Name: uv-vis spectroscopy for light absorption
Uploaded: 2024-12-05T18:32:04.000Z
Duration: 1 min 2 s
Channel: JoVE

K12 Standards

Pennsylvania State Academic Standards

9-12

Earth and Space Science

Space Systems

3.3.9-12.C

ultraviolet-and-visible-uvvis-spectroscopy-overview

Ultraviolet and Visible (UV&ndash;Vis) Spectroscopy: Overview

Ultraviolet and visible spectroscopy is mainly used to identify compounds with conjugated double bonds.
When light passes through a particle, it will absorb either ultraviolet or visible light based on the energy required for transitioning electrons from the initial or ground state to a higher energy excited state.
The ultraviolet or UV spectrum is obtained if the molecule absorbs light between the wavelengths of 180 to 400 nanometers, whereas a visible spectrum is obtained if the absorption occurs between 400 to 780 nanometers.
Since the energy of the radiation is inversely proportional to wavelength, ultraviolet radiation with shorter wavelengths have greater energy than visible light.
UV and visible spectroscopy are used to identify compounds in quantitative analysis by comparing their absorbance values with those of known compounds.

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

Ultraviolet&#8211;visible (UV&#8211;visible or UV&#8211;Vis) spectroscopy is an analytical technique that investigates the interaction between matter and UV&#8211;Vis light within the electromagnetic spectrum. This method is widely used for its versatility, simplicity, and relatively quick data acquisition, making it valuable for both qualitative and quantitative analysis. When UV&#8211;Vis radiation passes through a material,&#160; molecules absorb light depending on the energy required for electronic transitions. As a result of energy absorption, atoms or molecules pass from the ground state to an excited state or higher energy state. If a molecule absorbs UV light, a UV spectrum is generated; if it absorbs visible light, a visible spectrum is produced.
When continuous radiation is transmitted through a material, some wavelengths are absorbed by the molecules, resulting in a decrease in the intensity of transmitted light. This selective absorption leads to the formation of an absorption spectrum that displays peaks corresponding to specific wavelengths absorbed by a molecule. The UV wavelength range of light is from 180 to 400 nanometers, as visible light has a wavelength ranging from 400 to 780 nanometers.&#160; This spectrum, which displays gaps corresponding to absorbed wavelengths, reveals information about the molecule&#39;s chemical structure.
In qualitative analysis, UV&#8211;Vis can be used to identify functional groups or confirm the identity of a compound by matching its absorbance to the absorbance of a known compound. Compared to other spectroscopy techniques, such as fluorescence, which has a higher sensitivity, UV&#8211;Vis is moderately sensitive but widely accessible due to its straightforward instrumentation and ease of use. UV&#8211;Vis instruments typically consist of components such as a light source, sample holder, monochromator or filter for wavelength selection, and detector. The path length, or the distance light travels through the sample, is an important factor in absorbance measurements, as it affects the amount of light absorbed. However, UV&#8211;Vis does have a similar sensitivity to other absorbance measurements, such as infrared spectroscopy.

Ultraviolet&#8211;visible (UV&#8211;visible or UV&#8211;Vis) spectroscopy is an analytical technique that investigates the interaction between matter and ...

Education

JoVE Core

Analytical Chemistry

Unit 1

Introduction to Molecular Spectroscopy

KEY TERMS AND CONCEPTS

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 light, a UV spectrum is produced. If it absorbs visible light, a visible spectrum is produced.

As continuous radiation travels through a material, some wavelengths are absorbed and the transmitted light becomes weaker. This selective absorption creates an absorption spectrum with peaks at the wavelengths a molecule absorbs. The missing parts of the spectrum can reveal information about chemical structure. UV light ranges from 180 to 400 nanometers, and visible light ranges from 400 to 780 nanometers.

In qualitative analysis, UV-Vis spectroscopy can help identify functional groups or confirm a compound’s identity by comparing its absorbance with that of a known compound. The method is moderately sensitive, while fluorescence is more sensitive. Even so, UV-Vis is widely used because its instruments are straightforward and easy to operate. A typical UV-Vis instrument includes a light source, a sample holder, a monochromator or filter for choosing wavelength, and a detector. The path length, or the distance light travels through the sample, also affects absorbance measurements. Its sensitivity is similar to other absorbance methods, such as infrared spectroscopy.

