Introduction Circular dichroism (CD) is form of light absorption spectroscopy that measures the difference in absorbance of right- and left-circularly polarized light (rather than the commonly used absorbance of isotropic light) by a substance. It is applicable for molecules have one or more chiral chromophores . Circular dichroism = ΔA(λ) = A(λ)LCPL - A(λ)RCPL, where λ is the wavelength This technique measured a molecule over a range of wavelengths. All chiral molecules can be studied, particularly in study of large biological molecules. A primary application is in the analysing the conformation of macromolecules or secondary structure (particularly proteins).
The purpose of this lab was to implement the use of a Scanning Electron Microscope (SEM) to examine and analyze metal samples that were subject to different failure tests. These failure tests included tensile tests, impact tests, and fatigue tests. SEM’s are useful because they provide a 3D view of the surface of the material, which improves the ability to examine the failure type at a microscopic level. In addition to this, the resolving power of a SEM is much stronger than that of a standard microscope, which enables the user to obtain much more detailed images of the samples. The experiment was performed by analyzing failure tested samples that were prepared before the experiment.
Because the forces on the tip change as the tip-surface separation changes, the resonant frequency of the cantilever is dependent on this separation. In tapping mode lateral forces almost eliminated and the force is low so there is very less damage to soft smaples. But the problem is low scan rate as compare to contact mode. Non- Contact
The data collected from 20 to 70° in 2θ range with steps size 0.02 and a counting time 1 s/steps. Rietveld analysis was carried out using Full prof program. The surface morphology observations along with chemical composition have been performed using transmission electron microscopy (TEM) at room temperature (JEOL JEM-2100) , scanning electron microscopy (SEM) JEOL-JSM-6390, and atomic fore microscopy (AFM) from SOLVER Next (NT-MDT). Structural information about the various vibrational modes was examined by using micro Raman spectrometer (Jobin-Yvon-Horibra LABRAM-HR 800) with the 488.8 nm laser line as excitation source and FTIR spectrophotometer (Bruker Model Vertex 70). Diffuse reflectance spectra were recorded using Perkin-Elmer Lambda-90 UV–Vis- NIR spectrophotometer and the energy band gap was estimated.
By integrating different functional groups, researchers are able to develop rotaxane sensors for metal ions, anions and even explosives. For example, in 2007, Chen et al. developed a  rotaxane which contains a 2,2’-bipyridinium (BP-H2) ion and crown ether like macrocycle which is responsible for the sensing of 5 physiologically metal ions, including Li+, Na+, K+, Mg2+ and
The evolution of chemical sensors is an active area in analytical research. Physical sensors are mainly to detect physical responses. Biosensors are also type of chemical sensor used to sense the biological activity of proteins, nucleotides, tissues. Sensor consists of receptor and transducer parts. The chemical sensor provides information about the chemical state of the process.
The measured cantilever deflections let a computer to create a map of surface topography. AFMs can be used to study insulators and semiconductors as well as electrical conductors. Atomic Force Microscopy operates in several modes.  a. Contact Mode AFM: Measures topography by sliding the probe tip across sample surface (Figure 6).
1.1 CHEMISTRY Chemistry is the science of molecules and their transformations; it deals with their composition and properties of substances and various elementary forms of matter. Chemistry is the study of matter and the changes which occur in material substances. It is connected to other fields of study and it is precisely useful in all the other fields like Geologist’s used chemical techniques to analyze and identify rock samples on new mineral or oil deposits. Engineers identify materials for their uses and estimate the relationship between the structure and properties of substances. Physicist detects the new subatomic particles by expressing the different properties of substance.
Here angles of red light are larger than blue light. Red light is the long wavelengths and Blue light is short wavelengths. (3) Fig 2: Grating Spectrometer Amplitude and Phase Grating: In this fig we can see both Amplitude and Phase gratings. When an incident light pass through on the material can pass through the gaps on the substrate and transmit through it and remaining light reflects. In phase grating light can pass through both the gaps and top of the substrate, so the reflected light has phase shift.
This includes the modifications with amino terminal such as TOPSi-NH2 and TCPSI-NH2 (Wunjun et al. 2012). TOPSi-NH2 UnTHCPSi-COOH Figure 4: Modified and stabilized surfaces of Psi nanoparticles (Kovalainen et al. 2012) 1.6 Drug loading properties of PSi Loading of drugs into PSi nanoparticles is carried out by capillary action and the drugs are retained either by physical trapping, covalent attachment or spontaneous adsorption. The chemical nature of the drug and the loading solution has also been reported to have effect on loading into porous silicon particles (Salonen et al.