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This study reports the production of mid-infrared (MIR) porous anodic alumina (PAA)-based microcavities with tunable optical quality. The spectral position of the cavity resonance peak (λC), along with its intensity (IR) and Q-factor, varies depending on the geometric positioning of the cavity layer within the multilayer stack of alternating low- and high-porosity layers, as well as the type of cavity produced—either by high voltage (CvH-type) or low voltage (CvL-type) pulses. In most cases, PAA microcavities with CvH-type cavity layers exhibited superior light confinement properties compared to those with CvL-type cavities. Additionally, shifting the cavity layer from the center toward the edges of the multilayer stack enhanced the intensity of the resonance peak. For PAA microcavities with CvH-type cavity layers, the highest intensity (IR = 53%) and the largest Q-factor (Q = 31) were recorded at λC of around 5.1 µm. The anodization approach used in this study demonstrates significant potential for designing PAA-based microcavities with high optical performance in the MIR spectral region, especially with further refinement of electrochemical parameters. These findings pave the way for the development of new photonic materials specifically tailored for the MIR spectral range, broadening their applications in various optoelectronic and sensing technologies. [ABSTRACT FROM AUTHOR]

Heterostructured transition metal dichalcogenides (TMDs) have received much attention due to their tunable optical and electronic properties. Here, a strategy for facile fabrication of porous anodic alumina (PAA) membrane‐supported monolayer molybdenum disulfide (MoS2) is described. PAA is either empty or filled with gold nanoparticles (AuNPs). Such nanopore/nanosphere‐supported MoS2 (i.e., PAA‐MoS2 and PAA‐Au‐MoS2) exhibits greatly enhanced optical performances compared with those of silicon wafer‐supported MoS2 (i.e., Si/SiO2‐MoS2). Notably, 11‐fold Raman enhancement, 13‐fold photoluminescence enhancement, and 419‐fold second‐harmonic generation enhancement are achieved in PAA‐Au‐MoS2. Moreover, the optical enhancement mechanism of this unique structure is proposed. This work provides a platform for the construction of curved/heterostructured TMDs and exploration of their strong light‐matter interactions. [ABSTRACT FROM AUTHOR]

Heterostructured transition metal dichalcogenides (TMDs) have received much attention due to their tunable optical and electronic properties. Here, a strategy for facile fabrication of porous anodic alumina (PAA) membrane‐supported monolayer molybdenum disulfide (MoS2) is described. PAA is either empty or filled with gold nanoparticles (AuNPs). Such nanopore/nanosphere‐supported MoS2 (i.e., PAA‐MoS2 and PAA‐Au‐MoS2) exhibits greatly enhanced optical performances compared with those of silicon wafer‐supported MoS2 (i.e., Si/SiO2‐MoS2). Notably, 11‐fold Raman enhancement, 13‐fold photoluminescence enhancement, and 419‐fold second‐harmonic generation enhancement are achieved in PAA‐Au‐MoS2. Moreover, the optical enhancement mechanism of this unique structure is proposed. This work provides a platform for the construction of curved/heterostructured TMDs and exploration of their strong light‐matter interactions. [ABSTRACT FROM AUTHOR]

Etidronic acid, used in aluminum anodization, has a great potential for the fabrication of porous anodic alumina (PAA) with large cell sizes (>540 nm). PAAs are particularly suited to applications in optics and photonics where large-scale periodicity corresponding to visible or infrared light is needed. Additionally, such PAAs should be characterized by long-range pore ordering. However, to obtain regular pore arrangement in an etidronic electrolyte, the anodization should be performed at high electric fields using relatively high temperatures, which makes the process challenging in terms of its stability. To stabilize the process, the electrolyte can be modified with ethanol. In this work, the impact of ethanol on pore geometry and a level of pore ordering is systematically analyzed. It is shown that the additive tends to reduce pore ordering. Moreover, by changing the anodizing temperature and the amount of ethanol, it is possible to tune the porosity of the PAA template. At 20 °C, porosity drops from 14% in PAA grown in a pure water-based electrolyte to ca. 8% in PAA fabricated in the 1:3 v/v EtOH:H2O electrolyte. The larger PAA thickness obtained for the same charge density strongly suggests that PAA formation efficiency increases in the 1:3 v/v EtOH:H2O mixture. [ABSTRACT FROM AUTHOR]

