Scanning electron microscopy (SEM) technique was employed extensively through want this study to examine and obtain images of prepared samples. The associated analytical facility of Energy dispersive X-Ray (EDX) analysis was used to identify and quantify the elemental composition of the prepare samples.
These different techniques are essentially part of one instrument. The EDX facility (an X-Ray detector and associated software) is incorporated intimately as part of the SEM itself. The EDX facility cannot function without the operation of the SEM, since the generation of the analytical X-Ray signal is dependent on the interaction between the incident electron seam and the sample in the SEM. EDAX() and DES (Energy Dispersive Spectrometer) are often used interchangeably in place of EDX by different instrument manufactures but are essentially the same technique.
There are mainly three types of Electron microscope
1. Scanning Electron Microscope (SEM)
2. Transmission Electron Microscope (Tem)
3. Dual function capability: Scanning – Transmission Electron Microcopy (STEM).
An electron gun is present in a Scanning Electron Microscope to generate a beam of electrons in a high vacuum column. With the help of an accelerating voltage of between 1.0 to 30 kV, the emitted electrons are converted into a coherent beam by using a system of electromagnetic coils or lenses. Then the beam passed down through the main electron gun column into the specimen chamber. Here it is focused onto a fine spot. Then the surface of the sample is scanned rapidly.
As the result of ionization processes secondary electrons are emitted from the sample. From the primary beam (generated by the electron gun) some electrons are get reflected or bounced back by the sampl...
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...hich describes the angle at which a beam of X-rays of a particular wavelength diffracts from a crystalline surface. Bragg’s Law is as follows:
ƛ=2d sinθ
Where:
θ = Bragg angle;
ƛ = is the incident wavelength; d= is the spacing between different planes.
We can measure the Bragg angle (2θ). This is the position of the Bragg reflection, or peak. Then, since we know the wavelength (ƛ), of the X-rays, we can then calculate the d-spacing (the distance between different planes in the crystal) from Bragg’s Law (Equation 3-36)
A typical X-ray diffraction pattern is in the form of a graph, with a series of peaks (the actual diffraction pattern), with the horizontal axis being 2θ, or twice the Bragg angle; and the vertical axis is the intensity, or the X-ray count measured by the detector, which is a function of the crystal structure and the orientation of the crystallites.
The purpose of the Unknown White Compound Lab was to identify the unknown compound by performing several experiments. Conducting a solubility test, flame test, pH paper test, ion test, pH probe test, conductivity probe test, and synthesizing the compound will accurately identified the unknown compound. In order to narrow down the possible compounds, the solubility test was used to determine that the compound was soluble in water. Next, the flame test was used to compare the unknown compound to other known compounds such as potassium chloride, sodium chloride, and calcium carbonate. The flame test concluded that the cation in the unknown compound was potassium. Following, pH paper was used to determine the compound to be neutral and slightly
The primary goal of this laboratory project was to identify an unknown compound and determine its chemical and physical properties. First the appearance, odor, solubility, and conductivity of the compound were observed and measured so that they could be compared to those of known compounds. Then the cation present in the compound was identified using the flame test. The identity of the anion present in the compound was deduced through a series of chemical tests (Cooper, 2009).
The technique used to narrow down the identity of unknown white compound were solubility test, pH test, flame test, and ion test. The first technique used to narrowed the properties of unknown white compound was using solubility test. To conduct solubility test, 0.25 gram of unknown white compound was dissolved in 100 mL of water. After carefully observing the change while string unknown white compound in water, the unknown white compound was soluble because it dissolved in water completely. Using bursen burner, matches and deionized water, flame test was conducted for unknown compound and it burned lilac color. Then compared the color of unknown white compound to other compound that were narrowed. The results of flame test for compounds that were narrowed down is shown in the following table. The pH test was conducted using litmus paper. 0.50 gram of unknown white compound was measured and dissolved in 10 mL of water in beaker. After dissolving, placed the litmus paper in solution and recorded the pH value of unknown compound which was neutral. Then compared the pH value of unknown white compound to compound that were narrow down. The pH result of the KCL, KNO3, NaCl, and K2SO4 is presented in the following table. The ion test was also conducted in order to make sure that the identity of unknown white compound was matched with the compound that were narrow down. After conducting the test, the result of unknown white compound which formed precipitate compared to KCl, KNO3,NaCl, and K2SO4. The results shown in the following
In the TEM, a beam of electrons is passed through thin, specially prepared slices of material. As the molecules in the air would absorb the electrons, a vacuum has to be created within the instrument. Where electrons are absorbed by the material, and do not therefore reach the screen, the image is dark. Such areas are said to be electron dense. Where electrons penetrate, the screen appears bright.
