Localized Surface Plasmon Resonance Research Articles

Polyvinyl alcohol assisted citrate based reduction of gold(III) ions: Theoretical design and experimental study on green synthesis of spherical and biocompatible gold nanoparticles

In this study, we demonstrate the synthesis of small gold nanoparticles (typically 8-10 nm) through a green synthesis approach. This method involves utilizing chloroauric acid as the gold precursor, trisodium citrate as a mild reducing and co-capping agent, and polyvinyl alcohol (PVA), as a co-capping and shape-directing agent. This novel synthesis method stands alone as a protocol that involves just mixing the reagents at room temperature and allowing the reaction to proceed at ambient temperature without any disturbance. In the absence of PVA, spherical particles are not formed and the reaction mixture slowly turns black followed by precipitation.The synthesis process was meticulously tracked using time-resolved monitoring of the growth of the localized surface plasmon resonance (LSPR) by UV-vis spectroscopy and transmission electron microscopy. The as-prepared colloidal gold solution was bright red, attributed to the small size (≤ 10 nm) and spherical geometry of nanoparticles. This colloidal solution could be stored indefinitely at room temperature without precipitation or a change in its absorption profile. The nanoparticles remained stable in adverse conditions such as 100 mM NaCl solution, 1×PBS and cell culture medium. Additionally, they could be easily loaded with drugs like doxorubicin by adsorption. The particles were thoroughly characterized using a range of techniques, including UV-vis spectroscopy, attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), high-resolution transmission electron microscopy (HRTEM), hyperspectral-enhanced dark field microscopy (HEDFM), dynamic light scattering (DLS), and X-ray photoelectron spectroscopy (XPS). Cell viability tests conducted on 2D cell lines and 3D spheroids revealed negligible toxicity even at high concentrations. Furthermore, we demonstrate that an advanced version of conventional diffusion-limited aggregation (DLA) schemes, which allows individual clusters to move freely within a domain to form larger aggregates, can effectively replicate the intricate interactions between chloroauric acid, trisodium citrate, and PVA, the agents involved in the synthesis of gold nanoparticles.

Incorporation of Gold Nanoparticle into ZnO Electron Transport Layer to Improve Performance of Hybrid Bulk Heterojunction Solar Cell

Abstract We have investigated the effect of localized surface plasmon resonance (LSPR) from gold nanoparticles incorporated into the electron transport layer (ETL) of zinc oxide (ZnO) on charge carrier transport in order to improve the performance of inverted hybrid bulk-heterojunction solar cells. Synthesis of gold nanoparticles capped by 3-mercaptopropionic acid (AuMPA) and oleylamine (AuOA) was carried out by use of the reduction method and the fabrication of solar cell device with the configuration of ITO/ZnO:AuNPs/P3HT:PCBM/PEDOT:PSS/Ag was done by spin coating and thermal evaporation techniques. The absorbance spectra show a plasmonic peak of AuMPA in solution at 521 nm, while AuOA has a plasmonic peak at 531 nm, with both solutions showing a red-wine color. In our investigation, the incorporation of AuMPA about 2.65wt% or AuOA about 3.5 wt% in the ZnAc solution is quite stable. With the addition of 1.77 wt% AuMPA, the fabricated devices show a significant improvement at short circuit condition (JSC) from 46.67 mA/cm2 to 83.11 mA/cm2, resulting in an increase in power conversion efficiency (PCE) from 5.64% to 9.00% under the illumination of 100 mW/cm2 simulated solar irradiation. While the AuOA addition of 2.65 wt%, the JSC increased from 22.67 mA/cm2 to 44.12 mA/cm2 along with an improvement of PCE from 2.71% to 5.32%. The experiment results suggest that the electron mobility or charge carrier transport to the indium tin oxide (ITO) cathode is improved by the local electric field enhancement around the zinc oxide (ZnO) electron transport layer due to the effect of gold nanoparticles (AuNPs).

