Name: em radiation and matter in spectroscopy
Uploaded: 2024-12-05T18:32:03.000Z
Duration: 1 min 12 s
Channel: JoVE

K12 Standards

Pennsylvania State Academic Standards

9-12

Physical Science

Waves and Electromagnetic Radiation

3.2.9-12.X

interaction-of-em-radiation-with-matter-spectroscopy

Interaction of EM Radiation with Matter: Spectroscopy

Spectroscopy is the study of the interaction between electromagnetic radiation and matter.
Here, the electric field component of the radiation can interact with electrical charges in molecules, and the magnetic field component can interact with magnetic dipoles in atoms.
These interactions can be visualized as photons striking atomic particles in matter. Two crucial attributes of EM radiation are intensity and amplitude.
The intensity, or irradiance, of EM radiation is the number of photons striking a given area of a substance within a specific time interval. Intensity is proportional to the square of the amplitude. Amplitude is the height of a wave measured from the midpoint to the peak.
EM radiation may be transmitted through matter without interaction, leading to no change in energy and intensity.
However, a loss in intensity can occur when the radiation interacts with matter and is either reflected back to the source, scattered in different directions, or absorbed by atoms or molecules.

interaction of em radiation with matter: spectroscopy

Electromagnetic (EM) radiation can be considered an oscillating electric and magnetic field propagating through a medium that can interact with matter in its path. The electric field in the radiation can interact with electrical charges in the atoms or molecules in the matter. On the other hand, the magnetic field can interact with the magnetic field in the atomic nucleus. The study of the interaction between electromagnetic radiation and matter is termed spectroscopy. Spectroscopy is the study of how EM radiation interacts with matter, primarily focusing on how substances absorb and emit light. This process reveals unique information about the atomic and molecular structure of the matter involved, providing insight into its chemical composition and properties.
EM radiation can be considered as a wave and a particle simultaneously. It can be characterized by the properties of a wave, such as intensity (I) and amplitude (A). However, its interactions with matter are often thought of in terms of photons, which are elementary particles. Intensity (or irradiance) is the number of photons striking a given matter area during a particular time interval. The amplitude of the wave is the distance between the peak of the wave and the equilibrium point of the wave. The intensity of radiation is directly proportional to the square of its amplitude.
<img alt="Intensity proportionality formula, I &#8733; A&#178;, used in optical studies and light intensity analysis." src="/files/ftp_upload/13023/13023_PT_Figure_1.svg" style="text-align: center; height: 15px;" data-altupdatedat="1761830439000" data-alt="Figure1" />
EM radiation may be transmitted through matter without any interaction. In this case, the intensity and energy of the radiation going into the matter and coming out of the matter will be the same. The interaction between EM radiation and matter can occur in different ways. In some cases, transmission occurs, allowing radiation to pass through matter without alteration, maintaining the same intensity and energy levels upon exit. Reflection and scattering are other interaction types where radiation is directed back to its source or dispersed randomly; the energy may remain unchanged (elastic) or may vary (inelastic). Another significant interaction is absorption, where matter takes up energy from the radiation, resulting in a reduction of the transmitted radiation's intensity. Emission occurs when absorbed energy is later released by the substance, often as light at different wavelengths.
To analyze such interactions, various spectroscopic techniques are used in research and industry, including infrared (IR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and mass spectrometry (MS). Each technique offers a unique window into molecular structure, enabling precise identification of compounds and detailed analysis of complex chemical systems.

Electromagnetic (EM) radiation can be considered an oscillating electric and magnetic field propagating through a medium that can interact with matter in ...

Education

JoVE Core

Analytical Chemistry

Unit 1

Introduction to Molecular Spectroscopy

KEY TERMS AND CONCEPTS

em radiation and matter in spectroscopy

Electromagnetic radiation and matter interact in ways that reveal details about atoms and molecules. In spectroscopy, scientists study how EM radiation is absorbed, emitted, transmitted, reflected, or scattered by a substance. This helps identify its chemical composition and properties.

EM radiation behaves as both a wave and a particle. As a wave, it has intensity and amplitude. Intensity, also called irradiance, is the number of photons that strike a given area in a certain time. Amplitude is the distance from the wave peak to the equilibrium point, and intensity is directly proportional to the square of the amplitude.

Sometimes EM radiation passes through matter without any interaction. In that case, the radiation coming out has the same intensity and energy as the radiation that entered. Reflection and scattering are other forms of interaction. Reflection sends radiation back toward its source, while scattering spreads it in different directions, and either process may be elastic or inelastic.

