How can spectra be used in chemical analysis

As each element has different energy states available to it, each element releases photons of different color when its atoms return to their lower energy states. Since each atom has many excited states high energy levels available to it, several colors of light can be emitted by each element.

The basic principle shared by all spectroscopic techniques is to shine a beam of electromagnetic radiation onto a sample, and observe how it responds to such a stimulus. Spectroscopy , study of the absorption and emission of light and other radiation by matter, as related to the dependence of these processes on the wavelength of the radiation.

Some of the different types of spectroscopy that will be discussed in this article include X-ray spectroscopy, flame spectroscopy, atomic emission spectroscopy AE , atomic absorption spectroscopy AA , spark emission spectroscopy, visible and ultraviolet UV spectroscopy, infared IR and near infared NIR.

Colorimetry, in which a sample absorbs visible light, is one example of a spectroscopic method of analysis.

At the end of the nineteenth century, spectroscopy was limited to the absorption, emission, and scattering of visible, ultraviolet, and infrared electromagnetic radiation. Spectrometric techniques are used to measure the interaction of different frequency components of electromagnetic radiations EMR with that of matter. After interaction with matter, these radiations are absorbed by the matter. When electromagnetic radiation is passed through a prism or grating it is split up and forms a collection of lines representing different wavelengths.

The science of spectroscopy is quite sophisticated. From spectral lines astronomers can determine not only the element, but the temperature and density of that element in the star. The spectral line also can tell us about any magnetic field of the star. The width of the line can tell us how fast the material is moving. We can learn about winds in stars from this. If the lines shift back and forth we can learn that the star may be orbiting another star.

We can estimate the mass and size of the star from this. If the lines grow and fade in strength we can learn about the physical changes in the star. Spectral information can also tell us about material around stars. This material may be falling onto the star from a doughnut-shaped disk around the star called an accretion disk. These disks often form around a neutron star or black hole.

The light from the stuff between the stars allows astronomers to study the interstellar medium ISM. This tells us what type of stuff fills the space between the stars. Space is not empty! There is lots of gas and dust between the stars. Each jump corresponds to a particular wavelength of light. There are many possible electron transitions for each atom.

Each transition has a specific energy difference. This collection of transitions makes up an emission spectrum. These emission spectra are as distinctive to each element as fingerprints are to people. Thus, scientists can use atomic spectra to identify the elements in them.

You can view the atomic spectrum of each element at. Here is a look at emission colors of light produced by four different elements. Video from: Noel Pauller. This video show uses diffraction grating to show the emission spectra of several elements including hydrogen, oxygen, neon and nitrogen.

Use of a tool such as a spectroscope would allow someone to determine the different wavelengths each of these elements is giving off. The color you observe in the video is the sum total of all of the visible emissions from each element.