Spectroscopy is the study of how radiated matter and energy interact. The matter absorbs energy, creating an excited state. When the matter is metal, it’s easy to see the interaction because there’s visible evidence, like sparks, created by the electromagnetic waves that form the visible light on the visible spectrum.

Spectrometry, on the other hand, deals with measuring specific spectrums. It is the application of spectroscopy that creates the results that can be assessed. Spectroscopy alone studies the energy and matter to determine the interaction but does not create results, so the two go hand-in-hand. You need spectrometry to analyze and interpret spectroscopy. Spectrophotometry is a method of measuring how much light a chemical substance absorbs.

Spectroscopy studies the absorption and emission of light by matter, and has expanded to include interactions between electrons, protons, and ions. Multiple scientific fields including chemistry, physics, and astronomy have grown as a result of spectroscopy.

What is a Spectrometer?

A spectrometer is any instrument used to measure the variation of a physical characteristic over a spectrum. These tools are used to collect information about a material based on the amount of infrared, visible, or ultraviolet light it projects. Astronomers use spectrometers to determine the temperature of space objects, determine the speed at which those objects are traveling, and estimate the objects’ weight. They can also be used to determine the composition of items, including the elemental components. Those in the medical field use spectrometers to find toxins and contaminants in the bloodstream, and may also find disease markers.

Types of Spectroscopy

  • Absorption Spectroscopy: With this method of spectroscopy, light is absorbed with respect to the wavelength. The sample molecules are excited to a higher energy state once they absorb the light. The amount of excitation is directly proportional to the wavelength of the light.
  • Infrared Spectroscopy: This type of spectroscopy measures the vibrations of the interatomic bonds of a sample. They are measured at different frequencies when the sample is exposed to infrared light. The spectrometers can also be used to measure the number of absorbing molecules.
  • X-Ray Spectroscopy: With X-ray spectroscopy, the inner electrons of sample molecules are excited, and when those excited electrons fall into the vacancy generated as a result of energy absorption, an x-ray fluorescence emission spectrum is produced.
  • Ultraviolet Spectroscopy: In this type of spectroscopy, the sample is exposed to ultraviolet (UV) light. Once the samples absorb the light energy, the electrons are excited and the absorbance characteristics of the sample are measured based on this excitation. This type of spectroscopy is often used to investigate chemical bonding of molecules.
  • Laser Spectroscopy: Laser spectroscopy uses laser light as a source of radiation. It can be used to measure the interaction of light with sample molecules. This type of spectroscopy has high resolution and high sensitivity. 

Major applications of spectrometers include:

  • Monitoring dissolved oxygen content in marine ecosystems
  • Space exploration
  • Respiratory gas analysis in hospitals
  • Characterization of protein
  • The study of spectral emission lines of distant galaxies.
Spectrometer vs Spectrophotometer explained

What is a Spectrophotometer?

A spectrophotometer refers to a number of instruments that measure light. The exact definition varies depending on the area of science or industry. In all situations, the term “photo” is used to indicate that the spectrometer is used to quantitatively measure light intensity with wavelengths. They can also measure the intensity of electromagnetic radiation at numerous wavelengths.

These tools measure the absorbance of wavelengths of solutions, as well as the transparency or transmittance of solids. They can also measure the reflectance of solutions. Using different calibrations and controls, they can measure the diffusivity of light ranges in the electromagnetic spectrum covering 200 nm to 2500 nm.

Types of Spectrophotometers

There are two basic types of spectrophotometers. The single-beam spectrophotometer measures the relative light intensity before and after the test sample is introduced. The double-beam spectrophotometer compares the intensity of light between a reference light path and the substance being measured. Double beams are not as sensitive to fluctuations in the light source, but single beam options are more compact and have a higher dynamic range. 

Other options include:

  • Atomic Absorption Spectrophotometer
  • Infrared Spectrophotometer
  • Laboratory Colorimeter/Digital Colorimeters
  • Spectrofluorometer
Differences Between a Spectrometer and Spectrophotometer

The Differences Between a Spectrometer and Spectrophotometer

Part of what makes this confusing for a lot of people is that all spectrophotometers incorporate a spectrometer. It’s also true that other analytical instruments use spectrometers. The spectrometer is the part of the spectrophotometer that is most responsible for measuring things. The spectrophotometer is a complete system that includes a light source along with a means to collect the light that has interacted with the things being tested, as well as a spectrometer for measurements.

To use a spectrometer, turn it on and wait about 5 minutes for it to heat. Load a reference substance and calibrate it. A spectrum will be determined for the sample. Then the wavelengths are measured and analyzed. From there, the item you want to study is loaded. Light passes through the machine and readings are made based on the colors and information that is reflected.

To use a spectrophotometer, clean the machine to remove all fingerprints and dirt. Add the solution (not water) to the machine. Set to the desired wavelength and insert the blank cuvette, confirming the arrow is aligned. Calibrate the spectrophotometer by pressing the set 0 button or indicator for the necessary wavelength. Introduce the solution, then calculate its absorbency. 

When shopping for the right spectrophotometer for your lab, it’s important to consider the applications you’ll be using it for in your lab. Because this lab equipment is pricey, many labs and startups opt to lease their spectrophotometers. With a leasing program like the one we offer at Excedr, you get access to the equipment you need at a fraction of the upfront cost to purchase new or refurbished equipment. Not only does this mean you have more control over your budget, but you also won’t have to worry about the cost of maintenance and equipment upkeep, and you can easily upgrade the equipment once the lease is over.