Hyperbolic metamaterials by directed self-assembly of block copolymers

Hyperbolic materials are high uniaxial anisotropic materials that display hyperbolic dispersion with distinctive properties, including negative refraction index, control over light propagation and enhanced Purcell factor. Naturally-occurring hyperbolic materials exhibit these properties only in reduced wavelength ranges, thus limiting their implementation into integrated optical devices. In order to tune the hyperbolic dispersion over broader bandwidths, artificial structures capable to guarantee a greater flexibility, i.e. hyperbolic metamaterials (HMMs), are required. So far, the realization of HMMs that work in the visible and near-infrared wavelength regions has been limited to the out-of-plane configuration due to technological costraints in the fabrication of periodic structures at sub-wavelength dimensions. Here we propose a novel concept of HMMs working in the in-plane configuration, based on the use of block copolymers (BCPs) capable to self-assemble into highly ordered polimeric masks with nanometric feature sizes and periodicity, serving as templates for the subsequent fabrication of hybrid metal-dielectric HMMs. This new class of HMMs can be exploited for metrological applications such as the enhancement of single photon source's (SPS) emission properties

Hyperbolic Metamaterials via Hierarchical Block Copolymer Nanostructures

Hyperbolic metamaterials (HMMs) offer unconventional properties in the field of optics, enabling opportunities for confinement and propagation of light at the nanoscale. In‐plane orientation of the optical axis, in the direction coinciding with the anisotropy of the HMMs, is desirable for a variety of novel applications in nanophotonics and imaging. Here, a method for creating localized HMMs with in‐plane optical axis, based on block copolymer (BCP) blend instability, is introduced. The dewetting of BCP thin film over topographically defined substrates generates droplets composed of highly ordered lamellar nanostructures in hierarchical configuration. The hierarchical nanostructures represent a valuable platform for the subsequent pattern transfer into a Au/air HMM, exhibiting hyperbolic behavior in a broad wavelength range in the visible spectrum. A computed Purcell factor as high as 32 at 580 nm supports the strong reduction in the fluorescence lifetime of defects in nanodiamonds placed on top of the HMM

Total Reflection X-ray Fluorescence Reference Materials for Cascade Impactor Air Quality Monitoring Systems

The 12th International Conference on “Instrumental Methods of Analysis” www.ima2021.gr (accessed on 8 November 2021)), was organized by the Aristotle University of Thessaloniki and National Technical University of Athens, during 20–23 September 2021 as a virtual event, providing the opportunity for high-level analytical scientists from all around the world to promote their relevant research. IMA is a biannual series of conferences that started in 1999 and cover all areas of Chemical Analysis, including the development of new techniques, modern trends, and applications in a wide range of scientific disciplines. To date, several leading analytical chemists from Greece and abroad have presented their research work at previous IMA meetings. The 12th IMA conference (in a virtual format for the first time), had the ambition to bring together some of the most talented and innovative analytical chemists from all over the world for an excellent scientific online conference. The program of the 4-day event attended by 260 participants from 23 countries, included 14 invited speakers, 73 oral presentations, and 98 poster contributions. Covered topics included: spectrometric and electrometric analysis; chromatographic, mass spectrometric, microscopic, and thermal analysis methods; proteomics, metabolomics, metallomics, and elemental speciation analysis; chemical and biosensors; field analysis—mobile analytical instruments; miniaturized analytical systems (lab-on-a-chip), micro-, and nanofluidics; immunoassays and electrophoretic separation techniques; sampling techniques and strategies; robotics and automation; quality control—quality assurance in analysis; metrology; data processing and chemometrics; environmental analysis; biomedical (ecotoxicological and clinical) and pharmaceutical analysis; food analysis; materials analysis (nanomaterials, smart/advanced materials, and surface analysis); archaeometry; and analytical chemistry markets and possibilities for commercialization. Special sessions, focused on aerosol metrology (supported by EU Project AEROMET II), advanced X-ray techniques (supported by the European X-ray Spectrometry Association), and application of chemical analysis in the study of virus spread analytics (airborne and wastewaters), were also organized within the frame of IMA-2021

influence of block copolymer feature size on reactive ion etching pattern transfer into silicon

A successful realisation of sub-20 nm features on silicon (Si) is becoming the focus of many technological studies, strongly influencing the future performance of modern integrated circuits. Although reactive ion etching (RIE), at both micrometric and nanometric scale has already been the target of many studies, a better understanding of the different mechanisms involved at sub-20 nm size etching is still required. In this work, we investigated the influence of the feature size on the etch rate of Si, performed by a cryogenic RIE process through cylinder-forming polystyrene-block-polymethylmethacrylate (PS-b-PMMA) diblock copolymer (DBC) masks with diameter ranging between 19–13 nm. A sensible decrease of the etch depth and etch rate was observed in the mask with the smallest feature size. For all the DBCs under investigation, we determined the process window useful for the correct transfer of the nanometric cylindrical pattern into a Si substrate. A structural and physicochemical investigation of the resulting nanostructured Si is reported in order to delineate the influence of various RIE pattern effects. Feature-size-dependent etch, or RIE-lag, is proved to significantly affect the obtained results

CT-based dentulous mandibular alveolar ridge measurements as predictors of crown-to-implant ratio for short and extra short dental implants

The purpose was to predict the crown-to-implant ratio variation in the edentulous posterior mandibles rehabilitated with short dental implants. Hence, vertical and horizontal dimensions of dentulous posterior mandibles in a sample of 18- to 25-year-olds were measured, and correlations of these dimensions with sex and site were investigated. Mandibular computed tomography scans from 100 subjects were considered. Vertical and horizontal bone and tooth measurements were taken at the sites of the second premolar (PM), and the mesial and distal roots of the first and second molars (M1m, M1d, M2m and M2d, respectively). A hypothetical crown-to-implant ratio (C/I R) was calculated assuming the insertion of short and extra short implants (5, 6 or 7\ua0mm), at 1.5\ua0mm from the inferior alveolar canal, maintaining the position of the existing occlusal plane. All vertical bone dimensions decreased from the PM to the M2d. Width measurements increased from the mesial (PM) to the distal sites (M1m, M1d, M2m and M2d). Males had significantly greater vertical and horizontal measurements than females at all sites. The mean C/I R was higher than 2 for all sizes of implant. The C/I R was lower for the second molar than for the second premolar, while it was similar for the first molar and the second premolar. Males had a higher C/I R than females. Computed tomography can be used to study the anatomical features of alveolar bone, and to predict some clinical aspects of prosthetic rehabilitation with implants, such as the crown-to-implant ratio in conditions of serious bone atrophy

Recent Advances in Sequential Infiltration Synthesis (SIS) of Block Copolymers (BCPs)

In the continuous downscaling of device features, the microelectronics industry is facing the intrinsic limits of conventional lithographic techniques. The development of new synthetic approaches for large-scale nanopatterned materials with enhanced performances is therefore required in the pursuit of the fabrication of next-generation devices. Self-assembled materials as block copolymers (BCPs) provide great control on the definition of nanopatterns, promising to be ideal candidates as templates for the selective incorporation of a variety of inorganic materials when combined with sequential infiltration synthesis (SIS). In this review, we report the latest advances in nanostructured inorganic materials synthesized by infiltration of self-assembled BCPs. We report a comprehensive description of the chemical and physical characterization techniques used for in situ studies of the process mechanism and ex situ measurements of the resulting properties of infiltrated polymers. Finally, emerging optical and electrical properties of such materials are discussed