177 research outputs found
Plasmonics: The future is ultrafast and ultrasmall
Get PDFPlasmonics has been a flourishing field since the late ‘80s of the last century. Given the number of outstanding developments even without resorting to metrics–it is straightforward to address the 2 decades crossing the new millennium as the golden era of Plasmonics. The unique capabilities of plasmonic nanostructures to collect, direct and enhance light at length scales much below the operating wavelength granted them the name “antennas for light”. These features were crucial for the vast deployment of Plasmonics to a variety of tasks, spanning from light harvesting (Atwater and Albert 2010) to molecular sensing (Homola 2008; Saha et al., 2012), bio-imaging (Meola et al., 2018; Bocková et al., 2019; Wu et al., 2019) and plasmon-enhanced spectroscopy (Zhang et al., 2013, Ding et al., 2016). Another recently growing field is that of plasmon-enhanced catalysis, which could be of crucial importance for hydrogen synthesis (Ezendam et al., 2022) with significant consequences for sustainability. Despite its indisputable key role in basic and applied research, the disruptive fallout of Plasmonics in life and society is still mainly restricted to medical diagnostic tools, as demonstrated by the antigenic lateral flow test employed to detect SARS-CoV-2, which is massively employed during this last pandemic. The first clinical pilot study of a device for prostate cancer treatment, carried out by Prof. Halas using photothermal ablation via gold nanoshells (Rastinehad et al., 2019), represents another major landmark in nanomedicine
Assembly and manipulation of nanophotonic elements in a fluid: towards reconfigurable photonic structures on a chip
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Information storage and retrieval in a single levitating colloidal particle
No full textThe binary switch is a basic component of digital information. From phase-change alloys to nanomechanical beams, molecules and atoms, new strategies for controlled bistability hold great interest for emerging technologies. We present a generic methodology for precise and parallel spatiotemporal control of nanometre-scale matter in a fluid, and demonstrate the ability to attain digital functionalities such as switching, gating and data storage in a single colloid, with further implications for signal amplification and logic operations. This fluid-phase bit can be arrayed at high densities, manipulated by either electrical or optical fields, supports low-energy, high-speed operation and marks a first step toward ‘colloidal information’. The principle generalizes to any system where spatial perturbation of a particle elicits a differential response amenable to readout
Imaging single molecules by optical absorption at room temperature
No full textSince its first development and applications in the early 1990s, single molecule detection has become a powerful tool for a wide range of studies, ranging from biophysics to quantum optics. However, this approach has been limited so far to species with high fluorescence quantum yield. Over the past few years, we have developed extinction detection and spectroscopy as an alternative to fluorescence for investigating single nano-objects such as metallic nanoparticles, viruses, dye molecules, and quantum dots [1-5]. The contrast mechanism at work relies on the coherent interference between the incident beam and the light scattered by the nano-object. © 2011 IEEE
Single-Molecule Sensitivity in Optical Absorption at Room Temperature
No full textSensitive detection of condensed matter is of utmost importance in fundamental research as well as cutting-edge applications such as molecular analytics and diagnostics. Until very recently, all existing methods for the detection of single molecules at room temperature have required highly efficient fluorophores. Here, we demonstrate, for the first time, that single molecules can also be detected via standard modulation-free absorption measurements. Our work extends single-molecule detection to a huge class of materials that absorb light but do not fluoresce efficiently. © 2010 American Chemical Society
Single-molecule imaging by optical absorption
No full textTo date, optical studies of single molecules at room temperature have relied on the use of materials with high fluorescence quantum yield combined with efficient spectral rejection of background light. To extend single-molecule studies to a much larger pallet of substances that absorb but do not fluoresce, scientists have explored the photothermal effect1, interferometry2,3, direct attenuation4 and stimulated emission5. Indeed, very recently, three groups have succeeded in achieving single-molecule sensitivity in absorption6-8. Here, we apply modulation-free transmission measurements known from absorption spectrometers to image single molecules under ambient conditions both in the emissive and strongly quenched states. We arrive at quantitative values for the absorption cross-section of single molecules at different wavelengths and thereby set the ground for single-molecule absorption spectroscopy. Our work has important implications for research ranging from absorption and infrared spectroscopy to sensing of unlabelled proteins at the single-molecule level. © 2011 Macmillan Publishers Limited. All rights reserved
Chiral surface waves for enhanced circular dichroism
Get PDFWe present a novel chiral sensing platform that combines a one-dimensional photonic crystal design with a birefringent surface defect. The platform sustains simultaneous transverse electric and transverse magnetic surface modes, which are exploited to generate chiral surface waves. The present design provides homogeneous and superchiral fields of both handednesses over arbitrarily large areas in a wide spectral range, resulting in the enhancement of the circular dichroism signal by more than two orders of magnitude, thus paving the road toward the successful combination of surface-enhanced spectroscopies and electromagnetic superchirality
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