Spectroscopy
Spectroscopy identifies substances by how they interact with light.
About this topic
Spectroscopy studies how matter interacts with electromagnetic radiation to identify substances and determine their structure. Main types are UV-visible (electronic transitions), infrared (bond vibrations), NMR (nuclear spins in a magnetic field), atomic absorption and emission (electron transitions in atoms), and mass spectrometry, which actually separates ions by mass.
In infrared spectroscopy, bonds absorb characteristic frequencies: an O−H stretch shows as a broad peak near 3300 cm-1, and a C=O stretch as a sharp peak near 1700, so the functional groups can be recognised. In mass spectrometry, molecules are ionised, accelerated and deflected; the molecular ion peak gives the molar mass and fragments help piece together the structure. NMR reveals the number and environment of hydrogen atoms in a molecule, and MRI scanners use the same principle. UV-visible spectroscopy follows the Beer-Lambert law: absorbance is proportional to concentration, so it can find the concentration of coloured solutions.
Applications include checking drug purity, forensic analysis, water testing, identifying elements in distant stars and monitoring pollutants. A chemist often combines several techniques to solve an unknown, like detective clues.
A misconception is that spectroscopy uses only visible light; it spans the whole electromagnetic spectrum. Another is that mass spectrometry is based on light; it uses electric and magnetic fields to separate ions.
Key ideas
- UV-vis, IR and mass spectrometry
- Spectra act as fingerprints
- Used in forensics and astronomy
Quick check
Use cases: where Spectroscopy helps
- Homework: review the key idea behind Spectroscopy before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Spectroscopy without notes.
- Visual learning: play with the interactive lab to see how Spectroscopy changes when you adjust its inputs.
- Teaching a friend: explain Spectroscopy in your own words, then compare your version with the key ideas.
Chemistry explains medicine, food, cleaning products, fuels and building materials.
Frequently asked questions
What is Spectroscopy?
Spectroscopy identifies substances by how they interact with light.
What will I learn in Spectroscopy?
UV-vis, IR and mass spectrometry. Spectra act as fingerprints. Used in forensics and astronomy.
Is Spectroscopy part of Chemistry?
Yes. It is one of 150 Chemistry topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Spectroscopy lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Spectroscopy?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.