Band-gap is the difference in the energy levels between these two states of valance band (VB) and conduction band (CB). When photons of energy E≥Eb are incident on a bandgap material, a photo-generated electron is excited to the conduction band
A bone density test is the primary exam used to diagnose osteoporosis. According to the National Osteoporosis Foundation (2016), “a bone density test is the only test that can diagnose osteoporosis before a broken bone occurs.” A DXA scan is a type of bone density test and it stands for dual energy x-ray absorption. The DXA scan analyses the bone density in the hip and spine. The DXA machine sends a beam of low dose x-rays into the bones being examined. The soft tissues absorb a portion of the x-ray and the bones absorb the rest. The amount of energy absorbed by the soft tissues can be subtracted from the total amount introduced into the body and the remaining amount is the bone mineral density. To perform a DXA scan, the patient is
In a laboratory scientist will use a process called gel electrophoresis to separate DNA fragments. The DNA is cut into different sized fragments as a result from using restriction enzymes. The different sized DNA fragments are organized injected on agarose gel with an added substance that helps it glow after the test. DNA is negatively charged. Electricity is producing a positively charged are and a negatively charged area. Opposites attract and as a result the negatively charged DNA will move quickly to the positively charged area. Smaller DNA fragments will run faster the larger DNA fragments. After the electricity is turned off smaller DNA fragments will be closer to the positively charged area and the larger DNA fragments will be farther from the positively charged area. While it is glowing scientist can take a picture of the data and record the results and compare DNA samples to look for any abnormalities.
By doing this experiment, I can know the physical and chemical properties of these samples. After I get my results about the physical and chemical properties of these samples, I can compare my results with the information given by the past student and identify the 5 unknown samples, finding out which sample is which substance. Hypothesis = ==
Compound Light Microscope is a device that uses visible light and magnifying lenses to search tiny objects that are not visible to the naked eye, or finer detail than the naked eye allows. Samples you can use with this device is a leaf, bug, or feather, but it is very blurry and pale color. The microscope works by an eyepiece, ocular lens, the field of view, focus dials, supporting arm, rack stop, objective lenses, slides, cover slips, and many other things. It works by the light source is below the stage, and this light shines up through the thin specimen and then through the magnifying lenses. Prepared the specimen for viewing by placing it on a regular glass side. It can be stained with a dye that contract to nearly transparent
Wilhelm Roentgen investigated the light phenomena and other emissions created by releasing electrical currents in Crookes tubes, and glass bulbs, evacuated of air, with negative and positive electrodes. When a high voltage current was sent through these bulbs, a fluorescent glow would be displayed in them. During this time, Roentgen was studying electrical ray’s path as they were passing from an induction coil through a glass tube that was partially evacuated. For this experiment, the tube he used was in a completely dark room, and it was covered in black paper. Roentgen noticed that the platinobarium screen, which was nine feet away and covered in fluorescent material, was illuminated. He knew that the screen was illuminating due to the rays.
X-Ray “We look to medicine to be an orderly field of knowledge and procedure. But it is not. It is an imperfect science, an enterprise of constantly changing knowledge, uncertain information, fallible individuals, and at the same time lives on the line. There is science in what we do, yes, but also habit, intuition, and sometimes plain old guessing…”
Tesla designed and invented the tesla coil in 1891. The tesla coil is used to transmit- high electricity and high frequency using the rotating magnetic field, and Alternating Current similar to the design he used for the rotating magnetic field. Tesla often experimented using two or sometimes three of the coils. He wanted to pursue these new devices to bring about innovations and discoveries. Tesla was also going to use them to help deliver free energy to the people. He envisioned and believed the Earth to be a big magnet of transmitting electricity. He thought the only thing missing from it was basically a receiver. But his tesla coils helped him bring about the invention of electrical lighting, his very used and widely-known x-ray, electrotherapy, and as I have previously stated, this was his first step at trying to receive energy from the earth. Today, the tesla coil is used for amusement and in some cases, they are used to identify leaks in a vacuum system. So how does the tesla coil work? They start off with a simple spark to set it off. Oscillators, I believe I mentioned them in the history of Tesla, they are basically used to help deliver an oscillating current. The oscillator helps the coils produce currents that can range anywhere from 50 kilovolts to several million volts of electricity. This is what your typical mad scientist use in things such as Frankenstein. Except for Tesla was a very real version of those mad scientists. The tesla coil also had a capacitor in it, they are used to store an electrical current that bursts out to help it create a stronger voltage. I have also read that there is something in it called a spark gap which is a switch in the coil to turn it on. Since I have let you know what the machine consists of, I will now discuss the operation cycle. First, the transformer sends high voltages up to the capacitor. There is something called a breakdown voltage there.
...h cesium ions and then to focus it into a fast moving beam. The ions that are produced become negative, which helps prevents the confusion of Carbon-14 with Nitrogen-14 since Nitrogen does not have a negative ion. The first magnet is used to select ions with an atomic mass of fourteen. The ions then enter the accelerator. As they travel to the terminal, they are accelerated to an incredible speed so when they collide with the gas molecules, all of the molecular ions are broken up and most of the carbon ions have four electrons removed, turning them into Carbon3+ ions. The second magnet selects ions with the speed expected for the Carbon-14 ion and a filter makes sure their momentum is also right. Finally, the filtered Carbon-14 ions enter the detector where their speed and energy are checked so that the number of Carbon-14 ions in the sample can be counted (Oxford).
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.
...ia Britannica. 2014. law of octaves (chemistry) -- Encyclopedia Britannica. [ONLINE] Available at:http://www.britannica.com/EBchecked/topic/424834/law-of-octaves. [Accessed 14 May 2014].