The Varied Causes of Color in Glass

1985 ◽  
Vol 61 ◽  
Author(s):  
K. Nassau
Keyword(s):  
Chalcogenide Glasses ◽  
Water Ligand ◽  
Ligand Field ◽  
Energy Bands ◽  
Metal Compounds ◽  
Chemical Mechanisms ◽  
Doped Glasses ◽  
Blue Eyes ◽  
Physical And Chemical ◽  
Ice Water

ABSTRACTAll but two of the fifteen physical and chemical mechanisms which are necessary to explain all the varied causes of color apply in one way or another to glass. These fifteen causes of color derive from a variety of physical and chemical mechanisms and are summarized in five groups with concentration on those mechanisms that apply to glass and the related glazes and enamels. Vibrations and simple excitations explain the colors of incandescence (e.g. flames, hot glass), gas excitations (neon tube, aurora), and vibrations and rotations (blue ice, water, glasses based on water). Ligand field effect colors are seen in transition metal compounds (turquoise, chrome oxide green, glasses based on copper sulfate) and impurities (ruby, emerald, many doped glasses). Molecular orbitals explain the colors of organic compounds (indigo, chlorophyll, organic glasses) and charge transfer compounds (blue sapphire, lapis lazuli, “beer-bottle” brown and chromate glasses). Energy bands are involved in the colors of metals and alloys (gold, brass, glassy metals), of semiconductors (cadmium yellow, vermillion, chalcogenide glasses), doped semiconductors (blue and yellow diamond), and color centers (amethyst, topaz, irradiated glass). Geometrical and physical optics are involved in the colors derived from dispersive refraction (rainbow, green flash, glass prism spectrum), scattering (blue sky, blue eyes, red sunset, ruby gold and opal glasses), interference (soap bubbles, iridescent beetles, cracks in glasses, interference filters), and diffraction (the corona aureole, diffraction grating spectrum).

scholarly journals Changes in Optical Properties upon Dye–Clay Interaction: Experimental Evaluation and Applications

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 197
Author(s):  
Giorgia Giovannini ◽  
René M. Rossi ◽  
Luciano F. Boesel
Keyword(s):  
Optical Properties ◽  
Hybrid Materials ◽  
High Performance ◽  
Fluorescent Properties ◽  
Chemical Mechanisms ◽  
Strong Electrostatic Interaction ◽  
Potential Applications ◽  
Photochemical Properties ◽  
Physical And Chemical ◽  
The Relationship

The development of hybrid materials with unique optical properties has been a challenge for the creation of high-performance composites. The improved photophysical and photochemical properties observed when fluorophores interact with clay minerals, as well as the accessibility and easy handling of such natural materials, make these nanocomposites attractive for designing novel optical hybrid materials. Here, we present a method of promoting this interaction by conjugating dyes with chitosan. The fluorescent properties of conjugated dye–montmorillonite (MMT) hybrids were similar to those of free dye–MMT hybrids. Moreover, we analyzed the relationship between the changes in optical properties of the dye interacting with clay and its structure and defined the physical and chemical mechanisms that take place upon dye–MMT interactions leading to the optical changes. Conjugation to chitosan additionally ensures stable adsorption on clay nanoplatelets due to the strong electrostatic interaction between chitosan and clay. This work thus provides a method to facilitate the design of solid-state hybrid nanomaterials relevant for potential applications in bioimaging, sensing and optical purposes.

Physical and chemical mechanisms of influence of Cu-containing additives on grease properties

1994 ◽  
Vol 6 (2) ◽  
pp. 117-131
Author(s):  
Y. Ischuk ◽  
A. Karaulov ◽  
M. Lukiniuk ◽  
Z. Melnik ◽  
O. Nosovsky
Keyword(s):  
Chemical Mechanisms ◽  
Physical And Chemical

scholarly journals Plasma-deposited hydrogenated amorphous silicon films: multiscale modelling reveals key processes

RSC Advances ◽  
2017 ◽  
Vol 7 (31) ◽  
pp. 19189-19196 ◽  
Author(s):  
Z. Marvi ◽  
S. Xu ◽  
G. Foroutan ◽  
K. Ostrikov ◽  
I. Levchenko
Keyword(s):  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Film Structure ◽  
Multiscale Modelling ◽  
Structure And Properties ◽  
Growth Processes ◽  
Chemical Mechanisms ◽  
Physical And Chemical ◽  
Hydrogenated Amorphous

Physical and chemical mechanisms and role of plasma in the synthesis of hydrogenated amorphous silicon were studied numerically to reveal the key growth processes and, hence, to ensure a higher level of control over the film structure and properties.

