Organized Particles (IMAGE) Penn State Caption A new method uses ultraviolet light and small amounts of gold or titanium dioxide nanoparticles to gather larger particles at the point of light. This method was used to gather polystyrene particles, which form a well-packed structure called a colloid crystal, as depicted in this image. Credit Sen Lab, Penn State Usage Restrictions Credit must be provided. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.