Exploring the thermal and optical characteristics of Ti3C2 MXene for enhanced photothermal conversion

Ti3C2 MXene, a member of the two-dimensional (2D) transition metal carbides family, has garnered significant attention for its exceptional photothermal properties. To understand the mechanistic underpinnings of this feature, we conducted a comprehensive first-principles density functional theory analysis. This study was aimed at investigating the electronic band structure and vibrational characteristics of Ti3C2 MXene to unravel its microscopic process of photothermal conversion. After obtaining its optical and thermal properties, the process by which the material moves from light absorption to heat release is elucidated. The presence of localized surface plasmon resonance (LSPR) effects in Ti3C2 is proved by Finite-difference time-domain (FDTD) simulations. The synergy between the high thermal conductivity network in the Ti layers and the LSPR phenomenon is believed to be responsible for the superior photothermal conversion capabilities. This investigation enhances the understanding of the intrinsic properties of Ti3C2 MXene, confirming its status as an ultrahigh photothermal conversion material.

Unveiling the potential: Gallium-doped zinc oxide/silver-nanoparticles/glass structure for superior anode performance in polymer light-emitting diodes

This study examines the effectiveness of gallium-doped zinc oxide (GZO) combined with silver nanoparticles (Ag-NPs) on glass substrates as anodes for polymer light-emitting diodes (PLEDs). The proposed GZO/Ag-NPs/glass structure achieved superior electrical and optical properties, with a peak luminance of 5834 cd/m2 and an average current efficiency of 1.91 cd/A, significantly outperforming the conventional GZO/Ag-NPs/GZO/glass anode. The GZO/Ag-NPs/glass anode enhanced electroluminescence intensity by 379 % compared to the GZO/glass anode, while the GZO/Ag-NPs/GZO/glass anode showed a 196 % enhancement. This highlights the potential for improved PLED performance through enhanced anode conductivity and localized surface plasmon resonance effects.

Highly sensitive, reproducible, and stable core–shell MoN SERS substrate synthesized via sacrificial template method

Molybdenum nitride is a promising candidate for surface-enhanced Raman scattering (SERS) substrates due to its high conductivity, surface plasmon resonance, and chemical stability. Core-shell structures possess unique physical and chemical properties, such as high-volume ratio, low density, short diffusion length, and high load-bearing capacity, making them favorable for SERS applications. In this research, core–shell MoO3 is first synthesized as a precursor oxide using a sacrificial template method, and core–shell MoN microspheres are successfully prepared via subsequent nitriding. As a representative transition metal nitride, the obtained core–shell MoN nanospheres show strong localized surface plasmon resonance and SERS effects. Using these MoN microspheres as Raman substrates allows a range of highly targeted compounds to be accurately detected, and the detection limits for this non-precious-metal substrate morphology are exceptionally high, reaching 10−10 M. In addition, MoN nanospheres exhibit excellent resistance to acid–base corrosion, oxidation, and radiation, thus rendering them suitable for use as substrates in harsh environments.

Multifunctional 1–octadecanol/expanded graphite/Fe3O4 composite phase change materials with effective solar–to–thermal and magnetic–to–thermal conversion and storage

