Spectroscopy
What is spectroscopy?
Spectroscopy is the study of how electromagnetic radiation interacts with matter. Electromagnetic radiation includes gamma rays, X-rays, ultraviolet (UV), visible (vis) and infrared light, as well as longer wavelength microwaves, television waves, and radio waves (Figure 1).
Figure 1
A UV-vis spectrophotometer is a research instrument used to gather information about a chemical sample. A spectrophotometer produces a source of electromagnetic radiation (light) that shines on a chemical sample. It exposes a chemical solution to the ultraviolet and visible region of the electromagnetic spectrum. When the light interacts with the chemical sample, it produces changes in the sample. Depending on the type of chemical, a certain amount of the light gets absorbed by the chemical, which causes electrons to move to a higher energy level. These changes in the chemical are recorded as spectra. The amount of light that reaches the detector is then recorded as a spectrum as shown in Figure 2.
Figure 2
The spectra created by a spectrophotometer thus gives chemists
information such as the chemical makeup of a particular sample.
Why use spectroscopy in high school?
Each discipline in science has its own crucial tools. Astronomy has the telescope. Biology, the microscope. For chemistry, the spectrometer is that critical, central tool. Spectrometry is used in research labs to analyze compounds across the electromagnetic spectrum. The spectroscopy used here focuses on the visible light spectrum to help students bridge the gap between the visible and the invisible: what they can see and what is happening on the subatomic levels. For some, high school chemistry may be the only opportunity to experience such instruments. For those students who plan to continue their studies in the sciences, this experience will strengthen their preparation and skills for college-level work. In all instances, using spectroscopy requires students to use higher-order thinking skills to interpret and analyze their spectra, then apply their conclusions to more general settings.
Instrument Loans through ICN
The Chemistry Department at the University of Maine currently has two UV-vis spectrophotometer-computer units that can be loaned to high school science departments for use during the school year.