Humidity sensing at low RH%, its mechanism, and even lowering further minimum detection limit has no clear answer as of now. Porous anodic alumina (PAA), though an excellent hygroscopic material; still lacks a comprehensive theory on how to lower the minimum detection limit (LOD) to the sub-RH level. In this report, in addition to the pore morphology design, the effect of electrolyte driven anion concentration on PAA surface has been suitably fine-tuned by increasing the attachment of hydroxyl bond density. The organic solvent like glycerol mixed with the anodizing electrolyte has been chosen in proper concentration; leading to enhance the degree of ionic attachment to the PAA surface, hence increase in the sensitivity and the lower detection limit. A lower detection limit of 0.5 RH% is obtained with optimized glycerol concentration, examined through FTIR spectroscopy, which is a direct consequence of increased surface anion concentration that facilitates the adsorption of water vapor molecules on the surface. The developed sensor shows wide detection range 0.5-99 RH%, ultrahigh sensitivity of 275.4 pF/RH%, very fast response- and recovery time of 3 s and 15 s and negligible drift over cycling over 30 times for 0-11.4 RH%. The sensor provides a low-cost alternative solution specifically, to industries having low moisture monitoring requirements e.g., tea and lithium battery manufacturing industry. [ABSTRACT FROM AUTHOR]

A robust and reliable method for fabricating porous anodic alumina (PAA)-based distributed Bragg reflectors (DBRs), operating in mid-infrared (MIR) spectral region, is presented. The method relies on application of high (UH) and low (UL) voltage pulse sequence repeated in cycles. PAA-based DBR consists of alternating high-(dH) and low-porosity (dL) layers translated directly into periodically varied refractive index. Two anodization modes were used: time- and charge density-controlled mode. The former generated dH + dL pairs with non-uniform thickness (∆d) and effective refractive index (∆neff). It is supposed, that owing to a compensation effect between the ∆d and ∆neff, the photonic stopbands (PSBs) were symmetrical and intensive (transmittance close to zero). Under the charge density-controlled mode dH + dL pairs of uniform thickness were formed. However, the remaining ∆neff provided an asymmetrical broadening of PSBs. Furthermore, it is demonstrated that the spectral position of the PSBs can be precisely tuned in the 3500–5500 nm range by changing duration of voltage pulses, the amount of charge passing under subsequent UH and UL pulses, and by pore broadening after the electrochemical synthesis. The material can be considered to be used as one-dimensional transparent photonic crystal heat mirrors for solar thermal applications.

Over the past few years, researchers have made numerous breakthroughs in the field of aluminum anodizing and faced the problem of the lack of adequate theoretical models for the interpretation of some new experimental findings. For instance, spontaneously formed anodic alumina nanofibers and petal-like patterns, flower-like structures observed under AC anodizing conditions, and hierarchical pores whose diameters range from several nanometers to sub-millimeters could be explained neither by the classical field-assisted dissolution theory nor by the plastic flow model. In addition, difficulties arose in explaining the basic indicators of porous film growth, such as the nonlinear current–voltage characteristics of electrochemical cells or the evolution of hexagonal pore patterns at the early stages of anodizing experiments. Such a conceptual crisis resulted in new multidisciplinary investigations and the development of novel theoretical models, whose evolution is discussed at length in this review work. The particular focus of this paper is on the recently developed electroconvection-based theories that allowed making truly remarkable advances in understanding the porous anodic alumina formation process in the last 15 years. Some explanation of the synergy between electrode reactions and transport processes leading to self-organization is provided. Finally, future prospects for the synthesis of novel anodic architectures are discussed.