Composite phase change materials (CPCMs) with multifunctional thermal conversion and storage abilities have demonstrated exceptional properties for diverse energy storage applications recently; however, these composite materials often encounter limitations of low heat storage capacity and high cost. In this study, novel 1–octadecanol (OD)/expanded graphite (EG)/Fe3O4 CPCMs were facilely prepared and characterized for multifunctional thermal conversion and storage properties. The composites showed excellent thermal energy storage capacities, reaching 185.5 J/g at 80 % OD accompanied by high crystallization fractions of above 95 %. In addition, they exhibited great thermal conductivities, excellent leakage resistance, thermal stability, and reliability. Under simulated solar irradiation, the prepared OD/EG/Fe3O4 CPCMs exhibited a rapid temperature increase from 34 to 70 °C, achieving solar–to–thermal conversion efficiency of 80.2–90.5 %. This behavior can be attributed to its ability to capture and convert photons into thermal energy, facilitated by the synergistic effects of the conjugated double–bond system of EG and localized surface plasmon resonance of Fe3O4 nanoparticles. Furthermore, the prepared OD/EG/Fe3O4 CPCMs exhibited superparamagnetic properties, accelerating their temperatures from 32 °C to 88 °C within 11–23 s when subjected to an alternating magnetic field. This demonstrates magnetic–to–thermal conversion and storage ability. These findings highlight the potential of OD/EG/Fe3O4 CPCMs as promising and cost–effective materials for various practical thermal storage applications.

Surface Modification of Gold Nanorods: Multifunctional Strategies and Application Prospects.

Gold nanorods (AuNRs), as an important type of gold nanomaterials, have attracted much attention in the nano field. Compared with gold nanoparticls, AuNRs have broader application potential due to their tunable localized surface plasmon resonance properties and anisotropic shapes. Yet, conventional synthesis methods using surfactants have limited the use of AuNRs in a variety of fields such as biomedical applications, plasma-enhanced fluorescence, optics and optoelectronic devices. To solve this problem and improve the stability and biocompatibility of AuNRs, researchers in recent years have used surface modification and functionalization to modify AuNRs, among which the introduction of organic ligands to prepare organic/gold hybrid nanorods has become an effective strategy. Organic materials have better toughness and easy processing, and by introducing organic ligands into the surface of AuNRs, the molecular-level composite of organic and inorganic materials can be realized, thus obtaining hybrid nanorods with excellent properties. This paper reviews the research progress of hybrid nanocomposites, and introduces the synthesis methods of AuNRs and the development of surface ligand modification, then summaries the applications of a wide variety of ligands. Also, the advantages and disadvantages of different ligands and their roles in further self-assembly processes are discussed.

Chemically bonded nonmetallic LSPR S-scheme hollow heterostructure for boosting photocatalytic performance

The light absorption, mass transfer, and charges separation are essential to the efficiency of photocatalytic reaction, but constructing photocatalyst with the three excellent properties is still challenging. Herein, the interfacial Mo-S bonds and oxygen vacancy synchronously decorated MoO3-x/Zn3In2S6 (MoO3-x/ZIS) heterostructure was rationally designed and synthesized. The oxygen-defective MoO3-x nanotubes showed hollow structure and local surface plasmonic resonance (LSPR) effect, which improved mass transfer and solar light absorption. Besides, the built-in electric field and interfacial Mo-S bond provided endogenetic impetus and channels for rapid photoexcited charge carriers transfer and separation. The photocatalytic hydrogen (H2) evolution and hydrogen peroxide (H2O2) production on optimal MoO3-x/ZIS composite were 17.34 and 4.47 mmol g−1 h−1, respectively. The apparent quantum efficiency of MoO3-x/ZIS for H2 evolution at 400 nm was about 13.92 %, which was 8.09 times higher than that of ZIS. Moreover, the MoO3-x/ZIS also displayed excellent activities on the selective 5-hydroxymethylfurfural dehydrogenation. The in-situ X-ray photoelectron spectroscopy, electron paramagnetic resonance, in-situ selective photodeposition, and density functional theory calculation confirmed the S-scheme charge transfer pathway between MoO3-x and ZIS. This study provides an effective avenue for designing multifunctional photocatalysts based on the synergistic effects of chemically bonded S-scheme heterostructure and nonmetallic LSPR effect.

