Physical properties of compounds remain an interesting and important area of research since last century. Various physical properties of a compound are depending on vibrations of atoms present in it. Lattice dynamics is considered to be an important tool in studying these atomic vibrations. Lattice dynamical study of a compound gives information about the nature of inter-atomic forces present and helps to understand its bonding and structural properties. Raman and IR spectral studies is an important area in the field of lattice dynamics as it contains rich and valuable information. It gives the information about the structure and chemical composition of the compound. Raman and infrared spectra is used in the identification of the molecule. This data is also helpful in determining the site symmetry occupied by the atom and its exact position within a crystal. Many inorganic complex structured compounds change their structural phase at particular physical conditions. These transitions in the compound from one phase to the other can be determined through the Raman and infrared spectral data. Using this, vibrational frequencies of the compounds can also be identified and assigned on the basis of normal coordinate analysis. In recent years, with rapidly development in science and technology, inorganic complex structured compounds have become the important area of theoretical as well as experimental research. Raman and infrared mode assignment of many recently studied complex structured materials is not available. Therefore, in the present work, the lattice dynamical studies of some of the inorganic complex structured compounds have been carried out in order to identify and assign their Raman and infrared wavenumbers by applying short ... ... middle of paper ... ...he linear variation of force constants with concentration in this compound suggests that this compound exhibits one mode behavior for 0 ≤ x ≤ 0.2. Conclusions A short range force constant model has been applied involving several stretching and bending force constants to evaluate the Raman and infrared wavenumbers of inorganic complex structured compounds Cs2HgCl4, Cs2CdBr4, NaCdAsS3, mixed crystals Ba2-xSrxMWO6 (M = Co, Ni); 0 ≤ x ≤ 1.2 and Bi1-xTa1-xTe2xO4; 0 ≤ x ≤ 0.2. The calculated Raman and infrared modes show a good agreement with the experimental results. For the first time, assignment of the frequencies to specific symmetry modes of some of these compounds has been carried out. Linear variation of force constant with composition suggests one mode behavior in the mixed crystals Ba2-xSrxMWO6 (M = Co, Ni) for 0 ≤ x ≤ 1.2 and Bi1-xTa1-xTe2xO4 for 0 ≤ x ≤ 0.2.
The goal of this experiment is to study the most precise way of measuring molecular bond lengths and introduction to computational software used for studying molecular properties. This is of interest in that the instrument to being used, a Fourier-transform infrared (FT-IR) spectrometer, can measure the vibrational and rotational transitions of the fundamental and first overtone of CO. Through this experiment the objective is to collect data from the aforementioned instrument in order to determine vibrational and rotational spectroscopic constants and CO’s bond length, then to compare them with quantum chemical calculation.
Thermal methods of analysis have been in use for quite a long time. Their application in the analysis of pharmaceutical materials has made it possible for pharmacists and researchers to understand their contents and characteristics. However, thermal methods have several disadvantages that have led researchers to opt for nano-thermal methods of analysis. Nano-thermal analysis methods use special resolution imaging potential that is enhanced by the availability of atomic force microscopy and thermal analysis methods.
Zirconia has three crystalline forms: monoclinic phase, tetragonal phase and cubic phase. Monoclinic phase exists in zirconia stable up to temperature 1170˚C. Above 1170˚C, the monoclinic phase transforms to tetragonal phase and further transform to cubic phase above 2370˚C. While cooling down below 1070˚C, tetragonal phase becomes unstable and start transformation of monoclinic phase. Thus tetragonal phase is hard to exist at the room temperature.