UV-Vis Spectroscopy for Light Absorption

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...

interaction of em radiation with matter: spectroscopy

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

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...

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...

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 UV-Vis spectroscopy measures light absorption, forms absorption spectra, and helps identify compounds using simple, fast instrument setups.

UV-Vis Spectroscopy for Light Absorption | 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.

Physical Science

Waves and Electromagnetic Radiation

3.2.9-12.X

Louisiana Student Standards for Science

High School

Chemistry

motion-and-stability-forces-and-interactions

Motion And Stability: Forces And Interactions

HS-PS2-6

Virginia  Standards of Learning

HIgh School

PS.7

PS.7.b

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

South Carolina College and Career Ready Science Standards

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

Waves and Their Applications in Technologies for Information Transfer

C-PS4-4

the-principle-of-superposition-and-the-gravitational-field

The Principle of Superposition and the Gravitational Field

The principle of superposition applies to gravitational forces of objects that are sufficiently far apart. It states that the net gravitational force on a ...

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Escape Velocity

The escape velocity of an object is defined as the minimum initial velocity that it requires to escape the surface of another object to which it is ...

circular-orbits-and-critical-velocity-for-satellites

Circular Orbits and Critical Velocity for Satellites

The Moon orbits around the Earth. In turn, the Earth (and other planets) orbit the Sun. The space directly above our atmosphere is filled with artificial ...

energy-of-a-satellite-in-a-circular-orbit

Energy of a Satellite in a Circular Orbit

Thousands of artificial satellites orbit the Earth every day at various distances from the Earth. Satellites that orbit the Earth below an altitude of ...

Kepler's First Law of Planetary Motion

In the early 17th century, German astronomer and mathematician Johannes Kepler postulated three laws for the motion of planets in the solar system. He ...

Kepler's Second Law of Planetary Motion

In the early 17th century, German astronomer and mathematician Johannes Kepler postulated three laws for the motion of planets in the solar system. His ...

Kepler's Third Law of Planetary Motion

In the early 17th century, German astronomer and mathematician Johannes Kepler postulated three laws for the motion of planets in the solar system. In ...

Nuclear Fusion

The process of converting very light nuclei into heavier nuclei is also accompanied by the conversion of mass into large amounts of energy, a process ...

Nuclear Power

Controlled nuclear fission reactions are used to generate electricity. Any nuclear reactor that produces power via the fission of uranium or plutonium by ...

Nuclear Fission

Many heavier elements with smaller binding energies per nucleon can decompose into more stable elements that have intermediate mass numbers and larger ...

Nuclear Transmutation

Nuclear transmutation is the conversion of one nuclide into another. It can occur by the radioactive decay of a nucleus, or the reaction of a nucleus with ...

Atomic Structure

All matter is composed of atoms, the smallest individual units of elements. Each atom is made up of three subatomic particles: protons, neutrons, and ...

Radioactivity and Nuclear Equations

Nuclear chemistry is the study of reactions that involve changes in nuclear structure. The nucleus of an atom is composed of protons and, except for ...

Nuclear Stability

Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10&#8722;15 meters, a nucleus is ...

Students who demonstrate understanding can develop a model based on evidence to illustrate the life span of the sun and the role of nuclear fusion in the sun's core to release energy in the form of radiation.  Clarification Statement: Emphasis is on the energy transfer mechanisms that allow energy from nuclear fusion in the sun's core to reach Earth.  Examples of evidence for the model include observations of the masses and lifetimes of other stars, as well as the ways that the sun's radiation varies due to sudden solar flares ("space weather"), the 11-year sunspot cycle, and non-cyclic variations over centuries.  Assessment Boundary: Assessment does not include details of the atomic and sub-atomic processes involved with the sun's nuclear fusion.

3.3.9-12.A

Emission Spectra

When solids, liquids, or condensed gases are heated sufficiently, they radiate some of the excess energy as light. Photons produced in this manner have a ...

atomic-spectroscopy-absorption-emission-and-fluorescence

Atomic Spectroscopy: Absorption, Emission, and Fluorescence

Atomic spectroscopy is a vital tool in elemental analysis, both qualitatively and quantitatively. It can be broadly divided into optical spectroscopy, ...

