LEDs in the ranges Stan specifies (visual range, and specifically red) do not have small enough wavelengths to ionize anything individually, however they do add energy to the atoms, as photon/light/laser energy, and move the electrons farther from the nucleus, up to the maximum absorbed rate, this makes it *easier* for the voltage to pull off the electrons, but the LEDs themselves are not powerful enough to do anything. (To ionize with LEDs alone you would need to go into the deep-ultra-violet range with a wavelength of around 100 nm or so, and these things are expensive to rare to non-existent)
Get a working VIC then you can add LEDs to make the process more efficient!
Heating Hydroen with the right Wave Length... Hrm...
How about Heating Air with the correct wave length... What leds would be good use for heating Air? LOL, Well, its quite like this,, You can put air in a metal cylinder and heat that cylinder, That air will become heated just as hydrogen would become heated. When an atom becomes ionized, Talking on the atomic level the electron moves away from the nucleus! Just as the Oxygen electron moved away from the nucleus when the oxygen was placed in the metal heated cylinder. Heat causes this effect. You can simply use the right "Wave Length" of led to move the hydrogens electron away from its nuc, Or, you can do it the simple way and use a heat source. Both techniquies will cause the electron to move and both will move the electron. In Fact, When you say use a led to cause ionization of an atom instead of using heat, "Its like you're reinventing the wheel." Lots of folks Simply Can not compute those facts, But its very basic knowledge that can be very easily understood.
Heated Atoms get bigger in mass, Causing the electrons to move outward. Depending on how far the electron moved outward determins that atoms Nanameter wavelength due to the Frequency at which the electron orbits the nucleus. Use the proper led, or heat source the atom will react the same no matter the source used. However, (If you are trying to use a Led Photo,) You had better hit that resonate freq which causes the electron to move outward.. Or Simply put... Chunk the led in the garbadge an heat it some other way and forget all about the nanometer. Thats way to technical and it is by no means neccaserry required to get the job done. Google how the electrons Distance from the nucleus is used to Determine how hot the atom is. There comes a time of ionization. Learn exactly what that means when it comes to the electron. Its simple. To Create Water Gas using water and coal ionization is also a must. Look in that area as well.
Thats just my off topic post, Hopefully stevie want get to angry with me. I'll send him a beer, Cheers.