Suppressed recombination of a flexible TiO2 nanowires photoanode by coupling of plasmonic Ag nanoparticles in the photoelectrochemical ultraviolet photodetector

The noble metal nanoparticles can improve the efficiency of photoelectric conversion via enhancement of light harvesting for the localized surface plasmon resonance (LSPR) effect. Here, TiO2 nanowires were constructed on carbon fiber cloth as a flexible photoanode for photoelectrochemical (PEC) ultraviolet (UV) photodetector. By decorated noble metal Ag nanoparticles on TiO2 nanowires, the photocurrent was improved from 35.9 μA cm−2 to 268.4 μA cm−2, and the rise and decay time were increased by 0.14 s and 0.12 s, respectively. Moreover, the recombination of photon-generated electrons and holes was also decreased in photoanode due to the Schottky barrier between Ag and TiO2. This work provided an approach to promote the performances of the PEC UV photodetector.

Synergistic Effect Between 0D CQDs and 2D MXene to Enhance the Photothermal Conversion of Hydrogel Evaporators for Efficient Solar Water Evaporation, Photothermal Sensing and Electricity Generation.

Solar-powered interfacial water evaporation is a promising technique for alleviating freshwater stress. However, the evaporation performance of solar evaporators is still constrained by low photothermal conversion efficiency and high water evaporation enthalpy. Herein, 0D carbon quantum dots (CQDs) are combined with 2D MXene to serve as a hybrid photothermal material to enhance the light absorption and photothermal conversion ability, meanwhile sodium carboxymethyl cellulose (CMC)/polyacrylamide (PAM) hydrogels are used as a substrate material for water transport to reduce the enthalpy of water evaporation. The synergistic effect in 0D CQDs/2D MXene hybrid photothermal materials accelerate the carrier transfer, inducing efficient localized surface plasmon resonance (LSPR) effect. This results in the enhanced photothermal conversion efficiency. The integrated hydrogel evaporators demonstrate a high evaporation rate (1.93 and 2.86kgm-2h-1 under 1 and 2 sunlights, respectively) and low evaporation enthalpy (1485Jg-1). In addition, the hydrogel evaporators are applied for photothermal sensing and temperature difference power generation (TEG). The TEG device presents an efficient output power density (230.7mWm-2) under 1 sunlight. This work provides a feasible approach for regulating and controlling the evaporation performances of hydrogel evaporators, and gives a proof-of-concept for the design of multipurpose solar evaporation systems.

Patterned 3D-graphene for self-powered broadband photodetector

The remarkable ultra-wideband energy capabilities of zero-bandgap two-dimensional (2D) graphene have made it an outstanding material for photon absorption and charge carrier generation across a broad spectrum. However, atomically thick 2D-graphene only exhibits a light absorption efficiency of 2.3%, posing a challenge for graphene-based photodetectors to harness photon energy effectively. This study utilized plasma-enhanced chemical vapor deposition technology and a mask to create in situ patterned 3D-graphene/Si-based Schottky heterojunctions. The porous structure and natural nano-resonant cavities of the 3D-graphene enhanced the probability of light absorption, while the curved and sharp edges and corners of the patterned 3D-graphene concentrated the local electromagnetic field and induced localized surface plasmon resonance. Both theoretical and experimental analyses confirmed the improved light absorption mechanisms and charge transfer of photogenerated carriers under the built-in electric field. The photodetector based on the patterned 3D-graphene/Si Schottky structure exhibits excellent broadband response characteristics spanning from 380 to 1550 nm, with responsivity and specific detectivity of 68.47 A/W and 1.43 × 1012 Jones at a wavelength of 1550 nm. Furthermore, the photodetector demonstrated ultrafast microsecond-level response times (116/120 μs rise/fall times) along with exceptional stability and reliability. The potential applications of as-fabricated photodetector include logic devices such as “AND” and “OR” gates and information encryption. This research holds valuable scientific significance for the design of future optoelectronic devices and provides crucial insights and technical support for developing high-performance Si-based graphene detectors.

Synergistic Coordination and Surface Plasmon Resonance of Quantum Dots in Enhancing Photocatalytic Hydrogen Evolution.

