Introduction to Applications of the Raman Spectroscopy to Experimental Mechanics

2015 ◽  
Vol 240 ◽  
pp. 49-54
Author(s):  
Marek Sikoń ◽  
Bogusław Rajchel ◽  
Jadwiga Kwiatkowska ◽  
Alicja Strzała
Keyword(s):  
Raman Spectroscopy ◽  
External Load ◽  
Laser Light ◽  
Mechanical Load ◽  
Experimental Mechanics ◽  
Mechanical State ◽  
State Of Stress ◽  
The Continuum

In this work, the mechanical state of the material is considered in the form of the oscillation of the molecule. The analysis is carried out for material without an external load and for material under the action of the mechanical load. These two states are tested in a Raman spectroscope where oscillations of molecule with modulations are induced by laser light. One should expect that the results of these investigations will confirm the capability of Raman spectroscopy in analysis of molecular mechanical state of material.This research is carried out using photoelastic material, and an analogy to state of stress on the continuum level is presented by photoelastisity.

Transient Light Emissions from a Laser Perturbed Plasma

1972 ◽  
Vol 50 (19) ◽  
pp. 2338-2347 ◽  
Author(s):  
H. A. Baldis ◽  
R. A. Nodwell ◽  
J. Meyer
Keyword(s):  
Laser Pulse ◽  
Electron Density ◽  
Laser Light ◽  
Line Emission ◽  
Argon Plasma ◽  
Stark Broadening ◽  
Excited Atoms ◽  
Electron Density Gradient ◽  
Transient Plasma ◽  
The Continuum

The interaction between a 20 MW Q-switched ruby laser pulse and a partially ionized argon plasma has been studied experimentally. When the focused laser pulse is fired into the plasma, a transient emission from the plasma may be observed both in the continuum and line emission. From measurements of the absolute intensities of this transient radiation, estimates have been made of the population density of the excited atoms and of the electron densities. The Stark broadening of the Ar II lines has also been measured to obtain the electron density in the transient plasma and data obtained in this way are consistent with those obtained from the continuum radiation. During the time when the laser light is incident on the plasma the Ar II lines show a strong asymmetry which disappears quickly after the laser pulse has terminated. This asymmetry can be explained in terms of the electron density gradient present in the expanding perturbed plasma.

scholarly journals Measurement of the state of stress in silicon with micro-Raman spectroscopy

2004 ◽  
Vol 96 (12) ◽  
pp. 7195-7201 ◽  
Author(s):  
Stephen J. Harris ◽  
Ann E. O’Neill ◽  
Wen Yang ◽  
Peter Gustafson ◽  
James Boileau ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
The State ◽  
Micro Raman Spectroscopy ◽  
State Of Stress

On-Line Monitoring of Chlorosilane Streams by Raman Spectroscopy

1998 ◽  
Vol 52 (1) ◽  
pp. 42-46 ◽  
Author(s):  
Elmer D. Lipp ◽  
Ronda L. Grosse
Keyword(s):  
Raman Spectroscopy ◽  
Laser Light ◽  
Maintenance Costs ◽  
Distillation Columns ◽  
Corrosive Liquid ◽  
Fiberoptic Probe ◽  
Sampling Intervals ◽  
On Line ◽  
Compositional Changes ◽  
532 Nm

On-line Raman spectroscopy was used to monitor the composition of methylchlorosilane streams from distillation columns. A spectrometer was assembled that used 532 nm laser light and a fiberoptic probe that could be inserted into corrosive liquid streams. The spectral regions below 800 cm−1 and near 2250 cm−1 contained strong, distinctive bands that were used to identify and quantitate the species of interest. On-line spectra were recorded at 5 min sampling intervals. Several instances were found where large changes in the composition of the columns were observed. Detection limits of 1000 ppm were generally achievable, and, in favorable circumstances, compositional changes of 100 ppm could be detected. Raman spectroscopy gave much better time resolution than current gas chromatography (GC) monitoring and is also projected to have lower capital and maintenance costs.

