scholarly journals Observing the emergence of phase biaxiality in a polar smectic A system via polarised Raman spectroscopy

2017 ◽  
Vol 5 (5) ◽  
pp. 1195-1205 ◽  
Author(s):  
Z. Zhang ◽  
S. Kaur ◽  
B. Kundu ◽  
B. K. Sadashiva ◽  
H. F. Gleeson
Keyword(s):  
Raman Spectroscopy ◽  
Dielectric Properties ◽  
Smectic A ◽  
Smectic Phases ◽  
Insight Into

We report polarised Raman spectroscopy, and optical and dielectric properties of an asymmetric bent-core compound offering a new insight into the emergence of phase biaxiality in polar smectic phases.

Freeze-fracture TEM of the helical smectic A* phase

1992 ◽  
Vol 50 (1) ◽  
pp. 278-279
Author(s):  
K.J. Ihn ◽  
R. Pindak ◽  
J. A. N. Zasadzinski
Keyword(s):  
Liquid Crystal ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Freeze Fracture ◽  
Smectic Phase ◽  
Layer Spacing ◽  
Screw Dislocations ◽  
Smectic A ◽  
Smectic Phases ◽  
Discrete Amount

A new liquid crystal (called the smectic-A* phase) that combines cholesteric twist and smectic layering was a surprise as smectic phases preclude twist distortions. However, the twist grain boundary (TGB) model of Renn and Lubensky predicted a defect-mediated smectic phase that incorporates cholesteric twist by a lattice of screw dislocations. The TGB model for the liquid crystal analog of the Abrikosov phase of superconductors consists of regularly spaced grain boundaries of screw dislocations, parallel to each other within the grain boundary, but rotated by a fixed angle with respect to adjacent grain boundaries. The dislocations divide the layers into blocks which rotate by a discrete amount, Δθ, given by the ratio of the layer spacing, d, to the distance between grain boundaries, lb; Δθ ≈ d/lb (Fig. 1).

In situ loading of well-dispersed silver nanoparticles on nanocrystalline magnesium oxide for real-time monitoring of catalytic reactions by surface enhanced Raman spectroscopy

Nanoscale ◽  
2015 ◽  
Vol 7 (40) ◽  
pp. 16952-16959 ◽  
Author(s):  
Kaige Zhang ◽  
Gongke Li ◽  
Yuling Hu
Keyword(s):  
Raman Spectroscopy ◽  
Surface Enhanced Raman Spectroscopy ◽  
Catalytic Reactions ◽  
Reaction Intermediates ◽  
Reaction Conditions ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Nanocrystalline Magnesium Oxide ◽  
Insight Into

The surface-enhanced Raman spectroscopy (SERS) technique is of great importance for insight into the transient reaction intermediates and mechanistic pathways involved in heterogeneously catalyzed chemical reactions under actual reaction conditions, especially in water.

Shining light on low-temperature methanol aqueous-phase reforming using homogeneous Ru-pincer complexes – operando Raman-GC studies

2017 ◽  
Vol 2 (3) ◽  
pp. 390-396 ◽  
Author(s):  
Vinzent Strobel ◽  
Julian Jonathan Schuster ◽  
Andreas Siegfried Braeuer ◽  
Lydia Katharina Vogt ◽  
Henrik Junge ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Low Temperature ◽  
Aqueous Phase ◽  
Volume Flow ◽  
Pincer Complexes ◽  
Methanol Reforming ◽  
Aqueous Phase Reforming ◽  
Flow Monitoring ◽  
Insight Into

A combination of operando Raman spectroscopy with online GC and volume-flow monitoring allows rapid insight into low-temperature methanol reforming.

Optical Diagnostics of Microstructures Fabricated Using Quantum Well Intermixing

1999 ◽  
Vol 607 ◽  
Author(s):  
A. Saher Helmy ◽  
A.C. Bryce ◽  
C.N. Ironside ◽  
J.S. Aitchison ◽  
J.H. Marsh ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Quantum Well ◽  
Spatial Resolution ◽  
Optical Diagnostics ◽  
Complete Suppression ◽  
Quantum Well Intermixing ◽  
Spatially Resolved ◽  
Non Destructive ◽  
Insight Into ◽  
Free Vacancy

