Spectroscopy Facts for Kids

A flame from alcohol and its light spectrum.

Spectroscopy is a way scientists study light to learn about different materials. Imagine light as tiny waves. Spectroscopy looks at these waves after they have been given off, bounced off, or shined through a solid, liquid, or gas.

To find out what a material is made of, scientists often heat it up. Hot things glow, and each chemical glows in its own special way. This glow creates a unique pattern of colors, like a rainbow, called a spectrum. Spectroscopy helps us separate and measure the brightness of these different colors or wavelengths. By doing this, scientists can figure out what chemicals are in a mixture. They can also learn other things, like how hot something is.

Spectroscopy lets scientists explore things too small to see, even with a microscope. This includes tiny molecules and even smaller parts like protons, neutrons, and electrons. Special tools are used to measure and understand these light waves.

How Scientists Use Light to Study Materials
Related Discoveries
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How Scientists Use Light to Study Materials

Scientists use different types of light and special tools to study materials. Each method helps them learn something unique about the chemicals.

Infrared Spectroscopy: Seeing Molecular Vibrations

Infrared spectroscopy uses infrared light, which is a type of light we can't see but can feel as heat. This method is great for finding specific parts of organic molecules, like the building blocks of living things. When organic molecules absorb infrared light, they start to vibrate in unique ways. Each type of vibration is like a special dance move for a molecule. By looking at these "dance moves," scientists can identify different parts of the molecule. The results are shown on a graph that helps scientists understand the molecule's structure.

X-ray Crystallography: Mapping Atomic Structures

X-ray crystallography helps scientists see the exact structure of materials that form crystals. Think of crystals as tiny, perfectly ordered structures, like salt or sugar. This method uses X-rays, which are very powerful light waves. When X-rays hit the atoms in a crystal, they bounce off in a specific pattern. By studying this pattern, scientists can figure out where each atom is located in the crystal. This has been used to map the structure of important things like DNA, proteins, and even metals. The best part is that the sample being studied is not damaged.

Ultraviolet-Visible Spectroscopy: Measuring Chemical Amounts

Ultraviolet–visible spectroscopy uses visible light (the light we can see) and ultraviolet light (another type of light we can't see). This method is used to find out how much of a certain chemical is in a liquid. The color of a liquid often tells us something about its chemical makeup. For example, a blue liquid looks blue because it absorbs other colors of light and reflects blue light. This spectroscopy method works by shining light through a liquid sample and then measuring how much light the liquid absorbs. The more light absorbed, the more of that chemical is present.

Nuclear Magnetic Resonance: Exploring Atomic Nuclei

Nuclear magnetic resonance (NMR) is a powerful method that looks at the tiny centers of atoms, called nuclei. It uses the magnetic properties of certain nuclei, especially those of carbon-13 (¹³C) and hydrogen-1 (¹H). The NMR machine creates a strong magnetic field that makes these nuclei act like tiny magnets. They either line up with the machine's magnetic field or against it.

Next, the nuclei are hit with radio waves. This makes some of the nuclei flip their alignment. When they flip, they release energy, which the machine detects. A computer then turns this information into a graph. This graph helps scientists understand the structure of molecules in great detail. Like X-ray crystallography, NMR does not destroy the sample being studied. Below is a picture of a large NMR system.

Related Discoveries

Images for kids

An example of spectroscopy: a prism analyses white light by dispersing it into its component colors.
A huge diffraction grating at the heart of the ultra-precise ESPRESSO spectrograph.
UVES is a high-resolution spectrograph on the Very Large Telescope.