Effective Energy Transfer Research Articles

Efficient tunable temperature sensitivity in thermally coupled levels of Er3+/Yb3+ co-doped BaBi2Nb2O9 ferroelectric ceramic

Er3+/Yb3+ co-doped ferroelectric ceramic BaBi2-0.04-yNb2Er0.04YbyO9 (y = 0.00, 0.02, 0.04, 0.06, 0.08, 0.10, and 0.12) are prepared by solid-state method and investigated for their structural and upconversion luminescence properties. High-resolution X-ray pattern investigation confirmed the ceramic's orthorhombic structure. Microstructure of sintered ceramic surface resembles plate-like structures and consists of non-uniform grains that are randomly oriented. Upconversion luminescence (UCL) spectra revealed two prominent green emission bands near 535 and 557 nm and a notable red band at 672 nm, corresponding to a 980 nm excitation wavelength. Decay time measurements support the effective energy transfer from Yb3+ to Er3+ ions. The average lifetime increases with increasing Er3+/Yb3+ doping concentration up to the optimal concentration (y = 0.10). Pump power dependence demonstrates that two photons are required to generate green and red UC illumination. The absolute sensitivity, Sa (0.69% K−1 and 0.58% K−1) and relative sensitivity, Sr (1.1% K−1 and 1.01% K−1) have been recorded for the first time on Er3+/Yb3+ co-doped BaBi2-0.04-yNb2Er0.04YbyO9 ceramic at y = 0.06 and 0.10, respectively, suggesting it is a viable non-contact sensor ceramic whose sensitivity can be tuned by varying dopant concentrations.

Pyrogallol Detection Based on the Cobalt Metal–Organic Framework of Nanomaterial-Enhanced Chemiluminescence

The cobalt metal–organic framework (Co-MOF) is a kind of crystalline porous material within a periodic network structure, which is formed via the self-assembly of a Co metal center and a bridged organic ligand. In this paper, a Co-MOF was facilely synthesized via an ultrasonic method and applied to enhance the chemiluminescence (CL) emission of the NaIO4-H2O2 system. The synthesized Co-MOF was nanosheet-like in nature and stacked in 2–3-micrometer flower shapes. Compared to the NaIO4-H2O2 system without a Co-MOF, the CL intensity of the Co-MOF-NaIO4-H2O2 system was enhanced about 70 times. This CL mechanism was determined to be a result of the synergistic effects of chemiluminescence resonance energy transfer (CRET) and electron–hole annihilation (EHA). The Co-MOF not only acted as a catalyst to accelerate the generation of reactive oxygen species in the CL reaction, but also worked as an emitter to further enhance the CL. Based on the Co-MOF-NaIO4-H2O2 system, a highly sensitive CL analysis method was established for pyrogallol (PG) detection. Addition of PG into the CL system generated 1O2*, which could transfer energy to the Co-MOF and further enhance the CL response. The enhanced CL was linear with the PG concentration. The CL analysis method exhibited a linear range of 1 × 10−4 M to 1 × 10−7 M, as well as having a linear correlation coefficient of 0.9995 and a limit of detection of (S/N = 3) of 34 nM.

Hydrothermal synthesis and ionic sensing properties of graphitic carbon nitride quantum dots

BackgroundThis work adopts an efficient method including thermal calcination, surface hydroxylation, and hydrothermal cutting to synthesize graphitic C3N4 quantum dots (CNQDs) for detecting metal ions in aqueous solutions. MethodsFunctionalized CNQDs, ranged from 2 to 6 nm in particle size, were of layered crystalline and contain a large amount of surface functionalities such as carbonyl, carboxylic, and amino groups. The CNQD suspension exhibited a maximal fluorescence intensity at 420 nm with high quantum yield of 13.6% under UV irradiation. Significant findingsThe CNQD suspension demonstrated superior sensitivity and selectivity toward iron ions with ppm-level detection limit in liquid phase. The Stern-Volmer analysis revealed that CNQD suspension was appropriate for the detection of Fe3+ and Fe2+ ions with LOD of 6.5 and 7.7 ppm, respectively. The fluorescence quenching mechanism of CNQD suspension mainly originates from a strong interaction between the ions and the surface functionalities followed by the photoinduced energy transfer effect, thus inducing the fluorescence extraction. Moreover, the CNQD suspension also offers a satisfactory biocompatibility toward 3T3 cell after 24 h. Accordingly, the robust design of CNQDs developed in this work paves the way for developing highly sensitive and selective probes for detecting target species in aqueous solutions.

