scholarly journals Adiabatic mode transformation in width-graded nano-gratings enabling multiwavelength light localization

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Moein Shayegannia ◽  
Arthur O. Montazeri ◽  
Katelyn Dixon ◽  
Rajiv Prinja ◽  
Nastaran Kazemi-Zanjani ◽  
...  
Keyword(s):  
Multispectral Imaging ◽  
Groove Depth ◽  
Surface Enhanced Raman Spectroscopy ◽  
Fine Tuning ◽  
Mode Transformation ◽  
Resonance Modes ◽  
Light Localization ◽  
Metal Insulator Metal ◽  
Surface Enhanced Raman ◽  
Adiabatic Mode

AbstractWe delineate the four principal surface plasmon polariton coupling and interaction mechanisms in subwavelength gratings, and demonstrate their significant roles in shaping the optical response of plasmonic gratings. Within the framework of width-graded metal–insulator-metal nano-gratings, electromagnetic field confinement and wave guiding result in multiwavelength light localization provided conditions of adiabatic mode transformation are satisfied. The field is enhanced further through fine tuning of the groove-width (w), groove-depth (L) and groove-to-groove-separation (d). By juxtaposing the resonance modes of width-graded and non-graded gratings and defining the adiabaticity condition, we demonstrate the criticality of w and d in achieving adiabatic mode transformation among the grooves. We observe that the resonant wavelength of a graded grating corresponds to the properties of a single groove when the grooves are adiabatically coupled. We show that L plays an important function in defining the span of localized wavelengths. Specifically, we show that multiwavelength resonant modes with intensity enhancement exceeding three orders of magnitude are possible with w < 30 nm and 300 nm < d < 900 nm for a range of fixed values of L. This study presents a novel paradigm of deep-subwavelength adiabatically-coupled width-graded gratings—illustrating its versatility in design, hence its viability for applications ranging from surface enhanced Raman spectroscopy to multispectral imaging.

scholarly journals Integrating liquid chromatography mass spectrometry into an analytical protocol for the identification of organic colorants in Japanese woodblock prints

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Marc Vermeulen ◽  
Diego Tamburini ◽  
Emily M. K. Müller ◽  
Silvia A. Centeno ◽  
Elena Basso ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Raman Spectroscopy ◽  
Liquid Chromatography ◽  
Multispectral Imaging ◽  
Surface Enhanced Raman Spectroscopy ◽  
Carthamus Tinctorius ◽  
Edo Period ◽  
Woodblock Prints ◽  
Surface Enhanced Raman ◽  
Japanese Woodblock Prints

AbstractThree Japanese woodblock prints from the Edo period (1603–1868) underwent a scientific investigation with the aim of understanding the changes in the colorants used in Japanese printing techniques. A multi-analytical approach was adopted, combining non-invasive techniques, such as fiber optic reflectance spectroscopy (FORS), Raman spectroscopy, multispectral imaging (MSI), and macro X-ray fluorescence (MA-XRF) with minimally invasive surface-enhanced Raman spectroscopy (SERS). The results enabled many of the pigments to be identified and their distribution to be studied, apart from two shades of purple of organic composition. Consequently, the potential of high-pressure liquid chromatography tandem mass spectrometry (HPLC–MS/MS) was explored for the first time with application to Japanese woodblock prints. The intrinsic sensitivity of the instrument and an effective extraction protocol allowed us to identify a mixture of dayflower (Commelina communis) blue and safflower (Carthamus tinctorius) red in purple samples constituted of 2–3 single fibers. In addition to the innovative integration of MA-XRF and HPLC–MS/MS to investigate these delicate artworks, the study concluded on the use of traditional sources of colors alongside newly introduced pigments in late Edo-period Japan. This information is extremely important for understanding the printing practices, as well as for making decisions about display, conservation, and preservation of such artworks.

scholarly journals Resonant Terahertz Light Absorption by Virtue of Tunable Hybrid Interface Phonon–Plasmon Modes in Semiconductor Nanoshells

