Modern technology has significantly changed how spectrophotometers perform compared to the early models from many decades past. These devices have become vital in global research, development and production across a broad industry range. Because multiple spectrophotometer types play different roles, choosing the correct device and selecting the optimal settings for each instrument are vital for achieving the most desirable results.
A spectrophotometer consists of two primary elements — a spectrometer and a photometer. A spectrometer is an instrument that supplies light at a specific wavelength, while a photometer measures the light’s intensity. A spectrophotometer is an entire system that contains a light source and the components to collect the light for measurement.
Even though all spectrophotometers contain a spectrometer, not all spectrometers are types of spectrophotometers.
Spectrophotometers determine the absorbance and transmittance properties of various materials as a function of wavelength, calculating the number of photons of reflected or transmitted light. These results show the exact concentration of a colored solution or object.
A spectrophotometer’s other components include a light source, monochromator, sample compartment, detector and display. When the light enters the monochromator, it hits the prism and refracts, separating into its component wavelengths. This light then interacts with the sample and the transmitted or reflected light is collected and quantified.
When using a spectrophotometer, choosing the wavelength ideal for the property you’re measuring is critical. Because composition can vary significantly from one sample to another, optimum wavelengths can vary in size and type, including visible (VIS), ultraviolet (UV) and infrared (IR) wavelengths.
For absorbance, an IR spectrophotometer uses light over the IR range at 700 to 15,000 nanometers. In comparison, a UV-visible device utilizes light over the VIS range at 400 to 700 nanometers and the UV range at 185 to 400 nanometers.
VIS and UV spectroscopy reveal electronic transitions in atoms and molecules. Compounds that absorb only in the UV region are colorless, while ones that absorb in the visible region have color. Wavelengths for blue light range between 400 and 450 nanometers, and wavelengths for red light lie between 700 and 750 nanometers. If the wavelength is less than 400 nanometers, it is UV and has more energy.
An absorbance spectrum is a valuable tool in helping determine which wavelength is most useful. Typically, using a wavelength at maximum absorption provides the best results.
To learn more about spectrophotometers and determine which type is ideal for your application, contact us online today. You can also check out our blog for additional posts about spectrophotometers and color measurements.
Mr. Philips has spent the last 30 years in product development and management, technical sales, marketing, and business development in several industries. Today, he is the global market development manager for HunterLab, focused on understanding customer needs, providing appropriate solutions and education, and helping to solve customer color challenges across these industries and cultures.LinkedIn