Spectroscopy - Emission absorption and Scattering.pptx
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Spectroscopy is the study of how electromagetic radiation interacts with matter , specifically focusing on absorption, emission , and scattering of light
Spectroscopy - Emission absorption and Scattering.pptx
- 2. What is spectroscopy Spectroscopy is a scientific technique used to analyze the interaction of light (or other electromagnetic radiation) with matter. It involves measuring the intensity of light as a function of its wavelength, frequency, or energy to gather information about the composition, structure, and properties of a substance. Spectroscopy is a broad and essential analytical technique used across various scientific disciplines to investigate the properties of matter through the interaction of light or other forms of electromagnetic radiation. It allows scientists to obtain detailed information about the composition, structure, and behavior of substances at the atomic or molecular level.
- 3. EMISSION Emission spectroscopy is an analytical technique used to study the light emitted by atoms or molecules when they are excited. When atoms or molecules absorb energy (such as heat or electrical energy), their electrons get excited to a higher energy level. When these excited electrons return to a lower energy state, they release the energy they absorbed in the form of light. This light is emitted at specific wavelengths, which are characteristic of the elements or compounds involved. Excitation: A sample (typically a gas or vapor) is excited by an external energy source such as heat, an electric field, or a laser. The atoms or molecules absorb energy, and their electrons are promoted to higher energy levels (excited states). Emission of Light: As the excited electrons return to their ground state or a lower energy level, they release the excess energy in the form of light. This emitted light is often in the form of visible light, but it can also be ultraviolet or infrared, depending on the energy difference between the excited and lower energy levels.
- 4. Types of Emission Spectroscopy Technique Flame Emission Spectroscopy (FES) Atomic Emission Spectroscopy (AES) Atomic Emission Spectroscopy (AES) Applications of Emission Spectroscopy Environmental Analysis: Detection of pollutants and metals in water, soil, and air samples. Clinical Chemistry: Measurement of trace elements in blood, urine, and other biological samples. Material Science: Characterization of metals, alloys, and other materials for quality control and compositional analysis. Agriculture: Analyzing soil and plant nutrients for better crop management and fertilizer usage.
- 5. ABSORPTION Absorption spectroscopy is an analytical technique used to measure the absorption of light by a sample at different wavelengths. When a substance absorbs light, the energy from the light is transferred to the atoms or molecules in the sample, causing them to move to a higher energy state. The amount of light absorbed at a specific wavelength is related to the concentration of the absorbing species in the sample. This makes absorption spectroscopy a powerful tool for identifying and quantifying chemical substances. Energy Absorption: When an atom or molecule absorbs light, the energy from the light excites the electrons to a higher energy state (a higher orbital). The amount of light absorbed at a particular wavelength depends on: • The concentration of the substance in the sample. • The absorption characteristics of the substance at that wavelength. • Path length (the distance the light travels through the sample).
- 6. Beer-Lambert Law The relationship between the absorption of light and the concentration of a substance is described by the Beer-Lambert Law, which is a fundamental equation in absorption spectroscopy. The law states that: A=ε⋅c⋅lA = varepsilon cdot c cdot lA=ε⋅c⋅l Where: • A is the absorbance (unitless), which is a measure of how much light is absorbed by the sample. • ε is the molar absorptivity or molar absorption coefficient (L·mol⁻¹·cm⁻¹), which is a constant for each substance at a particular wavelength. • c is the concentration of the substance (mol/L). • l is the path length (cm), which is the distance the light travels through the sample. This equation shows that absorbance is directly proportional to the concentration of the absorbing species and the path length through which the light passes.
- 7. Types of Absorption Spectroscopy UV-Vis Absorption Spectroscopy Infrared (IR) Absorption Spectroscopy X-ray Absorption Spectroscopy (XAS) Applications of Absorption Spectroscopy Chemical Analysis: Absorption spectroscopy is frequently used to determine the concentration of specific compounds in a mixture. By measuring the absorbance at specific wavelengths, the concentration of the analyte can be calculated using the Beer- Lambert Law. Environmental Analysis: Absorption spectroscopy is used to detect pollutants, such as heavy metals (e.g., lead, mercury), in air, water, and soil samples. Food and Beverage Industry: Absorption spectroscopy is used to analyze the composition of food products, such as determining the concentration of nutrients or contaminants in food samples.
- 8. SCATTERING Scattering spectroscopy is an analytical technique that measures the scattering of light by a sample. It is based on the interaction of light with matter, where the light is redirected by the sample, often due to the sample's size, shape, or molecular composition. Unlike absorption or emission spectroscopy, where light is either absorbed or emitted by the sample, scattering spectroscopy focuses on the changes in the direction (and sometimes the energy) of the incident light. Scattering occurs when light interacts with the particles, molecules, or atoms in a sample, causing the light to deviate from its original path. By analyzing the scattered light, scattering spectroscopy can provide valuable information about the sample's properties, such as its size, structure, and composition. This technique is widely used in fields like material science, biology, chemistry, and environmental science.
- 9. Types of Scattering Rayleigh Scattering Mie Scattering Raman Scattering Applications of Scattering Spectroscopy Material Science: Scattering techniques like dynamic light scattering (DLS) and Raman spectroscopy are used to characterize the size, shape, and structure of materials at the nanoscale, such as nanoparticles, polymers, and thin films. Environmental Science: Scattering spectroscopy is used to study the properties of aerosols, particulate matter, and pollutants in the atmosphere. Techniques like Rayleigh scattering and Mie scattering help monitor air quality and climate conditions. Nanotechnology: Scattering techniques are important in the study of nanomaterials. DLS and Raman spectroscopy are used to characterize nanoparticles, nanotubes, and other nanostructures for applications in electronics, energy, and medicine.
- 10. REFERENCES Chaswal G.R Anand S.K Instrumental Methods Of Chemical Analysis Himalya Publishing House. Gurumani N. (2021) research methodology biological science.MJP publishers.