Recent studies have revealed that the integration of metal nanoparticles (NPs) with photocatalysts allows the metal NPs to serve as cocatalysts, significantly enhancing reactant efficiency near nanostructures through the surface plasmon resonance (SPR) effect. On this basis, we synthesized highly reactive FePt quantum dots (FePt QDs) with tailored configurations, manipulating the Pt coordination environment and combining FePt QDs with ultrathin two-dimensional nickel metal-organic layer (Ni-MOL) nanosheets. X-ray absorption fine spectroscopy (XAFS) confirmed the distinctive Pt-Fe configuration after photoactivation. The optimized loading amount of FePt QDs led to a hydrogen evolution reaction (HER) yield of 113 mmol·g-1·h-1 after activation, with the catalyst remaining stable over five cycles. The improved reaction efficiency stemmed from Pt coordination adjustments and a localized SPR effect, supported by ultraviolet-visible (UV-vis), infrared (IR), Raman, and XAFS characterizations. A comparative analysis was conducted with Ni-MOL deposited with platinum NPs, further underscoring the distinct advantages of FePt QDs and corroborating by density functional theory (DFT) calculations, which revealed favorable d-band center properties. These findings offer a promising avenue for the development of highly efficient and stable nanoalloy photocatalysts.

Investigation of methylene blue dye degradation using green synthesized mesoporous silver-titanium

In this study, we synthesized mesoporous silver-titanium (Ag/TiO2) through green synthesis approach using mangosteen pericarp extract, which subsequently can act as both adsorbent and photocatalyst materials. Additionally, we investigated and compared the degradation of methylene blue (MB) using mesoporous Ag/TiO2 under dark conditions, visible light irradiation, and both dark-light conditions to analyze the adsorption-photocatalysis activity. The achieved mesoporous structure in this study offers distinct advantages as an adsorbent. Moreover, the addition of silver (Ag) to titanium dioxide (TiO2) shows promise in enhancing photocatalytic activity in MB degradation, which enhances photocatalytic activity in the visible light region due to its localized surface plasmon resonance (LSPR), which excites more electrons, resulting in increased MB degradation. The highest degradation percentage of 97.08 % was obtained using a dark-light degradation mechanism, demonstrating that the synthesized mesoporous Ag/TiO2 has potential as an effective integrated adsorbent-photocatalyst material for MB dye degradation.

Aggregated gold nanoparticles rich in electromagnetic field “hotspots” for surface enhanced Raman scattering

A simple method for one-step synthesis of aggregated gold nanoparticles (a-AuNPs) using single-layer carbon dots (s-CDs) as the capping agents has been proposed. The obtained a-AuNPs are mainly composed of several spherical AuNPs of 20–25 nm sized, which aggregate to form nanogaps of ∼1 nm. Furthermore, the obtained a-AuNPs produce a strong localized surface plasmon resonance (LSPR) absorption band centered at around 640 nm, which is quite close to the wavelength of the commonly used 633 nm laser in surface enhanced Raman scattering (SERS). Thus, under the irradiation of 633 nm laser, a lot of electromagnetic field “hot spots” are formed at around the nanogaps, and strong SERS activity is achieved. The obtained a-AuNPs are dropped on tin-foil wafers to fabricate SERS substrates, which show the advantages of high sensitivity, fast response, good repeatability and satisfactory stability. On the basis, a sensitive SERS sensor is developed to detect malachite green in aquaculture water, with a low detection limit of 1 × 10−9 mol/L.

Fabrication of Three-Dimensional Dendritic Ag Nanostructures: A SERS Substrate for Non-Invasive Detection.