Multi-functionalized Metallo-Supramolecular Spoked Wheels: Their Emission-Tunable Hierarchically Assembled System with Dye Molecules.

Supramolecular architectures with multiple emissive units are especially appealing due to their desired properties, such as artificial light harvesting and white-light emission. But fully achieving multi-wavelength photoluminescence in a single supramolecular architecture remains a challenge. In this paper, functionalized supramolecular architectures containing twelve metal centers and six pyrene moieties were nearly quantitatively synthesized by multi-component self-assembly and fully characterized by 1D and 2D nuclear magnetic resonance, dynamic light scattering, electrospray ionization mass spectrometry, traveling-wave ion mobility mass spectrometry, and transmission electron microscopy. Moreover, the hierarchical nano-assemblies were prepared by introducing anionic dyes to the positively charged self-assembled framework, which contained three luminescence centers, namely, pyrene, tpy-Cd coordination parts, and Sulforhodamine B anions. Such a hierarchically assembled system displayed tunable emission by taking full advantage of aggregation-induced emission enhancement, aggregation-caused quenching, and fluorescence resonance energy transfer effects and showed the diverse emission colors. This research provides a new insight for constructing multiple emissive metallo-supramolecular assemblies.

Efficient CO2 photoreduction enabled by the energy transfer pathway in metal‐organic framework

AbstractMany studies in metal‐organic frameworks (MOFs) aiming for high photocatalytic activity resort to self‐assembling both energy donor and acceptor building units in skeleton to achieve effective energy transfer, which, however, usually needs tedious synthetic procedure and design of a new MOF. In this work, we demonstrated that building a Förster resonance energy transfer (FRET) pathway can be realized through suitable molecular doping in a given MOF structure without altering the original porous structure, presenting an alternative strategy to design efficient photocatalysts for CO2 reduction. In situ electron spin resonance, ultrafast transient absorption spectroscopy, and computational studies reveal that the FRET‐induced excitation has dramatically altered the exciton transfer pathway in structure and facilitated electron‐hole separation. As a result, the molecular doped MOFs synthesized through one‐pot reaction show outstanding selectivity (96%) and activity (1314 μmol·g−1·h−1) for CO production versus almost no activity for the pristine MOFs, and this result stands out from existing competitors. Furthermore, the reaction mechanism was proposed and the intermediate signals were detected by in situ diffuse reflectance infrared Fourier transform spectroscopies. This study presents a clear picture of building FRET process in MOFs through molecular doping and provides a new design strategy for MOF‐based photocatalysts.

Activation energy and convective heat transfer effects on the radiative Williamson nanofluid flow over a radially stretching surface containing Joule heating and viscous dissipation

This article recognizes the time-dependent axisymmetric flow of a non-Newtonian Williamson fluid caused by a radially stretching surface in the presence of nanoparticles in the porous medium. The combined impacts of Joule heating and viscous dissipation on the flow profiles are also discussed. Chemical reaction at the surface is implemented. The convective heat transfer model and Brownian motion are also studied for the electrically conducting nanofluid flow. The Williamson nanofluid flow has been modeled using a set of partial differential equations based on the fundamental conservation laws of mechanics. By using nondimensional quantities, these equations are first transformed into ordinary differential equations. The Galerkin weighted residual method is performed to resolve these equations numerically. Visual displays and detailed descriptions of the impacts of relevant variables on the thermal performance, concentration field, and velocity field are provided. It is noticed that the thermal profile enhances as the values of the Brownian motion parameter and temperature ratio parameter increase while declining when the values of the velocity slip parameter increase. The Biot number, activation energy, and unsteadiness parameters have proportional effects on the concentration profile, but the reaction parameter has inversely proportional effects on the concentration profile. Heat transfer rate increases with increasing the Weissenberg number and velocity slip parameter, drops with increasing the thermophoresis and unsteadiness parameters, and the Arrhenius activation energy. Finally, a comparison of the obtained numerical solution for the porous and nonporous medium are also done graphically and discussed in details.

