DIY: Fluorescence at home

An easy-to-make substance that glows in UV light

Safe­ty pre­cau­tions

Con­duct the ex­per­i­ment only un­der adult su­per­vi­sion.

Equip­ment

  • 1 tsp urea;
  • 1 tsp cit­ric acid;
  • alu­minum cup;
  • burn­er;
  • can­dle;
  • wood­en stick;
  • con­tain­er of wa­ter.

Step-by-step in­struc­tions

Trans­fer 1 tsp car­bamide to an alu­minum cup and place on a burn­er. Add 1 tsp cit­ric acid and heat. When heat­ed, the crys­tals of urea and cit­ric acid melt. Con­tin­ue heat­ing un­til the mix­ture ac­quires a yel­low­ish-brown col­or. Cool the re­sult­ing mix­ture and dis­solve in wa­ter. The aque­ous so­lu­tion glows blue un­der UV light.

Process de­scrip­tion

Noth­ing will hap­pen if you dis­solve a mix­ture of urea and cit­ric acid in wa­ter and shine a UV light on it. How­ev­er, if the cit­ric acid and urea are fused to­geth­er first, and the re­sult­ing melt is then dis­solved in wa­ter, it will glow blue un­der UV light. When heat­ed to­geth­er, these sub­stances form some cit­razinic acid, which is what “il­lu­mi­nates” the so­lu­tion un­der the UV waves. Such lu­mi­nes­cence is called flu­o­res­cence – the rapid emis­sion of light en­er­gy fol­low­ing a sub­stance’s ab­sorp­tion of light or oth­er elec­tro­mag­net­ic ra­di­a­tion.

Try it