Sum-frequency generation (SFG) is a powerful vibrational spectroscopy that can selectively probe molecular structures at surfaces and interfaces, but its spatial resolution has been limited to the micrometer scale by the diffraction limit of light. Here, we overcame this limitation by utilizing a highly confined near field within a plasmonic nanogap and successfully extended the SFG spectroscopy into nanoscopic regime with ~10-nm spatial resolution. We also established a comprehensive theoretical framework that accurately describes the microscopic mechanisms of this near-field SFG process. These experimental and theoretical achievements collectively represent a groundbreaking advancement in near-field second-order nonlinear nanospectroscopy, enabling direct access to correlated chemical and topographic information of interfacial molecular systems at the nanoscale.

Tokyo, Japan – Researchers from Tokyo Metropolitan University have studied how polymer-coated fertilizer (PCF) applied to fields ends up on beaches and in the sea. They studied PCF deposits on beaches around Japan, finding that only 0.2% of used PCFs are washed into rivers and returned to the coastline. When there are canals connecting fields to the sea, this rises to 28%. Their findings highlight a potentially significant “sink” in the global circulation of plastics.

Every year, billions of cigarette butts are discarded worldwide, creating one of the most pervasive and persistent forms of environmental litter. Now, researchers have demonstrated that this problematic waste can be converted into advanced carbon materials capable of powering next generation energy storage devices.