In this work, nanocrystalline silicon (nc-Si) are deposited in a porous anodic alumina (PAA) matrix by a radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) method. The rapid thermal annealing (RTA) effect on morphological and microstructural properties of nc-Si/PAA structure is investigated by SEM, EDX, XRD technique and Raman spectroscopy. Crystallization of the amorphous silicon is obtained after annealing at was 550 °C during a time ranging from 10 to 120 min. The effect of thermal annealing on the optical properties of nc-Si/PAA structure was studied by Spectroscopic Ellipsometry (SE) in the spectral range 0.3–0.8 μm. The Ellipsometric analysis demonstrated the formation of two separate layers during the annealing process. A silicon/alumina alloy as the upper layer and a polysilicon film at the bottom and in contact with the alumina barrier layer. The optical constants, thickness and the composition of each film have been estimated from the SE data using Bruggeman effective medium approximation (BEMA). PL spectroscopy was used to investigate the bandgap energy of nc-Si embedded within the PAA matrix, the origin of emission PL spectra as well as the observed red-shift have been discussed. [ABSTRACT FROM AUTHOR]

In this report, we are going to present the development and optimization of high-performance porous alumina growth having a large surface to volume ratio for ultra-high sensitive humidity sensing. The control of the structure of pores, such as the diameter of pores, depth of porous layer, etc., has shown crucial implications for the sensitivity of sensor; and there are precisely fine-tuned with the anodization process parameters. The sensitivity of the prepared sensors reaches upto 793.02% while reported sensitivity for conventional capacitive humidity sensors is much less. Besides, the prepared sensor maintains its fair responsivity as well as sensitivity even up to 100 KHz unlike 10 KHz reported by other researchers so far; and it gives an added advantage for its applications where humidity measurement at high frequencies are required The samples are characterized by Field Emission Scanning Electron Microscopy (FESEM, FEI NNS 450) to support the results and impedance spectroscopy were employed for the electrical characterization of the sensor. An equivalent electrical circuit is obtained to represent the electrical performance at different humidity level and it is in good agreement with the observed results. [ABSTRACT FROM AUTHOR]

Porous Anodic Alumina (PAA) membranes have been fabricated from pure and doped aluminum films (Pure Al, Al–0.5wt.%Cu and Al–1wt.%Si) by the one-step anodization method at room temperature. Formation of the PAA has been performed by three different electrolytes, namely: sulfuric (1 M), oxalic (0.3 M) and phosphoric (0.75 M) acids. For this purpose, potentiostatic anodization in a two-electrode cell configuration has been carried out. High quality alumina with straight pores have been obtained starting from pure aluminum metal films. It is found that, different types of branched structures are formed by aluminum films doped with impurities such as Si and Cu. The relationship between the electrochemical current response and the obtained pore architectures are discussed. Oxide formation rates, barrier layer thickness, vertical and horizontal inter-pore distances are investigated. The present synthesized templates have a large surface area make it one of the mostpopular nanomaterial with applications across a gamut of areas including, energy storage, sensors and biosensors. [ABSTRACT FROM AUTHOR]

Wettability is a critical factor for the design and fabrication of micro- and nanoscale structures. Manipulating surface wettability using physical methods such as electrowetting is advantageous for many engineering applications. This study examines the effects of an electrical potential on the wettability of a porous metallic nanostructure (PMN). Experimental results in wetting performance showed that applying an electrical potential induces an increase in wettability. Wettability was also affected by pore size, with larger pore sizes exhibiting less wetting. Based on the Young–Lippmann model, a modified equation was proposed to express the force balance between absorbing and repelling at the pore walls. The force balance model was established in terms of the height of a water droplet in the pore. This research reveals that PMNs can be used for numerous electrowetting applications and for fabricating other types of nanostructures. [ABSTRACT FROM AUTHOR]