AbstractIn this paper we shall discuss techniques for accurate, non-destructive, optical characterisation of structures fabricated using quantum well intermixing (QWI). Spatially resolved photoluminescence and Raman spectroscopy were used to characterise the lateral bandgap profiles produced by impurity free vacancy disordering (IFVD) technology. Different features were used to examine the spatial resolution of the intermixing process. Features include 1:1 gratings as well as isolated stripes. From the measurements, the spatial selectivity of IFVD could be identified, and was found to be ∼4.5 μm, in contrast with the spatial resolution of the process of sputtering induced intermixing, which was found to be ∼2.5 μm. In addition, PL measurements on 1:1 gratings fabricated using IFVD show almost complete suppression of intermixing dielectric cap gratings with periods less than 10 microns. Finally, some insight into the limitations and merits of PL and Raman for the precision characterisation of QWI will be presented.

scholarly journals Effect of Ionic Liquids on the Physical Properties of the Newly Synthesized Conducting Polymer

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Dong Uk Lee ◽  
Jin Yeong Jeong ◽  
Ji Woong Han ◽  
Gi-Chung Kwon ◽  
Pankaj Attri ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Ionic Liquids ◽  
Conducting Polymer ◽  
Optical Devices ◽  
Polymer Mixtures ◽  
Confocal Raman Spectroscopy ◽  
Vis Spectroscopy ◽  
Film Roughness ◽  
Confocal Raman ◽  
Insight Into

Conducting polymer has many applications in electronics, optical devices, sensors, and so on; however, there is still a massive scope of improvement in this area. Therefore, towards this aim, in this study, we synthesized a new thiophene-based conducting polymer, 2-heptadecyl-5-hexyl-6-(5-methylthiophen-2-yl)-4-(5-((E)-prop-1-enyl)thiophen-2-yl)-5H-pyrrolo[3,4-d]thiazole (HHMPT). Further, to increase its application, the interactions between the conducting polymer (HHMPT) and ionic liquids (ILs) were investigated by UV-Vis spectroscopy, FTIR spectroscopy, and confocal Raman spectroscopy techniques. Moreover, film roughness and conductivity of the polymer film with or without ILs were also studied. The imidazolium- and ammonium family ILs with the potential to interact with the newly synthesized conducting polymer were used. The results of the interaction studies revealed that the imidazolium family IL-polymer mixtures and ammonium family IL-polymer mixtures have almost similar conductivity at low concentration of ILs. This study provides an insight into the combined effect of a polymer and ILs and may generate many theoretical and experimental opportunities.

Polymorphism of Smectic Phases with Smectic a Morphology

1970 ◽  
pp. 321-332 ◽  
Author(s):  
Sardari L. Arora ◽  
Ted R. Taylor ◽  
James L. Fergason
Keyword(s):  
Smectic A ◽  
Smectic Phases

Fertilization state ofAscaris suumdetermined by electrorotation

2006 ◽  
Vol 80 (1) ◽  
pp. 25-31 ◽  
Author(s):  
C. Dalton ◽  
A.D. Goater ◽  
H.V. Smith
Keyword(s):  
Dielectric Properties ◽  
Physicochemical Properties ◽  
Parasitic Nematode ◽  
Invasive Technique ◽  
Non Invasive ◽  
Egg Morphology ◽  
Parasite Biology ◽  
Response Modelling ◽  
Non Destructive ◽  
Insight Into

AbstractElectrorotation is a non-invasive technique that is capable of detecting changes in the morphology and physicochemical properties of microorganisms. The first detailed electrorotation study of the egg (ovum) of a parasitic nematode, namelyAscaris suumis described to show that electrorotation can rapidly differentiate between fertilized and non-fertilized eggs. Support for this conclusion is by optical microscopy of egg morphology, and also from modelling of the electrorotational response. Modelling was used to determine differences in the dielectric properties of the unfertilized and fertilized eggs, and also to investigate specific differences in the spectra of fertilized eggs only, potentially reflecting embryogenesis. The potential of electrorotation as an investigative tool is shown, as undamaged eggs can be subjected to further non-destructive and destructive techniques, which could provide further insight into parasite biology and epidemiology.

Far-infrared, Raman spectroscopy, and microwave dielectric properties of La(Mg0.5Ti(0.5−x)Snx)O3 ceramics

2007 ◽  
Vol 102 (6) ◽  
pp. 064906 ◽  
Author(s):  
G. Santosh Babu ◽  
V. Subramanian ◽  
V. R. K. Murthy ◽  
I-Nan Lin ◽  
Chia-Ta Chia ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Dielectric Properties ◽  
Microwave Dielectric Properties ◽  
Far Infrared ◽  
Microwave Dielectric
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