Lecture

Optical absorption measurements

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In course

ME-301: Measurement techniques

Theoretical and practical course on experimental techniques for observation and measurement of physical variables such as force, strain, temperature, flow velocity, structural deformation and vibrations, etc. ...

Description

This lecture on Optical absorption measurements covers the theory, implementation, and applications of optical absorption. It explains how light interacts with charged species like protons and electrons, leading to absorption. The lecture delves into the measurement techniques, such as measuring the number of photons not absorbed, applications in sight, biological cells, chemical reactions, and solar cell potential. It also discusses the limitations of experiments, equipment required for accurate measurements, and the Beer-Lambert Law. The lecture explores topics like identifying chemicals in solutions, monitoring chemical reactions quantitatively, calculating material thicknesses, and measuring absorption for maximum solar cell efficiency.

Instructors (2)

Karen Ann J Mulleners

Expertise experimental fluid dynamics, unsteady aerodynamics, vortex dynamics, flow separation Karen Mulleners is an associate professor in the institute of mechanical engineering in the school of engineering at EPFL. She is the head of the unsteady flow diagnostics laboratory (UNFoLD). She is an experimental fluid dynamicist who focuses on unfolding the origin and development of unsteady flow separation and vortex formation. Karen studied physics in Belgium (Hasselt University, previously Limburgs Universi

Kossi Agbeviade

Official source

Ontological neighbourhood

Chemistry

Physical chemistry: Spectroscopy

Energy engineering

Solar power: Topics in solar power

Related concepts (32)

Thin-film solar cell

Thin-film solar cells are made by depositing one or more thin layers (thin films or TFs) of photovoltaic material onto a substrate, such as glass, plastic or metal. Thin-film solar cells are typically a few nanometers (nm) to a few microns (μm) thick–much thinner than the wafers used in conventional crystalline silicon (c-Si) based solar cells, which can be up to 200 μm thick. Thin-film solar cells are commercially used in several technologies, including cadmium telluride (CdTe), copper indium gallium diselenide (CIGS), and amorphous thin-film silicon (a-Si, TF-Si).

Absorption spectroscopy

Absorption spectroscopy refers to spectroscopic techniques that measure the absorption of electromagnetic radiation, as a function of frequency or wavelength, due to its interaction with a sample. The sample absorbs energy, i.e., photons, from the radiating field. The intensity of the absorption varies as a function of frequency, and this variation is the absorption spectrum. Absorption spectroscopy is performed across the electromagnetic spectrum.

Solar-cell efficiency

Solar-cell efficiency refers to the portion of energy in the form of sunlight that can be converted via photovoltaics into electricity by the solar cell. The efficiency of the solar cells used in a photovoltaic system, in combination with latitude and climate, determines the annual energy output of the system. For example, a solar panel with 20% efficiency and an area of 1 m2 will produce 200 kWh/yr at Standard Test Conditions if exposed to the Standard Test Condition solar irradiance value of 1000 W/m2 for 2.

Electromagnetic absorption by water

The absorption of electromagnetic radiation by water depends on the state of the water. The absorption in the gas phase occurs in three regions of the spectrum. Rotational transitions are responsible for absorption in the microwave and far-infrared, vibrational transitions in the mid-infrared and near-infrared. Vibrational bands have rotational fine structure. Electronic transitions occur in the vacuum ultraviolet regions. Liquid water has no rotational spectrum but does absorb in the microwave region.

Spectrometer

A spectrometer (spɛkˈtrɒmɪtər) is a scientific instrument used to separate and measure spectral components of a physical phenomenon. Spectrometer is a broad term often used to describe instruments that measure a continuous variable of a phenomenon where the spectral components are somehow mixed. In visible light a spectrometer can separate white light and measure individual narrow bands of color, called a spectrum. A mass spectrometer measures the spectrum of the masses of the atoms or molecules present in a gas.

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