Red-shift Of Resonance Peak Research Articles

Phonons correction of the energy and photoionization cross section in polar semiconductors and hollow nanoparticles

Abstract

Near-field radiative heat transfer in multilayered graphene system considering equilibrium temperature distribution.

In the present work, the near-field radiative heat transfer of a multilayered graphene system is investigated within the framework of the many-body theory. For the first time, the temperature distribution corresponding to the steady state of the system is investigated. Unique temperature steps are observed near both boundaries of the system, especially in the strong near-field regime. By utilizing the effective radiative thermal conductance, the thermal freedom of heat flux in different regions of the system is analyzed quantitatively, and the cause of various temperature distributions is explained accordingly. To characterize the heat transfer ability of the whole system, we evaluate the system with two heat transfer coefficients (HTC), transient heat transfer coefficient (THTC), and steady heat transfer coefficient (SHTC). A unique many-body enhancement is observed, which causes a red-shift of resonance peak corresponding to graphene surface plasmon polaritons. Furthermore, a three-body enhancement of SHTC emerges thanks to the relay effect and the complexity of the system. The regime of heat transport can be tuned by changing the chemical potentials of graphene and undergoes a transition from diffusive to quasi-ballistic transport in the strong near-field regime.

Growth and characterization of Au nanoparticles embedded In2O3 composite films

Au nanoparticles embedded In2O3 thin films (In2O3:Au) were grown by DC reactive sputtering method in three different target configurations. Presence of Au in In2O3 matrix was confirmed by glancing angle X-ray diffraction (GXRD) and transmission electron microscopy (TEM). Crystallite sizes of Au were obtained by Debye-Scherrer formula from GXRD data. Localized surface plasmon resonance was observed for In2O3:Au samples from optical absorption measurement at peak value of ~550nm and inferred red shift of resonance peak towards the increasing crystallite size. Rutherford backscattering spectrometry (RBS) studies of selected samples on Si substrate showed minor In diffusion and absence of Au diffusion into the Si substrate. X-ray photoelectron spectroscopy (XPS) studies revealed that the chemical state of Au is neutral. The samples with high Au content exhibited persistent photoconductivity due to the sub band gap absorption indicating the introduction of sub band gap trap levels in In2O3.

Research on the glucose-sensing characteristics of gold microparticle-doped silica microfiber based on refractive index measurement

A gold microparticle-doped silica microfiber was proposed in this paper. The refractive index sensing properties were experimentally and calculatedly demonstrated by transmission spectra using glucose solution with different concentrations, where the redshift of resonance peaks has been analyzed for the concentrations range from 0 to 0.282 mol/L. The experimental results indicate the detection limit of 53.2 μmol/L. The sensing characteristics of pure silica microfiber were experimentally and calculatedly explored to demonstrate the impact of the gold particles introduction on the sensitivity enhancement. The miniature geometry will prompt the development of the novel wearable or implantable glucose sensor.

Fano resonance generated by magnetic scatterer in micro metal slit

A micro metal slit/magnetic scatterer structure is proposed to generate electromagnetic Fano resonance. The magnetic scatterer is formed by infinite long split cylinder resonator array. The analytical transmissivity formulas are deduced from Maxwell electromagnetic theory and the Fano resonance transmission is achieved by the theoretical calculations. The enhancement of environment refractive index leads to an ultrasensitive and linear red shift of resonance peak in the THz range.

A label-free single photonic quantum well biosensor based on porous silicon for DNA detection

The single photonic quantum well (PQW) structures are successfully fabricated on p-type silicon wafer by electrochemical etching process, and are used for DNA detection firstly. The red shift of resonance peak is caused by the changing refractive index of PSi layer, which results from coupling of organic molecules into pores. When the porous silicon (PSi) based single PQW biosensors are immersed in complementary deoxyribonucleic acid (DNA) with different concentrations ranging from 0.625 μM to 10.000 μM, a good linear relationship is observed between the red shift of resonance peak and the complementary DNA concentration. Experimental results show that the detection sensitivity of PSi-based single PQW biosensors is 3.04 nm/μM with a detection limit of 32 nM for 16-base pair DNA oligonucleotides.