LED Irradiation Systems
Often, for photochemistry, excitation only requires a narrow spectral range. This is typically achieved by using a broad spectral range source, such as a xenon lamp, with optical filters to remove unwanted wavelengths. In some instances, intense irradiation is also required to either increase the rate of a reaction or to monitor small optical density changes.
With recent advancements in the production of intense light emitting diodes (LED), both intense and relatively monochromatic sources are available, eliminating the need for filter arrangements. The use of LEDs greatly simplifies irradiation systems at a vey affordable price.
One example of the use of LEDs in our lab was in the shape control of silver nanoparticles, where the intense LED irradiation was capable of reducing typical irradiation times from weeks to hours. Additionally, the narrow emission spectrum of the LEDs make it possible to obtain high purity silver nanoparticles with the desired optical properties. LEDs are also proving useful in catalysis and spectroscopic studies where intense light and long term stability (no fluctuations in intensity on the time scale of spectroscopic measurements, ns to ms) are required.