lattice Parameters ◽  
Refractive Indices ◽  
Dissociation Pressure ◽  
Cerium Trifluoride

Pure anhydrous cerium tetrafluoride is best prepared by fluorinating cerium dioxide at 350-500�. A monohydrate can be obtained from aqueous solution in a variety of ways, but it cannot be dehydrated without decomposition. It loses water "zeolitically" in vacuum, showing relatively small changes in lattice parameters for loss of 70% of its water content. Thereafter the lattice collapses, forming well-crystallized cerium trifluoride and poorly crystallized "anhydrous" cerium tetrafluoride. The refractive indices of anhydrous monoclinic cerium tetrafluoride have been measured and its fluorine dissociation pressure at 500� shown to be less than 0.5 mm. At higher temperatures the tetrafluoride sublimes incongruently, and at 835-841� it melts with extensive decomposition into a fluorine-poor liquid and a fluorine-rich vapour. Cerium tetrafluoride is easily reduced to the trifluoride by ammonia and by water vapour at low temperatures. At higher temperatures it is quantitatively converted by water vapour to cerium dioxide and hydrogen fluoride. When heated with cerium dioxide it is reduced to the trifluoride with liberation of oxygen.

scholarly journals On the refractive indices of Gaseous Potassium, Zinc, Cadmium, Mercury, Arsenic, Selenium, and Tellurium

1907 ◽  
Vol 79 (529) ◽  
pp. 202-203 ◽  
Keyword(s):  
Fused Silica ◽  
Refractive Indices ◽  
Zinc Cadmium

The present work forms a continuation of an enquiry begun by Mr. C. Cuthbertson on the refractive indices of the vapours of elements not gaseous at ordinary temperatures. The refractometer of Jamin was again employed, but tubes of fused silica were now used and other improvements introduced.

scholarly journals Refractive Index of Cadmium Sulfide Films Determined from Transmittance Measurements

2019 ◽  
Vol 3 (4) ◽  
pp. 21-29
Author(s):  
Zaheer Hussain Shah ◽  
Imtiaz Ahmad ◽  
Rabia Nasar
Keyword(s):  
Refractive Index ◽  
Cadmium Sulfide ◽  
Normal Incidence ◽  
Fused Silica ◽  
Refractive Indices ◽  
Silica Substrates

In the present work the refractive indices of thermally evaporated films of cadmium sulfide (CdS) on fused silica substrates were obtained from measurement of transmittance (T, alone) at normal incidence. Earlier, the same were determined by using measurements of reflectance (R) and transmittance (T) again at normal incidence. On comparison of the two results, we noted that the present results are in fact more, closer than those obtained earlier to the corresponding values reported for the bulk cadmium sulfide.

scholarly journals Immersion Factor of In-Water Radiance Sensors: Assessment for a Class of Radiometers

2006 ◽  
Vol 23 (2) ◽  
pp. 302-313 ◽  
Author(s):  
Giuseppe Zibordi
Keyword(s):  
Seawater Temperature ◽  
Fused Silica ◽  
Field Of View ◽  
Refractive Indices ◽  
Specific Class ◽  
Optical Components ◽  
Optical Window ◽  
Sensor Model ◽  
Half Angle ◽  
The Relationship

Abstract The spectral immersion factor of in-water radiance sensors If quantifies the effects of changes in the sensor's response when operated in water versus in air. The values of If are currently computed with a relationship derived from a basic sensor model, which only requires knowledge of the refractive indices of the water and the material constituting the sensor's optical window in contact herewith. Uncertainties in the computation of If are investigated in the 400–700-nm spectral range for a specific class of widely used multispectral radiometers. The analysis is made by comparing If values from the theoretical relationship currently in use with (i) If from a new relationship based on an extended sensor model accounting for the actual solid-angle field of view and the reflectance and transmittance of the external and internal optical components, and (ii) experimental If determined with sample radiometers having diverse optical windows made of materials with different refractive indices. Results highlight that the relationship derived from the basic sensor model introduces a 0.4% negative bias when applied to the considered class of radiometers having a fused silica optical window, a 13° in-air half-angle field of view, and an estimated detector reflectance of 0.15. Reference values of If for the specific class of radiometers, determined with the newly proposed relationship, are presented, and their dependence on seawater temperature and salinity is discussed.