Porous anodic alumina (PAA) membranes with increasing pore diameters ( D p ) and various interpore distances ( D c ) were fabricated and the water contact angles (WCAs) on the PAAs' surface were determined. No correlation was observed between the WCAs and D p unless the D c was taken into account. The WCAs were dependent on porosity ( P ); according to this dependence, there is a critical value of P beyond which the WCAs drop substantially. The critical P was ~ 50% and the maximal WCA obtained for this P value was 102°. No effect of pore arrangement on the water wettability was observed — the PAAs characterized by poor hexagonal pore ordering (the PAA NO) did not show any deviations from the observed trends. After modifying the PAAs surfaces by lauric acid and perfluorooctyltrichlorosilane (FOTS), the samples became more hydrophobic. For the FOTS-modified PAAs with the highest D p (> 230 nm) and D c (> 260 nm), the surfaces became superhydrophobic. The results obtained in this work can be used for controlling the PAAs' surface topography and chemistry to attain desired surface properties, ranging from hydrophilicity to ultrahydrophobicity. [ABSTRACT FROM AUTHOR]

Highly ordered porous anodic alumina (PAA) with interpore distances ( D c ) tunable in the range of 250–400 nm have been fabricated in a two-step anodization. In the first step a modified hard anodization (HA) was developed, which allowed for extension of the maximal anodizing voltage up to 220 V, giving rise to larger pores intervals than usually attained in HA (∼300 nm). The HA process was carried out in 0.3 M ethanol-free (group I) and ethanol-modulated (group II) oxalic acid electrolytes. It was observed that ethanol worsens the hexagonal arrangement of Al concavities and strongly affects the D c performance with respect to applied voltages. The Al nano-concave arrays prepared in the modified HA were subsequently used in the second anodization, performed in 0.1 M phosphoric acid solution. The geometrical features and regularity of Al concavities were directly transferred to porous anodic alumina (PAA). An excellent long-range ordering of pores was achieved when the guidance effect of regular hexagonal Al concaves prepared in ethanol-free electrolyte was reinforced by the self-ordering conditions prevailing in 0.1 M phosphoric acid solution at voltages close to 195 V. [ABSTRACT FROM AUTHOR]

In this work, cadmium selenide nanocrystals (CdSe NCs) were embedded into porous anodic alumina (PAA) template by simple immersion in aqueous solution containing l -cysteine (Cys) functionalized CdSe NCs and water. The prepared samples were heat treated at different temperatures between 150 and 300 °C during 30 min under air. The effect of thermal treatment under air on the CdSe NCs/PAA has been shown from morphological, microstructural and optical studies. Several characterization techniques such as scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD) spectroscopy were used to investigate the surface morphology and microstructural properties of CdSe nanoparticles on the PAA template as function of air-annealing temperature. XRD study shows the transformation phase of deposited CdSe nanoparticles on the PAA template from cubic structure to hexagonal structure at 300 °C. The morphology of CdSe nanorods array which are into the PAA surface were exhibited by AFM scan. Optical properties of CdSe NCs into PAA have been studied at different air-annealing temperatures using optical absorption and photoluminescence (PL) spectroscopy. The results showed that the crystal quality was significantly improved with the annealing temperature increase, bringing about an enhancement in PL and a decrease in optical band gap from 2.44 to 2.2 eV exhibiting a red shift. [ABSTRACT FROM AUTHOR]