Absorption and emission are also important in spectroscopy. In absorption, matter takes in energy from the radiation, so the transmitted intensity decreases. In emission, the substance later releases absorbed energy, often as light at different wavelengths. Scientists use techniques such as infrared spectroscopy, ultraviolet-visible spectroscopy, nuclear magnetic resonance spectroscopy, and mass spectrometry to study these interactions and learn about molecular structure.

EM Radiation and Matter in Spectroscopy

dual nature of electromagnetic (em) radiation

dual-nature-of-electromagnetic-em-radiation

EM Spectrum, Waves, and Photon Energy

Electromagnetic radiation has both wave and particle features. It includes electric and magnetic field components that oscillate in planes perpendicular to each other. These fields are also perpendicular to the direction the radiation moves through space. As a wave, electromagnetic radiation is described by wavelength and frequency. Wavelength is the distance between two consecutive peaks or troughs. Frequency is the number of wave cycles that pass a point in a fixed time. The electromagnetic...

Electromagnetic radiation and matter interact in ways that reveal details about atoms and molecules. In spectroscopy, scientists study how EM radiation is absorbed, emitted, transmitted, reflected, or scattered by a substance. This helps identify its chemical composition and properties. EM radiation behaves as both a wave and a particle. As a wave, it has intensity and amplitude. Intensity, also called irradiance, is the number of photons that strike a given area in a certain time. Amplitude...

molecular spectroscopy: absorption and emission

molecular-spectroscopy-absorption-and-emission

Molecular Energy Levels in Spectroscopy

Molecular spectroscopy describes how molecules absorb and emit light by moving between energy levels. These levels are called quantum states. Unlike atoms, molecules also have rotational and vibrational energy levels, so their energy structure is more complex. Each level is separated by an energy gap. The gaps between electronic, vibrational, and rotational levels are very different in size. A diatomic molecule can be used to show these three kinds of energy levels. A molecule can absorb a...

spectrophotometry: introduction

Spectrophotometry for Absorption Spectra

Spectrophotometry measures how a material absorbs, reflects, diffracts, or transmits electromagnetic radiation. It compares the intensity of radiation before and after it interacts with the material. The result shows how the material responds to different wavelengths. A spectrophotometer is the device used for this measurement. It includes a source of electromagnetic radiation, a slot for the sample, and a detector. The detector measures the radiation that leaves the material, including...

ultraviolet and visible (uv&ndash;vis) spectroscopy: overview

ultraviolet-and-visible-uvvis-spectroscopy-overview

UV-Vis Spectroscopy for Light Absorption

UV-Vis spectroscopy measures how materials absorb ultraviolet and visible light. It is a useful analytical method because it is versatile, simple to use, and gives results quickly. Scientists use it for both qualitative and quantitative analysis. When UV-Vis radiation passes through a sample, molecules absorb specific wavelengths based on the energy needed for electronic transitions. This absorption moves atoms or molecules from a ground state to an excited state. If a molecule absorbs UV...

uv&ndash;vis spectroscopy: molecular electronic transitions

uvvis-spectroscopy-molecular-electronic-transitions

UV-Vis Spectroscopy and Molecular Absorption

UV-Vis spectroscopy shows how molecules absorb ultraviolet and visible light. It is used to study electronic structure by tracking how electrons move between molecular orbitals. The absorbed light must match the energy gap between the ground state and an excited state. In this process, an electron moves from the highest occupied molecular orbital, or HOMO, to the lowest unoccupied molecular orbital, or LUMO. This jump raises the electron to a higher energy level. The energy difference between...

uv&ndash;vis spectrometers

UV-Vis Spectrophotometer Parts and Samples

A UV-visible spectrophotometer measures how much UV and visible light a sample absorbs. It uses a light source, a wavelength selector, a sample holder, and a detector to build the spectrum. This makes it useful for checking liquid samples in the lab. The light source depends on the region being measured. A deuterium lamp provides UV radiation, and a tungsten lamp provides visible radiation. A monochromator or prism acts as a diffraction grating and splits the incoming light into different...

uv&ndash;vis spectrum

How Molecular Structure Shapes UV-Vis Bands

UV-Vis spectroscopy shows how a molecule absorbs light in the ultraviolet and visible ranges. When light passes through a substance, some of it is absorbed and the rest is reflected or transmitted. Molecules that absorb between 180 and 400 nm give a UV spectrum, while absorption in the 400 to 780 nm range gives a visible spectrum. A UV-Vis spectrum is a plot of absorbance versus wavelength. The y-axis shows molar absorptivity, ε, or log ε, and the x-axis shows wavelength. Absorbance describes...