Photosynthesis in the Biomass Model Species Lemna minor Displays Plant-Conserved and Species-Specific Features.

Lemnaceae are small freshwater plants with extraordinary high growth rates. We aimed to test whether this correlates with a more efficient photosynthesis, the primary energy source for growth. To this end, we compared photosynthesis properties of the duckweed Lemna minor and the terrestrial model plant Arabidopsis thaliana. Chlorophyll fluorescence analyses revealed high similarity in principle photosynthesis characteristics; however, Lemna exhibited a more effective light energy transfer into photochemistry and more stable photosynthesis parameters especially under high light intensities. Western immunoblot analyses of representative photosynthesis proteins suggested potential post-translational modifications in Lemna proteins that are possibly connected to this. Phospho-threonine phosphorylation patterns of thylakoid membrane proteins displayed a few differences between the two species. However, phosphorylation-dependent processes in Lemna such as photosystem II antenna association and the recovery from high-light-induced photoinhibition were not different from responses known from terrestrial plants. We thus hypothesize that molecular differences in Lemna photosynthesis proteins are associated with yet unidentified mechanisms that improve photosynthesis and growth efficiencies. We also developed a high-magnification video imaging approach for Lemna multiplication which is useful to assess the impact of external factors on Lemna photosynthesis and growth.

The Upconversion Luminescence of Ca3Sc2Si3O12:Yb3+,Er3+ and Its Application in Thermometry.

To develop novel luminescent materials for optical temperature measurement, a series of Yb3+- and Er3+-doped Ca3Sc2Si3O12 (CSS) upconversion (UC) phosphors were synthesized by the sol-gel combustion method. The crystal structure, phase purity, and element distribution of the samples were characterized by powder X-ray diffraction and a transmission electron microscope (TEM). The detailed study of the photoluminescence emission spectra of the samples shows that the addition of Yb3+ can greatly enhance the emission of Er3+ by effective energy transfer. The prepared Yb3+ and Er3+ co-doped CSS phosphors exhibit green emission bands near 522 and 555 nm and red emission bands near 658 nm, which correspond to the 2H11/2→4I15/2, 4S3/2→4I15/2, and 4F9/2→4I15/2 transitions of Er3+, respectively. The temperature-dependent behavior of the CSS:0.2Yb3+,0.02Er3+ sample was carefully studied by the fluorescence intensity ratio (FIR) technique. The results indicate the excellent sensitivity of the sample, with a maximum absolute sensitivity of 0.67% K-1 at 500 K and a relative sensitivity of 1.34% K-1 at 300 K. We demonstrate here that the temperature measurement performance of FIR technology using the CSS:Yb3+,Er3+ phosphor is not inferior to that of infrared thermal imaging thermometers. Therefore, CSS:Yb3+,Er3+ phosphors have great potential applications in the field of optical thermometry.

Modulating Backbone Conjugation of Polymeric Thermally Activated Delayed Fluorescence Emitters for High‐Efficiency Blue OLEDs

AbstractBlue conjugated polymers‐based OLEDs with both high efficiency and low efficiency roll‐off are under big challenge. Herein, a strategy of local conjugation is proposed to construct high‐efficiency blue‐emitting conjugated polymers, in which the conjugation degree of polymeric backbones is adjusted by inserting different spacers. In this way, the energy level of triplet state and the energy transfer direction of the polymeric main‐chains can be effectively regulated. Benefiting from such fine regulation, the prepared alternative copolymers Alt‐PB36 with local conjugated main‐chains can better suppress the accumulation of long‐lived triplet excitons comparing with the complete conjugated polymers. The higher PLQY of Alt‐PB36 also verifies the effective energy transfer from the polymeric main‐chains to the TADF units. Accordingly, Alt‐PB36 based solution‐processed OLEDs achieve an EQEmax of 11.6% and a very low efficiency roll‐off of 2.8% at 100 cd m−2 and 15.2% at 500 cd m−2. This result represents the best efficiency among blue light‐emitting conjugated polymer‐based OLEDs so far under high luminance.

