One application that is gaining popularity is a fiber coupled LED for NMR Spectroscopy. The set up that most people ask for is a Mic-LED and controller with fiber coupler adapter and a long plastic fiber optic.

This set up can be seen in the “Supporting Info” section of these two papers:

• “Discovery of a Photoinduced Dark Catalytic Cycle Using in Situ LED-NMR Spectroscopy”. September 2018
• “Facile Quantum Yield Determination via NMR Actinometry” March 2018

The last few centimeters of the optical fiber is scraped or sanded to let light leak out the side. The fiberoptic is sheaved inside of a clear plastic sheath which inserted into a larger tube with the compounds being analyzed. The fiber optic assembly is inserted into the magnet bore.

The popular wavelengths are 445nm and 365nm.

The advantage of this set up is that LEDs with different wavelengths can be used with the same controller and fiber adapter. Additional LED heads cost just $752. 

Other configuration with higher power or lower cost can be considered, but most customers prefer to duplicate the configuration used in the published paper.

You can see this popular configuration here.