This paper discusses the fabrication of three-dimensional dendritic Ag nanostructures, showcasing pronounced Localized Surface Plasmon Resonance (LSPR) effects. These nanostructures, employed in surface-enhanced Raman scattering (SERS), function as sensors for lactic acid in artificial sweat. The dendritic structures of the silver nanoparticles (AgNPs) create an effective SERS substrate, with additional hotspots at branch junctures enhancing LSPR. We achieve differential LSPR effects by varying the distribution and spacing of branches and the overall morphology. Adjustments to electrodeposition parameters, such as current and plating solution protective agents on an anodized aluminum oxide (AAO) base, allow for precise control over LSPR intensities. By pre-depositing AgNPs, the electron transmission paths during electrodeposition are modified, which leads to optimized dendritic morphology and enhanced LSPR effects. Parameter optimization produces elongated rods with main and secondary branches, covered with uniformly sized, densely packed, non-overlapping spherical AgNPs. This configuration enhances the LSPR effect by generating additional hotspots beyond the branch tips. Fine-tuning the electrodeposition parameters improved the AgNPs' morphology, achieving uniform particle distribution and optimal spacing. Compared to non-SERS substrates, our structure amplified the Raman signal for lactic acid detection by five orders of magnitude. This method can effectively tailor SERS substrates for specific analytes and laser-based detection.

Directional picoantenna behavior of tunnel junctions formed by an atomic-scale surface defect.

Plasmonic nanoantennas have attracted much attention lately, among other reasons because of the directionality of light emitted by fluorophores coupled to their localized surface plasmon resonances. Plasmonic picocavities, i.e., cavities with mode volumes below 1 nm3, could act as enhanced antennas due to their extreme field confinement, but the directionality on their emission is difficult to control. In this work, we show that the plasmonic picocavity formed between the tip of a scanning tunneling microscope and a metal surface with a monoatomic step shows directional emission profiles and, thus, can be considered as a realization of a picoantenna. Electromagnetic calculations demonstrate that the observed directionality arises from the reshaping and tilting of the surface charges induced at the scanning tip due to the atomic step. Our results pave the way to exploiting picoantennas as an efficient way for the far-field probing and control of light-matter interactions below the nanoscale.

Sandwich Layer-Modified Ω-Shaped Fiber-Optic LSPR Enables the Development of an Aptasensor for a Cytosensing-Photothermal Therapy Circuit.

The metastasis of cancer cells is a principal cause of morbidity and mortality in cancer. The combination of a cytosensor and photothermal therapy (PTT) cannot completely eliminate cancer cells at one time. Hence, this study aimed to design a localized surface plasmonic resonance (LSPR)-based aptasensor for a circuit of cytosensing-PTT (COCP). This was achieved by coating a novel sandwich layer of polydopamine/gold nanoparticles/polydopamine (PDA/AuNPs/PDA) around the Ω-shaped fiber-optic (Ω-FO). The short-wavelength peak of the sandwich layer with strong resonance exhibited a high refractive index sensitivity (RIS). The modification with the T-shaped aptamer endowed FO-LSPR with unique characteristics of time-dependent sensitivity enhancement behavior for a sensitive cytosensor with the lowest limit of detection (LOD) of 13 cells/mL. The long-wavelength resonance peak in the sandwich layer appears in the near-infrared region. Hence, the rate of increased localized temperature of FO-LSPR was 160 and 30-fold higher than that of the bare and PDA-coated FO, indicating strong photothermal conversion efficiency. After considering the localized temperature distribution around the FO under the flow environment, the FO-LSPR-enabled aptasensor killed 77.6% of cancer cells in simulated blood circulation after five cycles of COCP. The FO-LSPR-enabled aptasensor improved the efficiency of the cytosensor and PTT to effectively kill cancer cells, showing significant potential for application in inhibiting cancer metastasis.