IR spectroscopy measures the absorption of infrared light that corresponds to transitions among different molecular vibrations (Gilbert & Martin 2011). An IR spectroscopy is typically used to determine the presence or absence of functional groups of a given
Nitinol's strange properties are gotten from a reversible strong state stage change known as a martensitic change. At high temperatures, nitinol expect an interpenetrating basic cubic structure alluded to as austenite
The crystal structure (II) is found to be disordered tetragonal, space group P4͞ 21m, a = 5.7193 , c = 4.9326 A0,,Z=2 . The phase (IV) of AN is stable between the temperature -18 and 32.30C. It belongs to the orthorhombic structure with space group Pmmn. It has a coordination number of two. The IV-III transition take place at near temperature about 32 0C. it causes swelling, caking and particle deterioration of stored ammonium nitrate. The IV-III transition only occurs when moisture is present and this transition takes place by the dissolution and recrystallization of the solid . During recystallization process salt bridges are formed between the crystallites. This phase transition is followed by a volume change. It also leads to the ...
The IR spectrum that was obtained of the white crystals showed several functional groups present in the molecule. The spectrum shows weak sharp peak at 2865 to 2964 cm-1, which is often associated with C-H, sp3 hybridised, stretching in the molecule, peaks in this region often represent a methyl group or CH2 groups. There are also peaks at 1369 cm-1, which is associated with CH3 stretching. There is also C=O stretching at 1767 cm-1, which is a strong peak due to the large dipole created via the large difference in electronegativity of the carbon and the oxygen atom. An anhydride C-O resonates between 1000 and 1300 cm-1 it is a at least two bands. The peak is present in the 13C NMR at 1269 and 1299 cm-1 it is of medium intensity.
To examine the interaction between two molecules in solution without isolating the compound Jobfs method is used. Although unstable compounds tend to be generated, this is not a reflection of weak interactions. In some cases, the transition metal species cannot be crystallized from the solution and separated from the other species present. Without Jobfs Method this composition can be very difficult to deduce.
Polman, H., Orobio De Castro, B. & Van Aken, M. A.G. (2008). Experimental Study of the
The dynamic systems view was developed by Arnold Gesell in 1934 and explores how humans develop their motor skills. From Mr. Gesell’s observations, he was able to conclude that children develop their motor skills in a specific order and time frame. He concluded that children roll, walk, sit, and stand as a result of several factors – the ability to move, the environmental support to move and the motivation/goal to move. Once the child has the motivation, ability, and support, they accept the new challenge. After several failed and successful attempts, they begin to fine-tune and master the movement with continued support and motivation. The dynamic systems theory is not a random process that children experience, the skills are calculated and develop over a period of time.
23. S. Alwarappan, S. Boyapalle, A. Kumar, C.-Z. Li and S. Mohapatra, J. Phys. Chem. C, 2012, 116, 6556–6559
Individual atoms can emit and absorb radiation only at particular wavelengths equal to the changes between the energy levels in the atom. The spectrum of a given atom therefore consists of a series of emission or absorption lines. Inner atomic electrons g... ... middle of paper ... ... a sensitive multielement inorganic analyses.
In the last few decades, a new frontier has opened up due to tremendous advancement of semiconductor technology which have brought incredible changes to our society and the life of people. The aim has become to control the optical properties of materials. A massive range of technological developments become possible by engineering of such materials that respond to light waves over a desired range of frequencies. They can perfectly reflect the light waves, or allow them to propagate only in certain directions, or can also confine them within a specified volume [1]. The introduction of components such as optical fibers or integrated ridge waveguides which were based on principle of total internal reflection for light guidance, such as, has bought revolutionary changes in the telecommunication and optical industry. Apart from that another way of controlling light based on Bragg diffraction has already been used in many devices like dielectric mirrors. The principle of dielectric mirrors based on one-dimensional (1D) light reflection was generalized to two and three dimensions in 1987 [2, 3] which leaded to a new class of materials: photonic crystals. Photonic crystals arise from the cooperation of periodic scatterers, therefore they are called crystals because of their periodicity and photonic because they interact with light.
Plontke, R. (2003, March 13). Chemnitz UT. TU Chemnitz: - Technische Universität Chemnitz. Retrieved April 1, 2014, from http://www.tu-chemnitz.de/en/
The development of quantum mechanics in the 1920's and 1930's has revolutionized our understanding of the chemical bond. It has allowed chemists to advance from the simple picture that covalent and ionic bonding affords to a more complex model based on molecular orbital theory.