. After reflection of the two beams, they recombine at the beam-splitter. Depending on the location of the moving mirror, difference in the optic paths are generated. The two beams interfere constructively and therefore lead to a maximum detector response when they are in phase with each other. The beams interfere destructively when they are out of phase with each other. (14)(15) Figure 1.3 – Schematic representation of the operation of a FTIR spectrometer equipped with a Michelson interferometer. The interferogram obtained from a monochromatic source is illustrated (John 2006 (15)).
Raman spectroscopy
Raman spectroscopy is, besides IR spectroscopy, one of the two spectroscopic methods used for vibrational analysis. Both techniques are used to provide a fingerprint of molecules by generating spectra. The main difference is that IR spectroscopy is based on absorption of photons with a frequency equal to the vibrational frequency of functional groups, whereas Raman spectroscopy is based on inelastic scattering of monochromatic light. (14) Also different selection rules apply on these techniques, meaning the techniques are
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The area under the curve represents the energy required to compensate for the thermal events of the sample. Some instruments represent endothermic processes (melting) as downward curves and exothermic processes (crystallisation) as upwards peaks, while other instruments show it in the opposite way. (18) DSC can be used to evaluate different thermal events including melting, solid-state transitions, crystallization, glass transitions … (19) DSC may therefore be used to differentiate between polymorphs according to their melting point or to examine the transformation of metastable systems. It is essential though to confirm the results of DSC with other characterization techniques such as Raman spectroscopy, IR spectroscopy and X-ray diffraction.
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.
The nano-thermal analysis method is capable of studying the specific regions of a sample irrespective of its composition. In a multi-component sample, the analysis methods make it possible for the researchers to distinguish between the different components and identify the different characteristics found in each of the sample (Craig, 2002). During the analysis of any sample, the nano-thermal method does not necessarily require the physical alteration of the sample. In its place, it is capable of analyzing any sample through surface studies.
This specific lab will focus on the two main variants of Atomic Absorption Spectroscopy: flame AA spectroscopy, and spectroscopy using a graphite furnace. The lab will also introduce and teach how to deal with both systematic and random error when using Atomic Absorption Spectroscopy.
The objective of this experiment was to identify a metal based on its specific heat using calorimetry. The unknown metals specific heat was measured in two different settings, room temperature water and cold water. Using two different temperatures of water would prove that the specific heat remained constant. The heated metal was placed into the two different water temperatures during two separate trials, and then the measurements were recorded. Through the measurements taken and plugged into the equation, two specific heats were found. Taking the two specific heats and averaging them, it was then that
At very low supersaturation levels, say less than a few percent relative to ice, crystals grow mostly as simple hexagonal prisms. The aspect ratio (ratio of sizes along the a-axis and c-axis) varies somewhat with temperature at low supersaturation, changing from plates (-2 C) to columns (-5 C) to plates (-15 C) and back to columns again (-30 C).
VITIS/ Visible and Infrared Thermal Imaging Spectrometer: its purpose is to assess the component of the solids in the nucleus as well as the various gases found in the coma of the comet (the next layer after the nucleus);
It has been successfully applied to the elemental analysis of various materials, including those of forensic interests [5]. Its growing attraction is due to its high sensitivity, rapid results, and virtually micro-destructive features, just to name a few. Its versatility and low-cost adaptation of atomic emission spectroscopy, has been utilized effectively to the forensic analysis of counterfeit currency, drugs, explosives, fingerprints, ink and paper, glass, gunshot residue, and many other items of specific forensic interests. The method requires little to no sample preparation and can simultaneously provide information on major, minor and trace element compositions [5]. LIBS also has the potential to be used in real time on the field for direct or stand-off analysis. The instrumentation needed is reasonably simple, very robust, and is also available in a compact format the enables portable
TLC allows identification of compounds based on polarity. Nonpolar compounds move higher up on the TLC plate than polar compounds because polar compounds are more attracted t...
1.9.1: Melting point51- A pure crystalline organic compound has a definite and sharp melting point, that is, the melting point range (the difference between the temperature at which the sample collapse or at which the sample becomes completely liquid) does not exceed above 0.5oC. If any miscible or partially miscible impurities are present in small quantity it will increase the melting point range and cause the initiation the melting to occur at a temperature lower than the melting point of the pure substance. The melting point of a solid is the temperature at which it changes state from solid to liquid at atmospheric pressure. At the melting point the solid and liquid phase exists in equilibrium. The melting point of substance depends on pressure and is usually specified at standard pressure. But when temperature is reverse changes from liquid to solid, it is referred to as the freezing point or crystallization point.
Spectroscopy Spectroscopy is the study of energy levels in atoms or molecules, using absorbed or emitted electromagnetic radiation. There are many categories of spectroscopy eg. Atomic and infrared spectroscopy, which have numerous uses and are essential in the world of science. When investigating spectroscopy four parameters have to be considered; spectral range, spectral bandwidth, spectral sampling and signal-to-noise ratio, as they describe the capability of a spectrometer. In the world of spectroscopy there are many employment and educational opportunities as the interest in spectroscopy and related products is increasing.
Before you can observe with a Newtonian reflector telescope, you need to align or collimate its optical parts. The goal of collimation is to insure that both the primary and secondary mirrors as well as the eyepiece are correctly lined up to give clear, sharp views.
A Spectrophotometer is employed to measure the amount of light that a sample absorbed. The instrument operates by passing a beam of light through a sample and measuring the intensity of light reaching a detector. A Spectrophotometer consists of two instruments; one is a Spectrometer used for producing light of any selected color (wavelength) and second is a Photometer used for measuring the intensity of light.
Connect oscilloscope to amplifier. Modulate laser as before. Point laser towards photo detector. Perform measurements of voltage output for different frequencies. Take
Plontke, R. (2003, March 13). Chemnitz UT. TU Chemnitz: - Technische Universität Chemnitz. Retrieved April 1, 2014, from http://www.tu-chemnitz.de/en/
Bisecting the fixed mirror and the movable mirror is a beamsplitter, where a collimated beam of radiation which could be infrared light emitted by an external source (Globar, metal wire, Nernst bar ), can be partially reflected to the fixed mirror (at point F for the median ray) and partially transmitted to the movable mirror (at point M). When the beams return to the