Analytical and Experimental Investigations of Electromagnetic Field Enhancement Among Nanospheres With Varying Spacing

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Li-Hsin Han ◽  
Wei Wang ◽  
Yalin Lu ◽  
R. J. Knize ◽  
Kitt Reinhardt ◽  
...  
Keyword(s):  
Absorption Spectra ◽  
Scattering Theory ◽  
Near Infrared ◽  
Field Enhancement ◽  
Infrared Region ◽  
Mie Scattering ◽  
Interparticle Spacing ◽  
Experimental Investigations ◽  
Gold Nanospheres ◽  
Peak Broadening

A modified Mie scattering theory was used to calculate the enhancement of electromagnetic (EM) field between gold nanospheres. The simulation result showed that the density of EM-energy in the space between neighboring nanospheres increases drastically as the interparticle space decreases. Simulated absorption-spectra also showed a peak-shifting from the visible to the infrared region when decreasing the nanosphere spacing. We used our previous experiment to verify the analytical results; the experiment was conducted by using a photodeformable microshell, which was coated with gold nanospheres. Made of photoshrinkable azobenzene polyelectrolytes, the microshells supported the gold nanospheres and gave the tunability of the interparticle spacing among the nanospheres. Upon irradiation of ultraviolet light, the microshells shrank and reduced the interparticle space. The absorption-spectra of the gradually shrinking microshells showed significant changes; a peak-broadening from the visible to the near-infrared region and a drastically enhanced water-absorption were observed in the experimental spectra. The experimental results confirmed the analytical analysis based on the modified scattering theory.

scholarly journals Towards rational design and optimization of near-field enhancement and spectral tunability of hybrid core-shell plasmonic nanoprobes

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Debadrita Paria ◽  
Chi Zhang ◽  
Ishan Barman
Keyword(s):  
Single Molecule ◽  
Rational Design ◽  
Near Infrared ◽  
Theoretical Calculations ◽  
Near Field ◽  
Field Enhancement ◽  
Infrared Region ◽  
Core Shell ◽  
Optimization Strategy ◽  
Design And Optimization

Abstract In biology, sensing is a major driver of discovery. A principal challenge is to create a palette of probes that offer near single-molecule sensitivity and simultaneously enable multiplexed sensing and imaging in the “tissue-transparent” near-infrared region. Surface-enhanced Raman scattering and metal-enhanced fluorescence have shown substantial promise in addressing this need. Here, we theorize a rational design and optimization strategy to generate nanostructured probes that combine distinct plasmonic materials sandwiching a dielectric layer in a multilayer core shell configuration. The lower energy resonance peak in this multi-resonant construct is found to be highly tunable from visible to the near-IR region. Such a configuration also allows substantially higher near-field enhancement, compared to a classical core-shell nanoparticle that possesses a single metallic shell, by exploiting the differential coupling between the two core-shell interfaces. Combining such structures in a dimer configuration, which remains largely unexplored at this time, offers significant opportunities not only for near-field enhancement but also for multiplexed sensing via the (otherwise unavailable) higher order resonance modes. Together, these theoretical calculations open the door for employing such hybrid multi-layered structures, which combine facile spectral tunability with ultrahigh sensitivity, for biomolecular sensing.

Quantitative analysis of hemoglobin oxygenation state of rat brain in situ by near-infrared spectrophotometry

1988 ◽  
Vol 64 (2) ◽  
pp. 796-802 ◽  
Author(s):  
O. Hazeki ◽  
M. Tamura
Keyword(s):  
Absorption Spectra ◽  
Near Infrared ◽  
Infrared Region ◽  
Hemoglobin Content ◽  
Hemoglobin Oxygenation ◽  
Absorbance Changes ◽  
Near Infrared Region ◽  
The Difference ◽  
Difference Absorption ◽  
The Brain

The light in the near-infrared region (700–900 nm) was illuminated on the rat head, and absorption spectra were measured with the transmitted light under various conditions. The absorbance changes less than 780 nm were attributable to hemoglobin in the brain tissue, whereas those greater than 780 nm were associated with both hemoglobin and cytochrome oxidase. The changes of oxy- and total (oxy- plus deoxy-) hemoglobin content in the rat head could be monitored quantitatively by expressions of delta A700--1.20 delta A730 and delta A700--1.52 delta A730, respectively. The oxyhemoglobin content in the tissue was decreased as the O2 tension in inspired gas was lowered. At 10% O2 approximately 50% of hemoglobin was deoxygenated. The total hemoglobin content was increased under anoxic conditions. Inhalation of 5% CO2 and intravenous injection of a Ca2+ blocker nicardipine increased the O2 saturation of hemoglobin in the brain. These conclusions were confirmed by measuring the difference absorption spectra in the near-infrared region.

