Tritium is indeed the best stuff - BUT - tritium is an isoptope of hydrogen and is a gas, not a liquid. The "tritium" night sights used on firearms (bows now, too, and even some fishing lures) are actually non-hydrogen-pemeable glass or thermoplastic vials of the gas with a phosphor coating inside the vial. Yes - even the tiniest of dots. I use them too. Trivia: Tritium is also the radioactive gas used as one of the triggers compressed to start a thermonuclear "hydrogen" bomb reaction. The other is deuterium. Both are required to finish off the earth in one pop.
Tritium would not be safe to use by itself, it is radioactive and toxic, and being a gas, kinda gets away from you quickly!
HOWEVER - I have successfully used some short-term GITD paint made by good old Krylon for a variety of projects. Called Krylon "Glowz" it produces the same eery green-white color that lasts a few hours after a few hours of exposure to daylight or regular commercial fluorescent lighting. Both brush-on and spray. Not very expensive - I got mine at Home Depot I think.
Krylon: Products: Glowz® Brush-On
It's a latex paint, water soluble, and I recommend you use it over a base coat of flat white primer, preferably something with a solvent base like acrylic or lacquer.
One of my great feats with this stuff was to paint stars and planets and rockets and such on the latex white ceiling of my son's bedroom when he was a wee lad. Endless entertainment, and now that he is in his teens he won't let me get rid of it! Few hours with the drapes open or a fluorescent ceiling light on and outer space glows for a couple hours. Been working fine for over ten years.
If you're in need you can overcoat the Glowz with a clear sealer so it is more weatherproof/waterproof.
Not authentic but may get you where you want to go and if it isn't right you can remove it fairly easily with denatured alcohol.