Berkeley Lab Scientists Shed Light on Mystery of Raman Signal Enhancement
Surface-enhanced Raman spectroscopy, or SERS, is a surface-sensitive technique capitalizing on the enhancement of a Raman signal from a molecule placed on a rough metal surface. This surface behaves like an array of antennas, amplifying a signal billions of times or more and making it easier to detect. In recent years, this technique has been used to identify faded pigments in watercolor artist Winslow Homer’s colorless skies, and proposed as a nanoscale sensor in biological warfare. However, the chemical aspect of this enhancement has baffled researchers for decades. Foundry scientists have shed light on the mystery.
By homing in on the distribution patterns of electrons around an atom, a team of scientists team with Berkeley Lab's Molecular Foundry showed how certain vibrations from benzene thiol cause electrical charge to 'slosh' onto a gold surface (left), while others do not (right). The vibrations that cause this 'sloshing' behavior yield a stronger SERS signal.
A New Tool for Labeling Biomolecules or Cells
Foundry scientist Yi Liu and colleagues at the Albert Einstein College of Medicine at Yeshiva University have discovered a new formulation of a copper-free catalyst for imaging cell surface sugars in zebrafish. This finding serves as a highly potent and adaptive tool for labeling biomolecules or cells. The paper will appear soon in Angew. Chem. Int. Ed.
Next-Generation Chemical Mapping at the Nanoscale
(From left) Schematic of coaxial probe for imaging a carbon nanotube (left) and chemical map of carbon nanotube with chemical and (right) topographical information at each pixel. (Image from Weber, et. al)
Foundry scientists have pioneered a new chemical mapping method that provides unprecedented insight into materials at the nanoscale. Moving beyond traditional static imaging techniques, which provide a snapshot in time, these new maps will guide researchers in deciphering molecular chemistry and interactions at the nanoscale—critical for artificial photosynthesis, biofuels production and light-harvesting applications such as solar cells
A Breakthrough in Nanocomposites for High-Capacity Hydrogen Storage
Foundry scientists have designed a new composite material for hydrogen storage consisting of nanoparticles of magnesium metal sprinkled through a matrix of polymethyl methacrylate, a polymer related to Plexiglas. This pliable nanocomposite rapidly absorbs and releases hydrogen at modest temperatures without oxidizing the metal after cycling—a major breakthrough in materials design for hydrogen storage, batteries and fuel cells.
Bringing Plasmonic Nanofields into Focus
Foundry scientists have engineered an innovative imaging technique to visualize plasmonic fields with nanoscale resolution. This technique, which harnesses light within a bowtie-shaped structure, could be used to measure the performance of plasmonic devices.
In previous work, Jim Schuck and colleagues engineered bowtie-shaped plasmonic devices designed to capture, filter and steer light at the nanoscale. These nano-color sorter devices served as antennae to focus and sort light in tiny spaces to a desired set of colors or energies—crucial for filters and other detectors. In this latest advance, Schuck and his Berkeley Lab team used their innovative imaging concept to visualize plasmonic fields from these devices with nanoscale resolution.