Abstract: Porous anodic alumina (PAA) films produced by the anodization technique have made possible the mass production of porous nano-scale structures where the pore height and diameter are controllable. A metal interlayer is observed to have a significant influence on the characteristics of these PAA nanostructures. In this study, we investigate in-depth the effect of the current density on the properties of porous anodic alumina nanostructures with a metal interlayer. A thin film layer of tungsten (W) and titanium (Ti) was sandwiched between a porous anodic alumina film and a silicon (Si) substrate to form PAA/W/Si and PAA/Ti/Si structures. The material and optical characteristics of the porous anodic alumina nanostructures, with and without a metal interlayer, on silicon substrates were studied using the scanning electron microscopy, X-ray diffraction (XRD), and temperature-dependent photoluminescence (PL) measurements. The current densities of the porous anodic alumina nanostructures with the metal interlayer are higher than for the PAA/Si, resulting in an increase of the growth rate of the oxide layer. It can be observed from the X-ray diffraction curves that there is more aluminum oxide inside the structure with the metal interlayer. Furthermore, it has been found that there is a reduction in the photoluminescence intensity of the oxygen vacancy with only one electron due to the formation of oxygen vacancies inside the aluminum oxide during the re-crystallization process. This leads to competition between the two kinds of different oxygen-deficient defect centers (F+ and F centers) in the carrier recombination mechanism from the PL spectra of the porous anodic alumina nanostructures, with and without a metal interlayer, on silicon substrates. [Copyright &y& Elsevier]

Abstract: In this study, organic–inorganic hybrid perovskite multiple quantum wells (PbI QWs) embedded in porous anodic alumina (PAA) thin films on glass and aluminum substrates are investigated in detail. The pore height and diameter of the nanoscale structure of porous anodic alumina (PAA) film produced by the anodization technique are controllable. The synthesized films are characterized morphologically using the atomic force microscopy (AFM). Scanning electron microscopy (SEM) study showed granular surface. The structural and optical properties were investigated by X-ray diffraction (XRD), photoluminescence (PL) and UV–Vis–NIR spectrophotometer. The effect of the two different substrates on the impregnation of the PbI QW in the PAA is presented. Both PL and AFM studies show a better penetration of the PbI QW in the case of the Al substrate providing a wider pore diameter. Remarkable enhancement of quantum confinement is demonstrated. [Copyright &y& Elsevier]

Abstract: The pore height and diameter of the nanoscale structure of porous anodic alumina (PAA) film produced by the anodization technique are controllable. The structures can be applied for the fabrication of visible spectral range optical devices. In this study we characterized the luminescence properties of self-ordered PAA films evaporated onto silicon substrates. Anomalous luminescence properties produced by carrier confinement were observed in PAA films fabricated with the introduction of oxalic acid electrolytes during the anodization process. The recombination mechanisms were characterized by measuring the temperature-dependent photoluminescence (PL) spectra. The PL spectra of PAA films show an asymmetrical luminescence profile in the blue emission region. The Gaussian function divides these into two subbands. The subbands originate from two different kinds of oxygen-deficient defect centers, namely, F+ (oxygen vacancy with only one electron) and F (oxygen vacancy with two electrons) centers. The F centers are densest at the surface but show a gradual decrease with an increase in the pore wall depth and electrolyte concentration. However, the reverse trend is observed for the F+ centers. In strong contrast to the commonly expected trend of a uniform reduction in non-radiative recombination with decreasing lattice temperature, we observed an anomalous low-temperature PL growth and decline between the F and F+ centers. Theoretical models corroborate the anomalous temperature behavior. All the calculations are in agreement with the experimental observations. [Copyright &y& Elsevier]

Abstract: An enzyme-free amperometric glucose sensor of gold nanoparticle-constituted nanotube array electrode is presented. The resulted gold nanotube array electrode with significantly enhanced surface roughness shows prominent catalytic activity toward the electrooxidation of glucose in a pH 7.4 phosphate buffer (PBS) solution and thus can be used to individually or simultaneously determine glucose and the common interfering molecule of ascorbic acid (AA). In the case of glucose detection, the amperometric responses show a linear relationship to glucose concentration in the range of 1mM–42.5mM with a detection limit down to 10μM. The present non-enzymatic glucose electrochemical biosensor shows a good stability and reproducibility. [Copyright &y& Elsevier]

