Luminescence, the emission of photons by a substance exposed to light, has been studied in semiconductor materials for many years. The behavior of electrons as they absorb and re-emit light can provide valuable information about the properties of semiconductors, making them useful probes for characterizing electronic processes, such as those in solar cells. In 1969, it was discovered that metals also luminesce to some extent, but the exact mechanism behind this phenomenon remained unclear for decades.
Recent advancements in nanoscale temperature mapping and photochemistry applications have fueled a renewed interest in metal luminescence. Researchers at the Laboratory of Nanoscience for Energy Technologies (LNET) conducted a study focusing on gold films to better understand this process. By developing high-quality gold films and analyzing the faint glow emitted when exposed to laser beams, they were able to collaborate with theoreticians to create a fully quantitative model of photoluminescence in gold.
Using a thin film of monocrystalline gold produced with a novel synthesis technique, the researchers observed quantum mechanical effects in films up to about 40 nanometers. This was unexpected, as such effects are typically only seen in metals below 10 nm. These observations provided key spatial information about where the photoluminescence process occurs in gold, making it a valuable probe for nanoscale investigations. Additionally, the gold’s photoluminescent signal could be used to measure the material’s surface temperature, providing a new approach for studying chemical reactions at the nanoscale.
The researchers believe that their findings will significantly benefit studies in energy research, particularly in the development of solar fuels. Metals like gold and copper can play a crucial role in triggering key reactions, such as the reduction of carbon dioxide (CO2) into carbon-based products like solar fuels. Understanding these reactions at a detailed level is essential for optimizing them and combating climate change. Luminescence offers a unique way to gain insights into the surface reactions of metals, providing a new avenue for research in this field.
Overall, the study conducted by the LNET team sheds light on the photoluminescence process in gold and offers a comprehensive model that can be applied to other metals. Their research opens up new possibilities for using luminescence as a tool for understanding chemical reactions on metal surfaces, with potential implications for various applications in energy research and beyond. By harnessing the unique properties of metal luminescence, scientists may be able to unlock a deeper understanding of fundamental processes and pave the way for innovative technological advancements.