Optical Cell for the Observation of Raman Scattering in Gases at High Pressures

1960 ◽  
Vol 31 (4) ◽  
pp. 414-415 ◽  
Author(s):  
J. C. Stryland ◽  
A. D. May
Keyword(s):  
Raman Scattering ◽  
High Pressures ◽  
Optical Cell

α-Glycine under high pressures: a Raman scattering study

2003 ◽  
Vol 339 (1) ◽  
pp. 23-30 ◽  
Author(s):  
Chitra Murli ◽  
Surinder M. Sharma ◽  
S. Karmakar ◽  
S.K. Sikka
Keyword(s):  
Raman Scattering ◽  
High Pressures ◽  
Scattering Study

scholarly journals Experimental Investigation of Droplet Injections in the Vicinity of the Critical Point: A comparison of different model approaches

2017 ◽  
Author(s):  
Christoph Steinhausen ◽  
Grazia Lamanna ◽  
Bernhard Weigand ◽  
Rolf Stierle ◽  
Joachim Groß ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Raman Scattering ◽  
High Pressures ◽  
Region Of Interest ◽  
Theoretical Models ◽  
Nitrogen Atmosphere ◽  
Material Surface ◽  
Atmospheric Conditions ◽  
Mixing Processes ◽  
Two Phase

The disintegration process of liquid fuel within combustion chambers is one of the most important parameters forefficient and stable combustion. Especially for high pressures exceeding the critical value of the injected fluids the mixing processes are not fully understood yet. Recently, different theoretical macroscopic models have been introduced to understand breakdown of the classical two phase regime and predict the transition from evaporation to a diffuse-mixing process. In order to gain deeper insight into the physical processes of this transition, a parametric study of free-falling n-pentane droplets in an inert nitrogen atmosphere is presented. Atmospheric conditions varied systematically from sub- to supercritical values with respect to the fluid properties. An overlay of a diffuse lighted image with a shadowgram directly in the optical setup (front lighted shadowgraphy) was applied to simultaneously detect the presence of a material surface of the droplet as well as changes in density gradients in the surrounding atmosphere. The experimental investigation illustrates, that the presence of a material surface cannot be shown by a direct shadowgram. However, reflections and refractions caused by diffuse ambient illumination are able to indicate the presence of a material surface. In case of the supercritical droplet injections in this study, front lighted shadowgraphy clearly revealed the presence of a material surface, even when the pre-heated droplets are released into a supercritical atmosphere. This detection of the droplet interface indicates, that the droplet remains subcritical in the region of interest, even though it is injected into a supercritical atmosphere. Based on the adiabatic mixing assumption recent Raman-scattering results in the wake of the droplet are re-evaluated to compute the temperature distribution. Presented experimental findings as well as the re-evaluation of recent Raman scattering results are compared to thermodynamic models to predict the onset of diffuse-mixing and supercritical disintegration of the droplet. Additionally, a one dimensional evaporation model is used to evaluate the validity of the adiabatic mixing assumption in the estimation of the droplet temperature. The presented findings contribute to the understanding of recent theoretical models for prediction of spray and droplet disintegration and the onset of diffuse-mixing processes.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4635

Solid-phase polymerizations at high pressures

1970 ◽  
Vol 23 (3) ◽  
pp. 511 ◽  
Author(s):  
MG Bradbury ◽  
SD Hamann ◽  
M Linton
Keyword(s):  
High Pressure ◽  
Spectral Analysis ◽  
Solid State ◽  
High Pressures ◽  
Solid Phase ◽  
Crystal Form ◽  
Optical Cell ◽  
Itaconic Anhydride ◽  
Temperature Requirements ◽  
Infrared Spectral