The effect of nanoscale patterning using a self-organized porous anodic alumina (PAA) mask on the electrical properties of ohmic and Schottky contacts to n-GaN was investigated with the aim of evaluating this approach as a method for reducing the specific contact resistance of ohmic contacts to GaN. The electrical characteristics of contacts to these nanopatterned GaN samples were compared with contacts to planar, chemically prepared ("as-grown") GaN samples and reactive ion etched (RIE) GaN films without any patterning. The specific contact resistivities to unintentionally doped n-GaN using a Ti/Al bilayer metallization were determined to be 7.4 x 10-3 Ω cm² for the RIE sample and 7.0 x 10-4 Ω cm² for the PAA patterned sample. Schottky metal contacts with Pt and Ni were prepared on the three samples to validate the effects of RIE and nanopatterning on electrical behavior. The effective barrier height was decreased and the reverse current was increased significantly in the PAA patterned sample. The radius of curvature of the nanoscale corrugation in the patterned interface was smaller than the depletion width. The reduction of the depletion width at sharp corners enhanced the local tunneling current, reducing the specific contact resistivity and decreasing the effective barrier height. These results suggest that nanopatterning with PAA on GaN can significantly lower the contact resistance. [ABSTRACT FROM AUTHOR]

Abstract: A novel three-dimensionally structured electrode has been fabricated by supporting Pd on carbonized and pulverized porous anodic alumina (PAA) for alcohol oxidation in alkaline media. A four-step process is used to prepare the Pd on carbonized and pulverized PAA (Pd/CPAA) electrocatalysts. The properties of the Pd/CPAA electrocatalytic material are characterized by SEM and electrochemical techniques. The results show that the activities of alcohol oxidation on Pd/CPAA electrocatalyst are higher than that on Pd/C electrocatalyst. The experiments also demonstrate that the beneficial effect of CPAA is more than an increased surface area of the supporting materials. Such materials could be potentially used as an electrocatalyst support in liquid fuel cells, sensors and metal–air batteries. [Copyright &y& Elsevier]

Over the past few years, researchers have made numerous breakthroughs in the field of aluminum anodizing and faced the problem of the lack of adequate theoretical models for the interpretation of some new experimental findings. For instance, spontaneously formed anodic alumina nanofibers and petal-like patterns, flower-like structures observed under AC anodizing conditions, and hierarchical pores whose diameters range from several nanometers to sub-millimeters could be explained neither by the classical field-assisted dissolution theory nor by the plastic flow model. In addition, difficulties arose in explaining the basic indicators of porous film growth, such as the nonlinear current–voltage characteristics of electrochemical cells or the evolution of hexagonal pore patterns at the early stages of anodizing experiments. Such a conceptual crisis resulted in new multidisciplinary investigations and the development of novel theoretical models, whose evolution is discussed at length in this review work. The particular focus of this paper is on the recently developed electroconvection-based theories that allowed making truly remarkable advances in understanding the porous anodic alumina formation process in the last 15 years. Some explanation of the synergy between electrode reactions and transport processes leading to self-organization is provided. Finally, future prospects for the synthesis of novel anodic architectures are discussed. [ABSTRACT FROM AUTHOR]

A robust and reliable method for fabricating porous anodic alumina (PAA)-based distributed Bragg reflectors (DBRs), operating in mid-infrared (MIR) spectral region, is presented. The method relies on application of high (UH) and low (UL) voltage pulse sequence repeated in cycles. PAA-based DBR consists of alternating high-(dH) and low-porosity (dL) layers translated directly into periodically varied refractive index. Two anodization modes were used: time- and charge density-controlled mode. The former generated dH + dL pairs with non-uniform thickness (∆d) and effective refractive index (∆neff). It is supposed, that owing to a compensation effect between the ∆d and ∆neff, the photonic stopbands (PSBs) were symmetrical and intensive (transmittance close to zero). Under the charge density-controlled mode dH + dL pairs of uniform thickness were formed. However, the remaining ∆neff provided an asymmetrical broadening of PSBs. Furthermore, it is demonstrated that the spectral position of the PSBs can be precisely tuned in the 3500–5500 nm range by changing duration of voltage pulses, the amount of charge passing under subsequent UH and UL pulses, and by pore broadening after the electrochemical synthesis. The material can be considered to be used as one-dimensional transparent photonic crystal heat mirrors for solar thermal applications. [ABSTRACT FROM AUTHOR]