Mechanisms of electrical transition using a conformal MoOx cap on Mo-doped VO2 thermochromics

Mo-doped VO2 thin-films are deposited on the soda-lime glass by a reactive high-power impulse magnetron co-sputtering technique (R-HiPIMS). Rapid thermal annealing at 500 °C for 3 min is performed to achieve the fabrication under low thermal budget. To prevent VO2 from further oxidation, a conformal and semi-conducting MoOx film is applied as the capping layer by the plasma-enhanced atomic layer deposition (PE-ALD). After MoOx film is deposited, an electrical transition in the resistance ratio of 6–10 orders of magnitude has been found, especially for MoOx thicknesses less than 20 nm. A secondary phase of V2O3 plays an important role in abrupt change of current transportation. Also, the hysteresis of optical transition in transmittance at a wavelength of 2500 nm shows that both the width and transition temperature (TC) decrease with increasing the thickness of the MoOx cap. Moreover, the effect of localized surface plasmonic resonance (LSPR) due to the Karst-like structure has been detected by the absorption spectrum. The variations in LSPR peak, such as intensity, blue-shifting, and red-shifting, originated from either excess carrier or structure change are discussed. The high aspect ratio of surface morphology is further examined by atomic force microscopy. In addition, the coverage of MoOx on Mo-doped VO2 concerning the friction behavior is evaluated by lateral force microscopy (LFM), which is helpful in clarifying the responsible mechanisms during TC transition.

Dynamically Tunable Localized Surface Plasmon Resonance in Self‐Assembled SrCoOx‐Au Vertically Aligned Nanocomposite Thin Films

AbstractWhile the physical principles for regulating localized surface plasmon resonance (LSPR) are well established, dynamically tuning the LSPR in a given material post synthesis remains challenging. Herein, this study demonstrates a strategy for dynamically tuning the LSPR of Au nanostructures by selectively altering the dielectric environment. Au is integrated with an electrochemically gatable oxide, i.e., SrCoOx (SCO), into vertically aligned nanocomposite thin films via a self‐assembly growth mechanism, where Au develops into nanopillars embedded in the SCO matrix. By selectively controlling the tri‐state phase transitions of SCO matrix via varying the bias voltage polarity in ionic liquid gating (ILG), the LSPR behavior of Au nanopillars can be dynamically tuned. Specifically, gating with a negative bias fully suppresses the LSPR, while a positive bias leads to a continuous blueshift of the LSPR wavelength upon increasing the ILG duration. This work not only opens new directions for the dynamic control of LSPR of noble metal nanostructures, but also offers insight to the voltage control of multifunctionalities via structural and physical intercoupling between different phases in self‐assembled nanocomposites.

Investigation of dependent scattering criterion for dispersed particulate medium: Effects of metal particle plasmon resonances and host medium absorption

Spectral radiative transfer between particles within dispersed particulate medium is prevalent across various fields, which may be influenced by the microscopic dependent scattering effect (DSE). However, independent scattering assumption (ISA) is only employed in the radiative transfer of most studies, which can lead to significant errors. Consequently, there is an urgent need to establish the more accurate and widely applicable dependent scattering criterion for determining whether the radiative transfer is independent or dependent scattering. However, the most existing criteria are only applicable under the assumption of optically soft particles with weak absorption. This limitation results in the criteria being valid only for certain types of particles, excluding nonmetal particles with highly complex refractive indices and metal particles with strongly absorption. Furthermore, the existing criteria also fail to consider the impact of host medium absorption (HMA) on the localized surface plasmon resonance (LSPR) of metal particles and the DSE between particles. It would represent another significant limitation. To address these above limitations, this paper develops a comprehensive and systematic dependent scattering criterion with considering the plasmon resonances for metal particle and host medium absorption. The multiple sphere T-matrix (MSTM) method, generalized Mie scattering, and Monte Carlo ray tracing (MCRT) method are further employed to calculate and compare the radiative properties across different scales. The extinction cross section is the most suitable contrast parameter in the dependent scattering criterion with the consideration of host medium absorption. Clearance-to-wavelength ratio c/λ is used to characterize dependent scattering criterion. Consequently, the dependent scattering criterion c/λ for nonmetal particles is 6. While the dependent scattering criterion c/λ for metal particles is 5.5.