Beneath the glitter

Published: Sunday 30 November 1997

The colour of a substance is produced when electrons in a material absorb certain wavelengths of light and jump to a higher energy state. One can change optical properties of a substance by restricting electrons from jumping up. This has up technique has uptill now worked only in gases. But now, scientists have demonstrated that this technique can work in solids also. Researchers at the Wayne State University in Detroit, USA, claim to have used a magnetic field and microwaves to improve transparency of rubies. They cooled the ruby to about 270C and then placed it in a magnetic field. By using microwaves of right wavelength, they were able to restrict electrons of the ruby atoms from absorbing the light and jumping to a higher state. Experts say that this method may help design better optical switches ( Physical Review Letters , 28 July 1997).

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