In this work, the influence of various electrochemical parameters on the production of porous anodic alumina (PAA)-based DBRs (distributed Bragg reflector) during high-temperature-pulse-anodization was studied. It was observed that lowering the temperature from 30 to 27 °C brings about radical changes in the optical performance of the DBRs. The multilayered PAA fabricated at 27 °C did not show optical characteristics typical for DBR. The DBR performance was further tuned at 30 °C. The current recovery (iamax) after application of subsequent UH pulses started to stabilize upon decreasing high (UH) and low (UL) voltage pulses, which was reflected in a smaller difference between initial and final thickness of alternating dH and dL segments (formed under UH and UL, respectively) and a better DBR performance. Shortening UH pulse duration resulted in a progressive shift of photonic stopbands (PSBs) towards the blue part of the spectrum while keeping intensive and symmetric PSBs in the NIR-MIR range. Despite the obvious improvement of the DBR performance by modulation of electrochemical parameters, the problem regarding full control over the homogeneous formation of dH+dL pairs remains. Solving this problem will certainly lead to the production of affordable and efficient PAA-based photonic crystals with tunable photonic properties in the NIR-MIR region. [ABSTRACT FROM AUTHOR]

In this work, the influence of a wide range anodizing temperature (5–30 °C) on the growth and optical properties of PAA-based distributed Bragg reflector (DBR) was studied. It was demonstrated that above 10 °C both structural and photonic properties of the DBRs strongly deteriorates: the photonic stop bands (PSBs) decay, broaden, and split, which is accompanied by the red shift of the PSBs. However, at 30 °C, new bands in transmission spectra appear including one strong and symmetric peak in the mid-infrared (MIR) spectral region. The PSB in the MIR region is further improved by a small modification of the pulse sequence which smoothen and sharpen the interfaces between consecutive low and high refractive index layers. This is a first report on PAA-based DBR with a good quality PSB in MIR. Moreover, it was shown that in designing good quality DBRs a steady current recovery after subsequent application of high potential (UH) pulses is more important than large contrast between low and high potential pulses (UH-UL contrast). Smaller UH-UL contrast helps to better control the current evolution during pulse anodization. Furthermore, the lower PSB intensity owing to the smaller UH-UL contrast can be partially compensated by the higher anodizing temperature. [ABSTRACT FROM AUTHOR]

Multisegmented metallic nanorods (MS-M-NRs) have attracted increasing attention thanks to their integrated structures and complex functions. The integration of nanoscale segments in 1D enables maximum exposure of each segment and enhanced interaction between adjacent segments. Such structural integration will induce functional complexity in the nanorods, leading to superior properties for the individual components. Herein, recent progress on the development of MS-M-NRs is reviewed. Their precise fabrication, nanoscale manipulation, and subwavelength imaging, as well as simultaneous manipulation and imaging are discussed, respectively. Specifically, precise fabrication of MS-M-NRs focuses on porous anodic alumina (PAA) templated electrodeposition, which enables sub-10 nm growth of the segments and their interfaces/fronts. Nanoscale manipulation of MS-M-NRs introduces the fundamental methods that are employed for delicate movement control on the nanorods through internal or external stimulations. Subwavelength imaging of MS-M-NRs highlights the achievements on identification and location of constituent nanoscale segments/gaps based on their differences and interactions. Simultaneous manipulation and imaging of MS-M-NRs addresses the significance and potential applications of the nanorods with magnetic-plasmonic dual modulation. The development of MS-M-NRs will greatly contribute to materials science and nanoscience/nanotechnology., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)