Carbon Diamond Graphite Organic

Raman spectroscopy is a good technique for qualitative analysis and discrimination of organic and/or inorganic compounds in mixed materials. A Raman spectrum can be obtained from samples that are as small as 1 xm. The intensities of bands in a Raman spectrum depend on the sensitivity of the specific vibrations to the Raman effect and are proportional to concentration. Thus, Raman spectra can be used for semiquantitative and quantitative analyses. The technique is used for identification of organic molecules, polymers, biomolecules, and inorganic compounds both in bulk and as individual particles. Raman spectroscopy is particularly useful in determining the structure of different types of carbon (diamond, graphitic, diamond-like-carbon, etc.) and their relative concentrations. 

Organic substances such as methane, naphthalene, and sucrose, and inorganic substances such as iodine, sulfur trioxide, carbon dioxide, and ice are molecular solids. Salts such as sodium chloride, potassium nitrate, and magnesium sulfate have ionic bonding structures. All metal elements, such as copper, silver, and iron, have metallic bonds. Examples of covalent network solids are diamond, graphite, and silicon dioxide. 

In this chapter, the structures and textures of carbons at different scales are explained. The carbon materials are classified into four families, diamond, graphite, fullerene, and carbyne on the basis of hybridized sp3, flat sp2, curved sp2, and sp orbitals used, respectively. Each family has its own characteristic diversity in structure and also in the possibility of accepting foreign species. The formation of these carbon materials from organic precursors (carbonization) is shortly described by dividing the process into three phases (gas, solid, and liquid), based on the intermediate phases formed during carbonization. The importance of nanotexture, mainly due to the preferred orientation of the anisotropic BSU in the graphite family, i.e., planar, axial, point, and random orientation schemes, is particularly emphasized. 

We don t normally think of elemental carbon as an organic compound. Historically, carbon was known to exist as three allotropes (elemental forms with different properties) amorphous carbon, diamond, and graphite. 

Diamond, graphite, and other forms of carbon are taken directly from mines in the earth. Diamond and graphite can also be made in laboratories. Synthetic diamonds, for example, are made by placing pure carbon under very high pressures (about 800,000 pounds per square inch/56,000 kilograms per square centimeter) and temperatures (about 4,900°F/2,700°C ). The carbon is heated and squeezed in the same way organic material is heated and squeezed in the earth. Today, about a third of all diamonds used are synthetically produced. 

Although it constimtes only about 0.09 percent by mass of Earth s crust, carbon is an essential element of living matter. It is found free in the form of diamond and graphite (see Figure 8.17), and it is also a component of natural gas, petroleum, and coal. (Coal is a natural dark-brown to black solid used as a fuel it is formed from fossilized plants and consists of amorphous carbon with various organic and some inorganic compounds.) Carbon combines with oxygen to form carbon dioxide in the atmosphere and occurs as carbonate in limestone and chalk. 

Any molecule, or compound, that contains carbon atoms is referred to as organic. The usage of this term is a bit arbitrary, though, as some forms of carbon (like graphite and diamond) and carbon-containing ions (like formate and carbonate) are not thought of... 

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