Facile Synthesis of Multicolored Stacked Quantum Dot Films for Efficient White Light Emission

Quantum dot (QD)-based white light-emitting diodes (LEDs) or white QD-LEDs were successfully fabricated by stacking QD films of primary colors (i.e., red, green, and blue). An ultrathin ZnO film was deposited between each QD layer to facilitate the formation of a tricolor-stacked QD structure. Such stacked QD films effectively suppress the Förster resonance energy transfer between QDs and enable efficient blue light emission, unlike randomly mixed QD films of different colors. The photoluminescence (PL) spectra of various QD films were obtained to study the change in the corresponding color gamut with applied voltage. In addition, QD-LEDs were fabricated based on the PL behavior and electronic band diagrams of QDs of different colors. Maximum luminance and peak EQE of white QD-LED shows 5700 cd/m2 and 1.1% compared to 2200 cd/m2 and 0.3% of QD-LED with mixed QD layer. Finally, a smooth color transition and white light emission were achieved using a blue/green/red stacking sequence for the QDs, which successfully suppressed the energy transfer effect. The overall performance and brightness of the white QD-LEDs synthesized in this study can be further enhanced by developing high-performance blue QDs.

Background-Quenched Aggregation-Induced Emission through Electrostatic Interactions for the Detection of Poly(ADP-ribose) Polymerase-1 Activity.

Poly(ADP-ribose) polymerase-1 (PARP1) is a potential biomarker and therapeutic target for cancers that can catalyze the poly-ADP-ribosylation of nicotinamide adenine dinucleotide (NAD+) onto the acceptor proteins to form long poly(ADP-ribose) (PAR) polymers. Through integration with aggregation-induced emission (AIE), a background-quenched strategy for the detection of PARP1 activity was designed. In the absence of PARP1, the background signal caused by the electrostatic interactions between quencher-labeled PARP1-specitic DNA and tetraphenylethene-substituted pyridinium salt (TPE-Py, a positively charged AIE fluorogen) was low due to the fluorescence resonance energy transfer effect. After poly-ADP-ribosylation, the TPE-Py fluorogens were recruited by the negatively charged PAR polymers to form larger aggregates through electrostatic interactions, thus enhancing the emission. The detection limit of this method for PARP1 detection was found to be 0.006 U with a linear range of 0.01~2 U. The strategy was used to evaluate the inhibition efficiency of inhibitors and the activity of PARP1 in breast cancer cells with satisfactory results, thus showing great potential for clinical diagnostic and therapeutic monitoring.

Two Bisligand-Coordinated Luminescent Zn(II)-Coordination Polymers for Sensing of Ions and Pesticides in Aqueous Solutions

Two coordination polymers (CPs) [Zn(PTA)(DTP)(H2O)2]•(DMF) (CP-1) and [Zn(BTC)(DTP)]•(CH3CN)1.5•(H2O)4 (CP-2) with one- and two-dimensional architectures were synthesized from Zn(II) ion and different organic linkers like terephthalic acid (H2PTA), benzene-1,3,5-tricarboxylic acid (H3BTC), and 3,5-di(1,2,4-triazol-1-yl) pyridine (DTP). The fluorescent sensing experiments showed that the two CPs displayed effective, sensitive, and selective abilities towards Fe3+ and Cr2O72-. For sensing the pesticides, CP-1 outperforms in sensing of metamitron (MMT) and CP-2 is ultrasensitive towards imidacloprid (IMI). The possible mechanisms involved in the quenching of the fluorescence intensity include the inner filter effect (IFE) and the fluorescence resonance energy transfer (FRET) effect.

Photochromic Polyurethane Coatings with Cross-Linked Structure and Self-Healing Behavior Based on the FRET Effect.

