Cari Coleman's Quite Short Stories Et Cetera Blog: Definition of a Spectrometer

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By Cari Coleman
eHow Contributing Writer

$The electromagnetic spectrum is a vast continuum of ever-lengthening waves. Only a fraction is visile to the eye.$

The electromagnetic spectrum is a vast continuum of ever-lengthening waves. Only a fraction is visible to the eye.

Merriam-Webster defines a spectrometer as an instrument that studies how matter interacts with light, measuring a substance's electromagnetic radiation and separating it into its unique color spectrum for analysis.

Etymology

Spectrometer combines the Latin "spectrum"---meaning image or apparition---and the Latin "metrum," or the Greek "metron," both meaning measure.

Spectra

Every substance's molecules emit a unique pattern of light when sufficiently heated. Determined by its atomic makeup, it reveals itself as a band of lines called a line spectrum. Analysis of this spectrum reveals important information about a substance's composition and structure. It is utilized in chemistry, astronomy, medicine and physics.

The Basic Spectrometer

It is housed in a container that blocks all light except that being studied. Light enters through a slit, passing through a collimating lens, turning the light into a beam of parallel light rays. The rays then refract through a prism or grooved mirror---called a grating---that splits the light into its unique spectrum. Another lens focuses the light onto the exit slit, one color at a time. A circular scale records the angle of the prism, which is rotated slowly to reveal the entire spectrum and determine the light's wavelengths.

Types

Each type of spectrometer examines a small portion of the vast electromagnetic spectrum. These are: spectroscopes, which provide visual observation of spectra via telescope; spectrographs, which provide pictographic viewing of spectra via a photographic plate and spectrophotometers, which allow viewing of the visible spectrum by measuring the brightness of each of its colors.

Remembering the Electromagnetic Spectrum

The electromagnetic spectrum consists of Gama rays, X-rays, Ultra-Violet rays, Visible light, Infrared rays, Microwaves and Radio waves. An easy way to remember this is the mnemonic sentence: Grant eXpects Unanimous Votes In Movie Reviews.