An ultraviolet visible spectrometer helped NASA find water on the moon in 2009. You can also use a UV-Vis spectrometer to determine a substance's chemical composition. Although these measuring devices have numerous advantages, it helps to know about the disadvantages before you discover them while trying to create or analyze a spectrum.
Anatomy of a Spectrum
White light separates into a spectrum when you project it through a slit or prism. Colors at the spectrum's low end have lower energy than those at the high end where violet resides. Move past violet on the spectrum and you enter the world of invisible electromagnetic radiation -- there you find ultraviolet and other forms of high-energy light that you cannot see. Ultraviolet radiation strikes you every time you stand in the sun, and UV blockers help protect you from its damaging effects.
The Discerning Power of UV-Vis Spectroscopy
UV-Vis spectrometers use visible light and ultraviolet radiation to analyze a substance's chemical structure. Spectrophotometers, special types of spectrometers, measure the intensity of light as it varies with wavelength. When Ultraviolet-Visible energy strikes many organic compounds, those compounds absorb it. You can then use a UV-Vis spectrometer to examine a compound and learn information about its molecular structure.
UV-Vis Spectrometer Advantages
UV-Vis spectrometers are valuable because they can analyze substances quickly and they are not difficult to use. In astronomy, they help scientists analyze galaxies, neutron stars and other celestial objects. A spectrum can provide valuable information about an astronomical object, its velocity and the elements it contains. UV-Vis spectrometers bring high-tech spectral analysis to the food industry, where they help laboratory technicians study food products. You'll also find people using these devices in fields as diverse as forensic analysis, research and medicine.
Single-beam devices require you to measure a baseline sample before analyzing another sample. A split double-beam spectrometer enables you to monitor the reference sample while you observe the one you wish to analyze. These types of units are more accurate and beneficial because you don't have to re calibrate them a you do when using a single beam spectrometer.
UV-VIs Spectroscopy Disadvantages
When dust or grim coats mirrors in a double-beam UV-Vis spectrometer, the device's performance degrades. Repair costs can also double because you can't replace one mirror if it needs fixing. Because they work as a pair, you must replace both mirrors. Stray light caused by faulty equipment design and other factors could decrease an instrument's linearity range and reduce the absorbency of the substance it measures. Electronic components in the spectrometer or sample source may also generate noise that decreases measurement accuracy and reduces the device's sensitivity.
- Phys.Org: LCROSS Impact Finds Water on the Moon
- NASA: Lcross
- Chemistry - Principles and Applications; Victor A. Gault, Neville H. McClenaghan
- Encyclopedia of Forensic Science; Suzanne Bell
- Select Science: UV/Vis Spectroscopy Buying Guide
- Food Analysis; S. Suzanne Nielsen
- Cole-Parmer: Seeing the Light - An Overview of Visible and UV-VIS Spectroscopy
- Michigan State University Department of Chemistry: UV-Visible Spectroscopy
- Calibration & Validation Group: Performance of UV-Vis spectrophotometers
- NASA Imagine the Universe: Introduction to Spectroscopy
- Photo Credit GYRO PHOTOGRAPHY/amanaimagesRF/amana images/Getty Images
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