scholarly journals Giant Second Harmonic Generation Enhancement by Ag Nanoparticles Compactly Distributed on Hexagonal Arrangements

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2394
Author(s):  
Alejandro Gómez-Tornero ◽  
Luisa E. Bausá ◽  
Mariola O. Ramírez
Keyword(s):  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Frequency Conversion ◽  
Near Infrared ◽  
Second Harmonic ◽  
Field Enhancement ◽  
Infrared Region ◽  
Plasmonic Nanostructures ◽  
Harmonic Intensity ◽  
Dielectric Interfaces

The association of plasmonic nanostructures with nonlinear dielectric systems has been shown to provide useful platforms for boosting frequency conversion processes at metal-dielectric interfaces. Here, we report on an efficient route for engineering light–matter interaction processes in hybrid plasmonic-χ(2) dielectric systems to enhance second harmonic generation (SHG) processes confined in small spatial regions. By means of ferroelectric lithography, we have fabricated scalable micrometric arrangements of interacting silver nanoparticles compactly distributed on hexagonal regions. The fabricated polygonal microstructures support both localized and extended plasmonic modes, providing large spatial regions of field enhancement at the optical frequencies involved in the SHG process. We experimentally demonstrate that the resonant excitation of the plasmonic modes supported by the Ag nanoparticle-filled hexagons in the near infrared region produces an extraordinary 104-fold enhancement of the blue second harmonic intensity generated in the surface of a LiNbO3 crystal. The results open new perspectives for the design of efficient hybrid plasmonic frequency converters in miniaturized devices.

The absorption spectra of H2O+and D2O+in the visible and near infrared region

2004 ◽  
Vol 102 (6) ◽  
pp. 611-621 ◽  
Author(s):  
Yujie Gan ◽  
Xiaohua Yang ◽  
Yingchun Guo ◽  
Shenghai Wu ◽  
Wei Li ◽  
...  
Keyword(s):  
Absorption Spectra ◽  
Near Infrared ◽  
Infrared Region ◽  
Near Infrared Region

Visible Luminescence Properties of Sm3+ Doped Magnesium Bismuth Phosphate Glasses

2016 ◽  
Vol 675-676 ◽  
pp. 405-408 ◽  
Author(s):  
Narong Sangwaranatee ◽  
Jakrapong Kaewkhao ◽  
Natthakridta Chanthima
Keyword(s):  
Absorption Spectra ◽  
Near Infrared ◽  
Infrared Region ◽  
Phosphate Glasses ◽  
Excitation Wavelength ◽  
Absorption Bands ◽  
Visible Luminescence ◽  
Yellow Color ◽  
Bismuth Phosphate ◽  
Quenching Method

In this research, the magnesium bismuth phosphate glasses doped with different concentration of Sm2O3 have been prepared using the melt quenching method at 1200 °C. Magnesium bismuth phosphate glasses are clear, homogenous and increased yellow color with increasing the concentration of Sm2O3. Physical and optical properties of glass samples were investigated. The results show that, the density and molar volumes were increased with increasing the concentration of Sm2O3. The absorption spectra in the wavelength range at 200 - 2500 nm was observed. It was found that the absorption bands have nine peaks with corresponding to 401, 439, 472, 945, 1081, 1231, 1378, 1480 and 1533 nm. Absorption bands at 401 and 1231 nm are highest absorption spectra in visible and near infrared region, respectively. For the luminescence spectrum of glass samples has shown four emission transitions at 562 (green), 598 (orange), 664 (red) and 705 nm with excitation wavelength at 401 nm. The wavelength at 401 and 598 nm has shown highest intensity of excitation and emission wavelength, respectively.

Near infrared spectra of some cobalt(II) compounds

1968 ◽  
Vol 21 (7) ◽  
pp. 1775
Author(s):  
DP Graddon ◽  
GM Mockler
Keyword(s):  
Absorption Band ◽  
Absorption Spectra ◽  
Metal Atom ◽  
Infrared Spectra ◽  
Near Infrared ◽  
Infrared Region ◽  
Absorption Bands ◽  
Heterocyclic Base ◽  
Near Infrared Spectra ◽  
Near Infrared Region

Absorption spectra of compounds CoX2B2 and CoX2B4 (X = Cl, Br, I, or NCS; B = a heterocyclic base) have been obtained by reflectance and in solution in the near infrared region between 1000 and 2000 mμ. The spectra are characteristic of the stereochemistry of the metal atom: octahedral compounds have a single absorption band near 1100 mμ, e < 10; tetrahedral compounds have three overlapping absorption bands near 1100,1400, and 1700 mp, 30 < < 150. Comparisons are made with previously observed spectra of octahedral and tetrahedral species of the types CoL2+6 and CoX2-4.

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