Identifying and imaging polymer functionality at high spatial resolution with core-loss EELS.

Electron energy loss spectroscopy (EELS) is a proven tool for probing materials chemistry at high spatial resolution. Core-loss EELS fine structure should allow measurement of local polymer chemistry. For organic materials, sensitivity to radiolysis is expected to limit the resolution achievable with EELS: but core-loss EELS has proven difficult at any resolution, yielding inconsistent spectra that compare unfavorably with theoretically analogous x-ray absorption spectra.

Manipulating acoustic and plasmonic modes in gold nanostars.

In this contribution experimental evidence of plasmonic edge modes and acoustic breathing modes in gold nanostars (AuNSs) is reported. AuNSs are synthesized by a surfactant-free, one-step wet-chemistry method. Optical extinction measurements of AuNSs confirm the presence of localized surface plasmon resonances (LSPRs), while electron energy-loss spectroscopy (EELS) using a scanning transmission electron microscope (STEM) shows the spatial distribution of LSPRs and reveals the presence of acoustic breathing modes.

Heterodimeric Plasmonic Nanogaps for Biosensing.

We report the study of heterodimeric plasmonic nanogaps created between gold nanostar (AuNS) tips and gold nanospheres. The selective binding is realized by properly functionalizing the two nanostructures; in particular, the hot electrons injected at the nanostar tips trigger a regio-specific chemical link with the functionalized nanospheres. AuNSs were synthesized in a simple, one-step, surfactant-free, high-yield wet-chemistry method.

Multimodal Evidence of Mesostructured Calcium Fatty Acid Deposits in Human Hair and Their Role on Hair Properties.

We provide the first conclusive evidence for the presence of exogenous calcium fatty acid deposits, which not only form in-between the cuticle layers in the lipid-rich cell membrane complex, but also grow to dimensions large enough to cause the structure to bulge, thereby impacting the optical and mechanical properties of the hair fiber. The composition and phase of these deposits were probed using a multimodal analytical approach with spatially resolved techniques including synchrotron micro X-ray fluorescence coupled with X-ray scattering, focused ion beam (FIB)-scanning electron microscopy (SEM), scanning transmission electron microscopy, X-ray energy dispersive spectroscopy, and Fourier transform infrared and Raman imaging where the collective analysis is consistent with a meso-phase composed of calcium C/C saturated fatty acids from natural sources such as sebum. X-ray microtomography and serial "slice and view" FIB/SEM both reveal the location and volumetric shape of the deposits.

A Small Spot, Inert Gas, Ion Milling Process as a Complementary Technique to Focused Ion Beam Specimen Preparation.

This paper reports on the substantial improvement of specimen quality by use of a low voltage (0.05 to ~1 keV), small diameter (~1 μm), argon ion beam following initial preparation using conventional broad-beam ion milling or focused ion beam. The specimens show significant reductions in the amorphous layer thickness and implanted artifacts.

Crystallization kinetics of cerium oxide nanoparticles formed by spontaneous, room-temperature hydrolysis of cerium(iv) ammonium nitrate in light and heavy water.

A stable sol of cerium oxide nanoparticles forms spontaneously when cerium(iv) ammonium nitrate (CAN) is dissolved in room-temperature water at mM concentrations. Electron microscopy experiments reveal the formation of highly crystalline cerium oxide particles several nm in diameter and suggest that they are formed from amorphous particles that are similar in size. Under the low pH conditions of the experiments, the nanoparticles form a stable dispersion and show no evidence of aggregation, even many months after synthesis.

Nature of the interfaces between the constituent phases in the high entropy alloy CoCrCuFeNiAl.

The interfaces between the phase separated regions in the dendritic grains of laser-deposited samples of the high entropy alloy CoCrCuFeNiAl have been studied using aberration-corrected analytical (scanning) transmission electron microscopy ((S)TEM). The compositional variations have been determined using energy dispersive x-ray spectroscopy (EDS) in (S)TEM. It was found that between B2, consisting mainly of Al, Ni, Co, and Fe, and disordered bcc phase, consisting mainly of Cr and Fe, there is a transition region, approximately 1.