Pink diamond's photochromic behavior solved but its color is still a mystery

Jan. 8, 2013
Crawley, Australia--Scientists at the University of Western Australia have explained the photochromic behavior of pink diamonds in an attempt to learn in detail why they possess their pink color.

(Image: Fancy Diamonds)

Crawley, Australia--Scientists at the University of Western Australia have explained the photochromic behavior of pink diamonds in an attempt to learn in detail why they possess their pink color. Natural pink diamonds have defect centers that allow optically controllable and reversible photochromism at room temperature.

“We have pumped these diamonds with various wavelengths of light and measured the response in both time and absorption intensity,” says lead author and PhD student Keal Byrne. “What we’ve seen is that the diamond color -- the amount of absorption that gives it the pink color -- is dependent on both the wavelength and intensity of the light, and what that is consistent with is a model of electron transfer between the unknown pink defect and other defects in the lattice.”

The elusive color center
The pump light causes competing types of photoionization at different defect centers, producing photochromism; the researchers were able to experimentally determine the ionization cross-sections of the relevant defect centers. However, the researchers also found that the defect centers responsible for many other diamond colors (blue, yellow, and others) do not explain how pink diamonds get their color. “Coloration in diamonds is due to crystalline defects in the crystal lattice, which are also known as color centers as they induce color,” says Byrne. “The color center responsible for pink coloration is unknown.”

The team modeled the pink-diamond photochromic process as "an optically-driven electronic transition between two (or more) separate defect trap states, one of which acts as a ground state for the 390 nm and 550 nm absorption bands."1 The depth of the two bands can be reduced under UV illumination, bleaching the diamond; the color can be restored with longer-wavelength light.

“So we’re trying to work out what these new energy levels are that are unique to the pink diamond and by that way we can work out what properties it has and what use it might have,” notes Byrne.

REFERENCE:

K. S. Byrne et al., Diamond and Related Materials, Vol. 30, p. 31, November 2012.

Source: http://www.sciencewa.net.au/topics/industry-a-resources/item/1820-pink-diamond-%E2%80%98behaviour%E2%80%99-solved-but-colour-still-a-mystery.html



Sponsored Recommendations

Demonstrating Flexible, Powerful 5-axis Laser Micromachining

Sept. 18, 2024
Five-axis scan heads offer fast and flexible solutions for generating precise holes, contoured slots and other geometries with fully defined cross sections. With a suitable system...

Enhance Your Experiments with Chroma's Spectra Viewer

Sept. 5, 2024
Visualize and compare fluorescence spectra with our interactive Spectra Viewer tool. Easily compare and optimize filters and fluorochromes for your experiments with this intuitive...

Optical Filter Orientation Guide

Sept. 5, 2024
Ensure optimal performance of your optical filters with our Orientation Guide. Learn the correct placement and handling techniques to maximize light transmission and filter efficiency...

Ensure Optimal Performance with Shortpass Filters

Sept. 5, 2024
Achieve precise wavelength blocking with our Shortpass Filters. Ideal for applications requiring effective light transmission and cutoff, these filters ensure optimal performance...

Voice your opinion!

To join the conversation, and become an exclusive member of Laser Focus World, create an account today!