Detection of Black Holes

Although black holes were theoretically postulated in the 1920s, they remained outside the domain of observational astronomy until the 1970s.
Their ...

space-time-curvature-and-the-general-theory-of-relativity

Space-Time Curvature and the General Theory of Relativity

In 1905, Albert Einstein published his special theory of relativity. According to this theory, no matter in the universe can attain a speed greater than ...

Schwarzschild Radius and Event Horizon

No object with a finite mass can travel faster than the speed of light in a vacuum. This fact has an interesting consequence in the domain of extremely ...

The Wave Nature of Light

The nature of light has been a subject of inquiry since antiquity. In the seventeenth century, Isaac Newton performed experiments with lenses and prisms ...

Nuclear Binding Energy

The difference between the calculated and experimentally measured masses is known as the mass defect of the atom. In the case of helium-4, the mass defect ...

Metal Flame Emission

Metal Flame Emission
Flame testing is an analytical technique where a sample is placed in a flame, and the characteristic flame color is used to identify ...

Molecular Spectroscopy: Absorption and Emission

Molecules possess discrete energy levels called quantum states. Unlike atoms, which have simpler energy levels, molecules possess additional rotational ...

atomic-emission-spectroscopy-instrumentation

Atomic Emission Spectroscopy: Instrumentation

The instrumentation of atomic emission spectrometry (AES) involves various components, including atomization devices that convert samples into gas-phase ...

atomic-absorption-spectroscopy-radiation-and-light-sources

Atomic Absorption Spectroscopy: Radiation and Light Sources

Atomic absorption spectroscopy (AAS) relies on the Beer-Lambert law, which requires that the radiation source emits a narrow range of wavelengths to match ...

Students who demonstrate understanding can construct an explanation of the Big Bang theory based on astronomical evidence of light spectra, motion of distant galaxies, and composition of matter in the universe.  Clarification Statement: Emphasis is on the astronomical evidence of the red shift of light from galaxies as an indication that the universe is currently expanding, the cosmic microwave background as the remnant radiation from the Big Bang, and the observed composition of ordinary matter of the universe, primarily found in stars and interstellar gases (from the spectra of electromagnetic radiation from stars), which matches that predicted by the Big Bang theory (3/4 hydrogen and 1/4 helium).  Assessment Boundary:

3.3.9-12.B

Spectrophotometry: Introduction

Spectrophotometry is the quantitative measurement of the absorption, reflection, diffraction, or transmission of electromagnetic radiation through a ...

Atomic Emission Spectroscopy: Overview

Atomic emission spectroscopy (AES) is an analytical technique used to determine the elemental composition of a sample by analyzing the light emitted from ...

Atomic Emission Spectroscopy: Lab

AES is a powerful analytical technique, especially effective when used with plasma sources, producing abundant spectra in characteristic emission lines. ...

Flame Photometry: Overview

Flame photometry, also known as flame emission spectrometry, is a technique used for the qualitative and quantitative analysis of elements present in a ...

The Greek philosopher Democritus proposed that everything on Earth is made up of tiny particles called atomos, Greek for &#34;indivisible,&#34; from which ...

Students who demonstrate understanding can communicate scientific ideas about the way stars, over their life cycle, produce elements.  Clarification Statement: Emphasis is on the way nucleosynthesis, and therefore the different elements created, varies as a function of the mass of a star and the stage of its lifetime.  Assessment Boundary: Details of the many different nucleosynthesis pathways for stars of differing masses are not assessed.

Tidal Forces

The origin of Earth&#39;s ocean tides has been a subject of continuous investigation for over 2000 years. However, the work of Newton is considered to be ...

Students who demonstrate understanding can use mathematical or computational representations to predict the motion of orbiting objects in the solar system.  Clarification Statement: Emphasis is on Newtonian gravitational laws governing orbital motions, which apply to human-made satellites as well as planets and moons.  Assessment Boundary: Mathematical representations for the gravitational attraction of bodies and Kepler's Laws of orbital motions should not deal with more than two bodies, nor involve calculus.

3.3.9-12.D

UV-Vis Spectroscopy for Light Absorption

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