(Nanowerk News) Teams led by professors Jinyang Liang and Fiorenzo Vetrone from the Énergie Matériaux Télécommunications Research Centre at the Institut national de la recherche scientifique (INRS) have developed a new system for imaging nanoparticles. It consists of a high-precision, short-wave infrared imaging technique capable of capturing the photoluminescence lifetimes of rare-earth doped nanoparticles in the micro- to millisecond range. This discovery, which was published in the journal Advanced Science (“Short-wave Infrared Photoluminescence Lifetime Mapping of Rare-Earth Doped Nanoparticles Using All-Optical Streak Imaging”), paves the way for promising applications, particularly in the biomedical and information security fields. Rare-earth elements are strategic metals that possess unique light-emitting properties that make them very attractive research tools in cutting-edge science. What’s more, the photoluminescence lifetime of nanoparticles doped with these ions has the advantage of being minimally affected by external conditions. As a result, measuring it through imaging provides data from which accurate and highly reliable information can be derived. Although this field is seeing remarkable progress, existing optical systems for this type of measurement were less than ideal. “Until now, existing optical systems have offered limited possibilities due to inefficient photon detection, limited imaging speed, and low sensitivity,” explains Professor Jinyang Liang, a specialist in ultrafast imaging and biophotonics. To date, the most common technique for measuring the photoluminescence lifetime of rare-earth doped nanoparticles has involved counting time-correlated single photons. “This method requires a large number of repeated excitations at the same location because the detector can only process a limited number of photons for each excitation,” says the study’s first author Miao Liu, a Ph.D. student in energy and materials science supervised by Profs. Liang and Vetrone. However, the long photoluminescence lifetimes of rare-earth doped nanoparticles in the infrared spectrum, from hundreds of microseconds to several milliseconds, restrict the excitation’s repetition rate. As a result, the pixel dwelling time needed to build the photoluminescence intensity decay curve is much longer.