The following compounds have been found to polymerize spontaneously in the solid state at pressures in the range 10-50 kbar, at temperatures between 20 and 200�C: acrylamide, p-phenylstyrene, potassium p-styrenesulphonate, itaconic anhydride, maleic anhydride, maleimide, 1,2,3,6-tetrahydrophthalic acid, 1,2,3,6-tetrahydrophthalic anhydride, acenaphthylene, p-benzoquinone, N,N'-p-phenylene-dimaleimide, sulpholene, diphenylacetylene, 8-trioxan. The pressure-temperature requirements for polymerization have been determined in a high-pressure "squeezer" apparatus and in a diamond optical cell which permits infrared spectral analysis of a specimen while it is under compression. Apart from diphenylacetylene and trioxan, the compounds that polymerized were either monosubstituted ethylenes or cyclic 1,2-disubstituted ethylenes. Non-cyclic 1,2-disubstituted ethylenes and tri-substituted and tetra-substituted ethylenes failed to polymerize. There is evidence that shearing stresses played a part in some of the reactions. 1-Allyl-2-thiourea did not polymerize, but transformed from its stable crystal form I to the unstable modification 11.

Raman scattering of vibrational overtones in deuterium at high pressures

1992 ◽  
Vol 89 (3-4) ◽  
pp. 707-710 ◽  
Author(s):  
Jon H. Eggert ◽  
Chang-sheng Zha ◽  
Russell J. Hemley ◽  
Ho-kwang Mao
Keyword(s):  
Raman Scattering ◽  
High Pressures ◽  
Vibrational Overtones

Spin-gap mode in the charge-ordered phase ofNaV2O5studied by Raman scattering under high pressures

2010 ◽  
Vol 81 (5) ◽  
Author(s):  
Yoshiko Tanokura ◽  
Takayuki Morita ◽  
Shuhei Ishima ◽  
Shunsuke Ikeda ◽  
Haruhiko Kuroe ◽  
...  
Keyword(s):  
Raman Scattering ◽  
High Pressures ◽  
Spin Gap ◽  
Gap Mode

Raman scattering studies on mercuric iodide at high pressures and at low temperatures

2005 ◽  
Vol 369 (1-4) ◽  
pp. 287-292
Author(s):  
S. Karmakar ◽  
S.K. Deb ◽  
Surinder M. Sharma
Keyword(s):  
Raman Scattering ◽  
Low Temperatures ◽  
High Pressures ◽  
Mercuric Iodide

Raman scattering from spin-gap mode in under high pressures

2007 ◽  
Vol 310 (2) ◽  
pp. 1200-1202
Author(s):  
Y. Tanokura ◽  
T. Morita ◽  
S. Ishima ◽  
S. Ikeda ◽  
H. Kuroe ◽  
...  
Keyword(s):  
Raman Scattering ◽  
High Pressures ◽  
Spin Gap ◽  
Gap Mode

scholarly journals Combined Experimental and Theoretical Studies: Lattice-Dynamical Studies at High Pressures with the Help of Ab Initio Calculations

Minerals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1283
Author(s):  
Francisco Javier Manjón ◽  
Juan Ángel Sans ◽  
Placida Rodríguez-Hernández ◽  
Alfonso Muñoz
Keyword(s):  
Raman Scattering ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Phase Change Materials ◽  
High Pressures ◽  
Complete Characterization ◽  
Vibrational Properties ◽  
Theoretical Studies ◽  
Experimental And Theoretical Studies

Lattice dynamics studies are important for the proper characterization of materials, since these studies provide information on the structure and chemistry of materials via their vibrational properties. These studies are complementary to structural characterization, usually by means of electron, neutron, or X-ray diffraction measurements. In particular, Raman scattering and infrared absorption measurements are very powerful, and are the most common and easy techniques to obtain information on the vibrational modes at the Brillouin zone center. Unfortunately, many materials, like most minerals, cannot be obtained in a single crystal form, and one cannot play with the different scattering geometries in order to make a complete characterization of the Raman scattering tensor of the material. For this reason, the vibrational properties of many materials, some of them known for millennia, are poorly known even under room conditions. In this paper, we show that, although it seems contradictory, the combination of experimental and theoretical studies, like Raman scattering experiments conducted at high pressure and ab initio calculations, is of great help to obtain information on the vibrational properties of materials at different pressures, including at room pressure. The present paper does not include new experimental or computational results. Its focus is on stressing the importance of combined experimental and computational approaches to understand materials properties. For this purpose, we show examples of materials already studied in different fields, including some hot topic areas such as phase change materials, thermoelectric materials, topological insulators, and new subjects as metavalent bonding.

Sign in / Sign up

Export Citation Format

Share Document