Near UV LED (around 350nm)

Colleagues,

I'm setting up a fluorescence experiment with quinine as fluorescent dye. Quinine is a common fluorescence standard, that's why I chose it. The caveat with quinine, though, is that its excitation band is in near UV; peak is between 320nm and 370nm. Due to size constraints, I'd like to use LED for excitation. At the moment I don't know the minimum amount of illumination that will be needed.

First, I've looked for LEDs with wavelength peak in the desired range. The LEDs I was able to find are low power – under 1mW. In terms of flux, it's 10s of mlm vs. 1000s of mlm delivered by high power blue LEDs (e.g. Osram Golden Dragon).

Currently, I'm looking for high power visible light LEDs with broad tails extending into UV. Haven't found a suitable one yet.

Any suggestion or insight is really appreciated!

- Nick

For fluoroscopy you would normally pick an LED with its peak as close to the excitation wavelength as possible. The are quite a few specialist UV LED manufacturers - BiVar for example.

The problem with what you are planning to do is you will have a huge amount of light from the LED at the fluorescence wavelength which will ruin your measurement.

You will need some optical filters - both on the LED and detector. It is not unusual for the received signal to be very small.

Keith