2019 ◽  
Vol 9 (7) ◽  
pp. 1442
Author(s):  
Denis Nika ◽  
Evghenii Pokatilov ◽  
Vladimir Fomin ◽  
Josef Devreese ◽  
Jacques Tempere
Keyword(s):  
Light Absorption ◽  
Surface Enhanced Raman Spectroscopy ◽  
Absorption Peak ◽  
Fine Tuning ◽  
Fourfold Increase ◽  
Peak Intensity ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Hybrid Interface ◽  
Plasmon Modes

Metallic nanoshells have proven to be particularly versatile, with applications in biomedical imaging and surface-enhanced Raman spectroscopy. Here, we theoretically demonstrate that hybrid phonon-plasmon modes in semiconductor nanoshells offer similar advantages in the terahertz regime. We show that, depending on tm,n,nhe doping of the semiconductor shells, terahertz light absorption in these nanostructures can be resonantly enhanced due to the strong coupling between interface plasmons and phonons. A threefold to fourfold increase in the absorption peak intensity was achieved at specific values of electron concentration. Doping, as well as adapting the nanoshell radius, allowed for fine-tuning of the absorption peak frequencies.

Bacterial detection and differentiation via direct volatile organic compound sensing with surface enhanced Raman spectroscopy

2017 ◽  
Author(s):  
Caitlin S. DeJong ◽  
David I. Wang ◽  
Aleksandr Polyakov ◽  
Anita Rogacs ◽  
Steven J. Simske ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Bacterial Infections ◽  
Direct Detection ◽  
Point Of Care ◽  
Surface Enhanced Raman Spectroscopy ◽  
E Coli ◽  
Recent Emergence ◽  
Surface Enhanced ◽  
Volatile Organic ◽  
Surface Enhanced Raman

Through the direct detection of bacterial volatile organic compounds (VOCs), via surface enhanced Raman spectroscopy (SERS), we report here a reconfigurable assay for the identification and monitoring of bacteria. We demonstrate differentiation between highly clinically relevant organisms: <i>Escherichia coli</i>, <i>Enterobacter cloacae</i>, and <i>Serratia marcescens</i>. This is the first differentiation of bacteria via SERS of bacterial VOC signatures. The assay also detected as few as 10 CFU/ml of <i>E. coli</i> in under 12 hrs, and detected <i>E. coli</i> from whole human blood and human urine in 16 hrs at clinically relevant concentrations of 10<sup>3</sup> CFU/ml and 10<sup>4</sup> CFU/ml, respectively. In addition, the recent emergence of portable Raman spectrometers uniquely allows SERS to bring VOC detection to point-of-care settings for diagnosing bacterial infections.

Graphene and Graphene Oxide Applications for SERS Sensing and Imaging

2019 ◽  
Vol 26 (38) ◽  
pp. 6878-6895 ◽  
Author(s):  
Anna Jabłońska ◽  
Aleksandra Jaworska ◽  
Mateusz Kasztelan ◽  
Sylwia Berbeć ◽  
Barbara Pałys
Keyword(s):  
Graphene Oxide ◽  
Surface Enhanced Raman Spectroscopy ◽  
Biological Species ◽  
Chemical Mechanism ◽  
Aromatic Molecules ◽  
Sers Enhancement ◽  
Reduced Graphene ◽  
Surface Enhanced Raman ◽  
Active Nanoparticles ◽  
Fluorescence Quencher

: Surface Enhanced Raman Spectroscopy (SERS) has a long history as an ultrasensitive platform for the detection of biological species from small aromatic molecules to complex biological systems as circulating tumor cells. Thanks to unique properties of graphene, the range of SERS applications has largely expanded. Graphene is efficient fluorescence quencher improving quality of Raman spectra. It contributes also to the SERS enhancement factor through the chemical mechanism. In turn, the chemical flexibility of Reduced Graphene Oxide (RGO) enables tunable adsorption of molecules or cells on SERS active surfaces. Graphene oxide composites with SERS active nanoparticles have been also applied for Raman imaging of cells. This review presents a survey of SERS assays employing graphene or RGO emphasizing the improvement of SERS enhancement brought by graphene or RGO. The structure and physical properties of graphene and RGO will be discussed too.

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