scholarly journals An Experimental Study of the Formation of Talc through CaMg(CO3)2–SiO2–H2O Interaction at 100–200°C and Vapor-Saturation Pressures

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Ye Wan ◽  
Xiaolin Wang ◽  
I-Ming Chou ◽  
Wenxuan Hu ◽  
Yang Zhang ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Fused Silica ◽  
X Ray Diffraction ◽  
In Situ Raman Spectroscopy ◽  
X Ray ◽  
In Situ Raman ◽  
Geological Processes ◽  
Partial Pressures ◽  
Increasing Temperature

The metamorphic interaction between carbonate and silica-rich fluid is common in geological environments. The formation of talc from dolomite and silica-rich fluid occurs at low temperatures in the metamorphism of the CaO–MgO–SiO2–CO2–H2O system and plays important roles in the formation of economically viable talc deposits, the modification of dolomite reservoirs, and other geological processes. However, disagreement remains over the conditions of talc formation at low temperatures. In this study, in situ Raman spectroscopy, quenched scanning electron microscopy, micro-X-ray diffraction, and thermodynamic calculations were used to explore the interplay between dolomite and silica-rich fluids at relatively low temperatures in fused silica tubes. Results showed that talc formed at ≤200°C and low CO2partial pressures (PCO2). The reaction rate increased with increasing temperature and decreased with increasingPCO2. The major contributions of this study are as follows:(1)we confirmed the formation mechanism of Mg-carbonate-hosted talc deposits and proved that talc can form at ≤200°C;(2)the presence of talc in carbonate reservoirs can indicate the activity of silica-rich hydrothermal fluids; and (3) the reactivity and solubility of silica require further consideration, when a fused silica tube is used as the reactor in highP–Texperiments.

Absolute refractive indices and thermal coefficients of fused silica and calcium fluoride near 193 nm

1998 ◽  
Vol 37 (25) ◽  
pp. 5964 ◽  
Author(s):  
Rajeev Gupta ◽  
John H. Burnett ◽  
Ulf Griesmann ◽  
Matthew Walhout
Keyword(s):  
Calcium Fluoride ◽  
Fused Silica ◽  
Refractive Indices ◽  
193 Nm

scholarly journals On the refractive indices of mercury and thallium vapours

1921 ◽  
Vol 100 (703) ◽  
pp. 191-200 ◽  
Keyword(s):  
Parallel Plate ◽  
Michelson Interferometer ◽  
Fused Silica ◽  
Refractive Indices ◽  
Melting Points ◽  
Plane Parallel Plate ◽  
Zinc Cadmium ◽  
Other Substances ◽  
Cadmium Selenium ◽  
Sodium Vapour

Although numerous accurate and extended determinations have been made of the refractive indices of gases which exist as such at ordinary temperatures, few have been made with the vapours of elements or compounds which, at room temperatures, are solids and possess a low equilibrium vapour pressure in that state. Notable among the latter are the determinations made by Prof. R. W. Wood with sodium vapour and those made by Messrs. C. Cuthbertson and E. Parr Metcalfe with the vapours of sulphur, phosphorus, mercury, zinc, cadmium, selenium, and tellurium. In the work of both of these investigations an interference method was adopted. In Wood’s a Michelson interferometer was used and in Cuthbertson and Metcalfe’s one of the Jamin type. For the investigation of Cuthbertson and Metcalfe the glass interferometer tubes ordinarily used with Jamin interferometers were wholly unsuitable. These, as is well known, are provided with plane parallel plate glass ends ground in and luted with shellac or a wax having similar properties, and when heated to 300°C. or higher, the shellac chars and the tubes frequently crack, soften or become distorted. For these reasons Cuthbertson and Metcalfe had recourse to interferometer tubes made of fused silica which were made, with great skill, by Messrs. Heraeus, of Hanau. The ends of the tubes through which the interfering rays passed were plates of quartz ground optically flat, fused into the tubes and again polished. In their manufacture such tubes are, however, difficult to make. Failures are frequent and consequently the tubes are expensive. On this account investigators have been deterred hitherto from studying the refractivities of the vapours of metals and other substances, having moderately high melting points and vapourising temperatures.

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