Indian scientists have developed a special safety ink that can prevent counterfeiting of banknotes and identity documents.
After exposure to UV light of a certain frequency, the ink shows two colours.
Jagran Josh reports the bi-luminescent safety ink was developed by scientists from the National Physical Laboratory (NPL) of the Council of Scientific and Industrial Research (CSIR) in New Delhi and the Academy of Scientific and Innovative Research in Ghaziabad.
The study is published in the Journal of Materials Chemistry-C.
The ink works as follows:
- Under normal light the ink appears white.
- Under ultraviolet light with a frequency of 254 nanometres, it emits a red colour (611 nanometres).
- After turning off the ultraviolet light, it emits a green colour (532 nanometres).
- The red colour is created by the fluorescence and the green colour is due to the phosphorescence effect.