ORCID Profile
0000-0002-3052-9947
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Publisher: American Chemical Society (ACS)
Date: 06-08-2020
Publisher: Royal Society of Chemistry (RSC)
Date: 2008
DOI: 10.1039/B803738H
Abstract: Isotopically substituted rhodamine dyes provide ideal probes for the study of single-molecule surface enhanced Raman scattering (SM-SERS) events through multiple-analyte techniques. Isotopic editing should, in principle, provide probes that have identical chemical properties (and surface chemistries) while exhibiting at the same time distinct Raman features which enable us to identify single-molecule SERS events. We present here a specific ex le of two-analyte SM-SERS based on the isotopic substitution of a methyl ester rhodamine dye. The dyes are carefully characterized (in both standard and SERS conditions) to confirm experimentally their similar chemical properties. We then demonstrate their utility for bi-analyte SERS (BiASERS) experiments and, as an ex le, highlight the transition from a single, to a few, to many molecules in the statistics of SM-SERS signals.
Publisher: Wiley
Date: 25-04-2023
DOI: 10.1002/LNO.12345
Abstract: Coralline algae are an essential element of benthic ecosystems throughout the ocean's photic zone. Yet, the role of light in shaping the physiology of coralline algae from cold‐water, low‐light habitats is poorly understood. Here, we assess the calcification physiology of five cool temperate coralline algae in response to different irradiance levels over 3 months. We show that in contrast to current models focused on warmer water species, previously observed enhancement of calcification rates by photosynthesis is largely limited to lower irradiances, and that the removal of CO 2 from the calcifying fluid is not the underlying mechanism of this enhancement. Instead, this most likely occurs via two processes: (1) increased ion pumping rates to elevate the calcium carbonate saturation state in the calcifying fluid and (2) a higher daytime pH in the diffusion boundary layer that raises calcifying fluid pH. However, as irradiance increases, ion pumping becomes increasingly saturated limiting further enhancements. Our results also suggest the existence of two calcification strategies in coralline algae and indicate that magnesium incorporation is determined by the magnesium to calcium ratio in the calcifying fluid ([Mg] CF /[Ca] CF ). This study adds to our mechanistic understanding of calcification in coralline algae and fills in much needed knowledge about the role of light in controlling their physiology.
Publisher: Optica Publishing Group
Date: 14-06-2021
DOI: 10.1364/AO.428450
Abstract: We present a rigorous approach for measuring the throughput of an integrating sphere, from which the so-called sphere multiplier M can be derived. The critical ingredients of this approach are: (i) the transmitted power is measured at the base of an integrating port to avoid non-ideal port effects associated with reflections on the port wall (ii) to implement this last point, optical fibers are used for light collection, providing a well-defined collection area and numerical aperture (iii) the angular-dependent fiber throughput and detector sensitivity are determined experimentally and accounted for. We demonstrate in particular that a more realistic theory, accounting for the propagation of skew rays through the fiber, is needed to quantitatively model the fiber effect on the measured sphere throughput. We show experimentally that failure to fulfill these three points produces erroneous results, by as much as 50%. With an accurate experimentally derived sphere multiplier, agreement with theory is then obtained only if realistic ports (with non-zero reflectivity) are assumed. This provides experimental evidence for recent theoretical predictions of the importance of realistic ports [Tang et al. , Appl. Opt. 57 , 1581 ( 2018 ) APOPAI 0003-6935 10.1364/AO.57.001581 ]. Using the same experimental techniques, we also present clear experimental proof of two other predictions from that study: that the angular distribution exiting the port is strongly altered and that the overall port transmittivity is drastically reduced for high aspect ratio ports. This work will provide a solid basis for future quantitative measurements of absolute throughput and for further developments of the theory of integrating spheres.
Publisher: Elsevier BV
Date: 10-2004
Publisher: American Chemical Society (ACS)
Date: 03-09-2019
Publisher: AIP Publishing
Date: 02-03-2004
DOI: 10.1063/1.1645637
Abstract: Atomic force microscopy and photoluminescence spectroscopy (PL) have been used to study asymmetric bilayer InAs quantum dot (QD) structures grown by molecular-beam epitaxy on GaAs(001) substrates. The two QD layers were separated by a GaAs spacer layer (SL) of varying thickness and were grown at different substrate temperatures. Grown independently, these two layers would exhibit a widely different QD number density, and this technique therefore enables us to assess the influence of the strain fields created by the dots in the first layer on the second-layer QD nucleation and characteristics. For very large SLs (& nm), total strain relief causes the QD nucleation to be controlled exclusively by the substrate temperature, which influences the migration of In adatoms. In this case, the optical and morphological properties of the second QD layer are identical to a structure with a single QD layer grown at the same temperature. In structures with a much smaller SL, strain effects dominate over the effect of temperature in controlling the nucleation of the QDs, thereby fixing the second-layer QD number density to that of the first (templating effect). There is also evidence that strain relaxation is present in the QDs of the second layer and that this is crucial for extending their emission wavelength. The optimum SL thickness is shown to be 11 nm, for which low-temperature PL emission peaks at 1.26 μm, with a full width at half-maximum of only 15 meV. Intermediate SL thicknesses exhibit broad QD size distributions, with strain effects only partly influencing the QD growth in the second layer.
No related organisations have been discovered for Eric Le Ru.
Start Date: 2023
End Date: 2026
Funder: Marsden Fund
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