uv&ndash;vis spectroscopy: beer&ndash;lambert law

Using Absorbance to Find Concentration

The Beer-Lambert law links absorbance, concentration, and path length in a solution. It is based on ideas from Johann Heinrich Lambert and August Beer. Their work helps explain how light changes as it passes through a medium. Lambert's law says that when light passes through a medium, the loss in intensity is directly proportional to the original intensity and the path length. Beer’s law adds that the transmittance of a solution stays constant if the product of concentration and path length...

photoluminescence: fluorescence and phosphorescence

photoluminescence-fluorescence-and-phosphorescence

Light Emission from Excited Molecules

Photoluminescence is light emission from molecules after they absorb light energy. A substance takes in photons, which raises electrons to excited energy levels. The electrons then relax back to the ground state and release light. This process appears in many materials, including semiconductors, organic compounds, and inorganic compounds. The main role of electron spin helps separate photoluminescence into fluorescence and phosphorescence. In a singlet spin state, two electrons share the same...

variables affecting phosphorescence and fluorescence

variables-affecting-phosphorescence-and-fluorescence

Factors That Change Light Emission in Molecules

Fluorescence and phosphorescence depend on several factors that change how molecules emit light. These effects matter in analytical chemistry, biological imaging, and materials science because they help scientists detect molecular properties and see cellular structures. Molecular structure is one of the main influences. Aromatic compounds with low-energy pi-bonding to pi-non-bonding transitions often give strong fluorescence. Aliphatic and alicyclic carbonyl compounds, as well as highly...

deactivation processes: jablonski diagram

Jablonski Diagram: Light Loss Pathways

Jablonski diagrams show how excited molecules lose energy after absorbing light. They are used to track both light-emitting and non-light-emitting steps in luminescence. The diagram gives a simple picture of the energy states a molecule can move through. The lowest line in a Jablonski diagram is the ground-state energy of the molecule. This state is usually a singlet state, and it represents the condition of most molecules in solution at room temperature. The lines above it show vibrational...

photoluminescence: applications

Fluorescent and Phosphorescent Analysis

Photoluminescence is useful in chemical analysis because it is sensitive and selective. It can support both direct and indirect measurements of an analyte, which is the substance being tested. When an analyte has a strong quantum yield, it can be measured directly by fluorescence or phosphorescence. Indirect analysis is used when the analyte is not naturally fluorescent or phosphorescent, or when its quantum yield is poor. One approach is to react the analyte with a reagent to make a...

fluorescence and phosphorescence: instrumentation

fluorescence-and-phosphorescence-instrumentation

Measuring Fluorescence and Phosphorescence

Fluorometers and spectrofluorometers are instruments used to measure molecular fluorescence. They do this by choosing specific excitation and emission wavelengths. The two instruments use different light sources and wavelength-selection methods. A fluorometer uses absorption interference filters to select the excitation and emission wavelengths. Its excitation source is usually a low-pressure mercury vapor lamp. This lamp gives intense lines across the ultraviolet and visible regions.

key terms and concepts

Learn how electromagnetic radiation interacts with matter through transmission, reflection, scattering, absorption, and emission in spectroscopy.

EM Radiation and Matter in Spectroscopy | JoVE K12

analytical chemistry

JoVE Core Analytical Chemistry simplifies complex chemical principles by breaking them down into clear, engaging animations, making topics from SI Units to NMR spectroscopy more accessible and straightforward. Additionally, the scientist-in-action videos highlight the application of these concepts in real-world research conducted in laboratories globally.

Louisiana Student Standards for Science

High School

Waves And Their Applications

HS-PS4-4

Tennessee Academic Standards

Physics

waves-and-their-applications-in-technologies-for-information-transfer

Waves and Their Applications in Technologies for Information Transfer

PHYS.PS4.6

PHYS.PS4.7

Arizona Science Standards

HS+C.P1

HS+C.P1U1.2

Alabama Course of Study Science

Earth and Space Science

Earth's Place in the Universe

9-12.ESS.1.2

Florida Department of Education

SC.912.P.10

SC.912.P.10.19

Texas Essential Knowledge and Skills

PHYS.8

PHYS.8.E

PHYS.8.F

PHYS.9

PHYS.9.A

south-carolina-college-and-career-ready-science-standards

South Carolina College and Career Ready Science Standards

Chemistry

C-PS4-4

C-PS4-5

P-PS4-4

P-PS4-5

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3.2.9-12.T

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propagation-speed-of-electromagnetic-waves

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3.2.9-12.V

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EM Radiation and Matter in Spectroscopy

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