Variable-Temperature Raman Studies of Langmuir-Blodgett Multilayers Using Integrated Optical Techniques

1987 ◽  
Vol 41 (2) ◽  
pp. 176-179 ◽  
Author(s):  
E. Barbaczy ◽  
F. Dodge ◽  
J. F. Rabolt
Keyword(s):  
Thin Film ◽  
Raman Spectroscopy ◽  
Constant Pressure ◽  
Laser Light ◽  
Variable Temperature ◽  
Optical Technique ◽  
Langmuir Blodgett ◽  
Integrated Optical ◽  
Raman Study ◽  
Incoming Laser

A unique integrated optical device has been constructed which allows the study of submicron films and Langmuir-Blodgett multilayers at both elevated (100°C) and cryogenic (−125°C) temperatures by Raman spectroscopy. The two-stage coupler maintains a constant pressure on the prism used for coupling the incoming laser light into the thin film whose spectrum is desired. A Raman study of L-B multilayers of cadmium arachidate (CdA) in the −125°C to 100°C illustrates the versatility of the integrated optical technique.

Probing the continuum scattering and magnetic collapse in single-crystalline α−Li2IrO3 by Raman spectroscopy

2020 ◽  
Vol 101 (17) ◽  
Author(s):  
Gaomin Li ◽  
Liang-Long Huang ◽  
Xiaobin Chen ◽  
Cai Liu ◽  
Shenghai Pei ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Single Crystalline ◽  
The Continuum

scholarly journals The Use of Peridynamic Virtual Fibres to Simulate Yielding and Brittle Fracture

2021 ◽  
Author(s):  
Jens Olsson ◽  
Mats Ander ◽  
Chris J. K. Williams
Keyword(s):  
Particle Density ◽  
Fibre Orientation ◽  
The State ◽  
Intermediate Step ◽  
Computationally Efficient ◽  
Accurate Analysis ◽  
State Of Stress ◽  
Griffith Theory ◽  
Equivalent Continuum ◽  
The Continuum

AbstractThe forces in the ‘arms’ joining the particles in a peridynamic analysis depend upon the state of stress in the equivalent continuum and the orientation, length and density of the arms. Short and long arms carry less force than medium length arms as controlled by the weighting kernel. We introduce an intermediate step of imagining a mat of long fibres in which the fibre forces only depend upon the stress, the fibre orientation and the length of fibres per unit volume without the added complexity of the arm lengths. The effect of the arm lengths can then be considered as a separate exercise, which does not involve the continuum properties. The arm length is proportional to size of the particles and the separation of length from the state of stress allows for modelling of variable particle density in the discretisation of a problem domain, which enables computationally efficient accurate analysis. We then introduce the concept of arm elongation to fracture in order to model surface energy in fracture mechanics. This means that shorter arms have a larger strain to fracture than longer arms. Numerical implementation demonstrates that this produces a fracture stress that is inversely proportional to the square root of the crack length as predicted by the Griffith theory [1, 2].

Thermomechanical and Hydrophobic Characterization of Shape Memory Polymers

2009 ◽  
Author(s):  
P. Daniel Warren ◽  
Rafael R. Bernal ◽  
John L. Harper ◽  
Rachelann N. Herlihy ◽  
Jonathan P. Vande Geest
Keyword(s):  
Shape Memory ◽  
Crystalline Structure ◽  
Thermal Energy ◽  
External Load ◽  
Mechanical Load ◽  
Shape Memory Polymers ◽  
Direct Result ◽  
Molecular Architecture ◽  
Original Shape ◽  
Chemical Crosslinks

Shape memory polymers (SMPs) have generated a great amount of interest due to their capacity to recover a programmable shape under an applied stimulus, such as temperature change or light irradation [1, 2]. The SMP is initially synthesized with a specific original shape. This shape can be deformed under a mechanical load and at a temperature (TH) greater than the glass transition temperature, Tg. The application of this deformation coupled with subsequent lowering of the temperature (TC) to below the Tg, can fix the polymer in the newly altered formation even after removal of the external load. Increasing the temperature again, to a point above Tg, then activates the shape memory effect, whereby the original shape can be recovered. This shape memory ability is a direct result of specific molecular architecture. Chemical and physical crosslinks and macromolecular chain entanglements are part of this structure. Chemical crosslinks between segments give form to the original shape. Some of these segments are stimuli-sensitive, in other words, segments can become increasingly elastic with the application of thermal energy. This application of energy causes the crystalline structure of these segments to melt and be easily deformed under external load. This temporary shape can now be maintained with the removal of thermal energy leading to re-crystallization. Recoil in this state is prevented by both the new crystalline structure and entanglements of the segments caused by deformation. Physical crosslinks give the architecture permanence, since the linkages do not degrade with stimulus [3]. Different crosslinker formulations can result in varying types of chemical crosslinks. Variations in the structure lead to alterations in the material properties, such as mechanical characteristics and hydrophobicity.

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