Microplastics: Are they really a threat to groundwater systems?

2020 ◽  
Author(s):  
Ahmad Ameen ◽  
Margaret Stevenson ◽  
Alfred Paul Blaschke
Keyword(s):  
Land Surface ◽  
United Nations Environment Programme ◽  
Natural Environments ◽  
Key Factors ◽  
Ongoing Research ◽  
Chemical Mechanisms ◽  
Emerging Pollutant ◽  
Groundwater Systems ◽  
Transport Behaviour ◽  
Physical And Chemical

<p>Recently, global annual plastics production has reached a record of 359 million tonnes and in Europe nearly 62 million tonnes, with only a small portion (6-26%) being recycled. Plastic debris released into the environment are categorized, according to size, as macroplastics (> 5mm), microplastics (0.1μm - 5mm) and nanoplastics (< 0.1μm). Microplastics are now recognized as an emerging pollutant due to their abundance in natural environments, and because of growing concerns, the United Nations Environment Programme (UNEP) has included it in the list of top 10 environmental problems.</p><p>Additionally, microplastics have a tendency to act as a vector for other contaminants such as pathogens, organic pollutants and heavy metals due to strong dispersion and diffusion mechanisms. The majority of ongoing research on microplastics has primarily focussed on marine systems, but land surface contamination may also be important due to observed release rates that are approximately 20 times higher, in comparison to oceans. Nevertheless, only a few studies have addressed the presence of microplastics in soil and groundwater.</p><p>A research gap exists regarding the physical and chemical mechanisms that govern microplastic transport and retention in groundwater. Therefore, a study is being conducted to investigate the distribution, fate and transport of microplastics through groundwater. The overall aim is to improve the understanding of the transport mechanisms of these emerging pollutants and if they enhance the mobility of microbial communities. This research has two main objectives: firstly, to simulate the transport behaviour of various kinds of microplastics (different types, shapes, sizes, and surface morphology), secondly, to analyse the microplastics as potential vectors for microorganisms.</p><p>The key factors that are affecting the transport of different sized microplastics will be addressed. Additionally, the co-transport of microorganisms with microplastics during their movement within soil and groundwater will also be considered.</p>

Assessing the role of nudging, aerosols and run-up time in medicane simulations with WRF

2020 ◽  
Author(s):  
Juan José Gómez-Navarro ◽  
Enrique Pravia-Sarabia ◽  
Juan Pedro Montávez
Keyword(s):  
Small Scale ◽  
Factors Affecting ◽  
Chemical Mechanisms ◽  
Spectral Nudging ◽  
On Line ◽  
Precise Prediction ◽  
Considerable Impact ◽  
Run Up ◽  
Physical And Chemical

<p>Medicanes are small-scale cyclones with tropical characteristics that take place in the Mediterranean basin, showing hazardous features such as intense wind gusts and precipitation. Our ability to predict their consequences is of great importance for those cases of medicanes reaching coastal inhabited areas. Succeeding in a precise prediction of their characteristics is heavily subject to getting insight in the fundamental factors that are involved in their genesis, strengthening and maintenance. Given their small nature compared to the synoptic scale, RCMs are specially suitable for the simulation of these storms. However, when using RCMs, there are a number of configurations that must be controlled to specify the way the different physical and chemical mechanisms are solved during the simulation.<br><br><br>In this work, we evaluate the role of three different factors affecting the outcome of WRF, namely the run-up time, the inclusion or not of the on-line simulation of aerosols and the use of spectral nudging. To that end, six different medicanes have been simulated combining different possibilities for the aforementioned factors, resulting in a set of above 360 simulations. Although in principle the on-line simulation of aerosols is expected to have the strongest impact in the simulation of medicanes, it turns out that the run-up time -time delay from the simulation start to the medicane maximum intensity moment- is far more decisive in their successful development than the former. The results are also sensible to the use of spectral nudging, and the three considered factors end up having a considerable impact. Indeed, whereas the majority of their combinations lead to an erratic reproduction of the observed medicanes, there exist some combinations that allow reasonable results, showing that these configurations are in fact interdependent, i.e., the change in the simulation outcome due to a different configuration for one of the factors is dependent on the configuration of the others. This complicates the assessment on the influence of one factor alone, but facilitates gaining insight on the factors that control the genesis and maintenance of medicanes.</p>

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