Intelligent fluorescent coatings have received widespread attention in the encryption technique field such as anti-counterfeit, while the traditional fluorescent coatings are easy to be damaged by external force. In this study, the fluorescent and self-healing anti-counterfeit coatings are prepared after rational molecular design. Two polymers containing fluorescent groups, including polyurethane containing the anthracene (AN) side group and polyimide containing the naphthalenediimide (NDI) structure are synthesized to realize multiple color changes with fluorescence through simply blending. Due to the overlapping fluorescence spectra of the groups, enabling the fluorescence resonance energy transfer effect (FRET), the coating with different group ratios exhibits tunable fluorescence under the same excitation light, providing diverse patterns. Moreover, due to the reversible photo-crosslinking and thermal de-dimerization properties of anthracene, the recording, erasure, and rewriting of the surface pattern can be realized, and the fluorescent anti-counterfeit coatings exhibit excellent self-healing properties after cross-linking due to the FRET effect, which solves the problem of poor healing and ensures the stability and integrity. The fluorescent coating with cross-linked structure and self-healing behavior based on the FRET effect greatly expands the functional applications of traditional polyurethane materials.

Synchronous Generation of Electrical and Cellular Energies via Body-Mediated Energy Transfer: Inevitable Electric Field Concentration

The effect of body-mediated energy transfer and harvesting on biological tissues has not been considered yet. We demonstrate through clinical protocols that body-mediated energy harvesting concentrates inevitable and local electric fields in biological tissues, which reduces muscle fatigue (6.4%, P-value = 0.020). The waveform (AC and DC) and intensity (∼3000 mV/mm) of these electric fields can be adjusted by controlling several variables (grounding method, external resistance, charging capacitor) depending on the purpose (usefulness, energy strength) without using any additional battery or wiring. Moreover, the harvested energy can be used to operate small electronic devices semipermanently. These findings indicate that body-mediated energy harvesting is a promising solution for powering wearable technologies and as a noninvasive treatment for harvesting energy and stimulating biological tissues synchronously.

Optical thermometry based on fluorescence intensity ratio of doped ions and matrix in CaWO4: Eu3+ phosphors

In this work, Eu3+ doped CaWO4 phosphors with various concentrations were obtained by hydrothermal method. XRD and the FE-SEM were used to indicate the structure and morphology of the samples. The temperature-dependent excitation and emission spectra of Eu3+ doped CaWO4 phosphors were measured. Analyzing the test results found that the luminescence of WO42− decreased significantly with the increase of temperature, showing a normal thermal quenching trend, but the luminescence of Eu3+ showed a novel trend of first rising and then decreasing. This novel phenomenon is the result of enhancement of energy transfer effect from the matrix to Eu3+ with temperature increase. The thermal quenching trend of Eu3+ and WO42− luminescence is markedly different. So, the high relative sensitivity is obtained by using FIR of Eu3+ and WO42− to represent temperature. The maximum of relative sensitivity was 3.25% K−1 at 303 K. Meanwhile, the luminescence color of phosphor changed significantly from blue to orange-red with increasing temperature. To sum up, Eu3+ doped CaWO4 phosphor was a potential optical temperature sensing material.

Enhanced near-infrared emission of Er3+ as a synergistic effect of energy transfers in Bi3TeBO9:Yb3+/Er3+ phosphors

Enhanced near-infrared emission at 1531 nm of Er3+ ions excited by Bi3+ and/or Yb3+ ions was revealed in Bi3TeBO9:Yb3+/Er3+ phosphors. The microcrystalline powders investigated: Bi3TeBO9:Er3+, Bi3TeBO9:Yb3+ and Bi3TeBO9:Yb3+/Er3+ were synthesized by means of the modified Pechini method. Their hexagonal structure with P63 space group was confirmed by XRD measurements. The morphology of the above-mentioned samples was analyzed using SEM technique. The results of μ-Raman investigations showed low phonon energy of Bi3TeBO9 matrix. The characteristic Er3+ emission at 1531 nm assigned to the 4I13/2 → 4I15/2 transition in Bi3TeBO9:Er3+ and Bi3TeBO9:Yb3+/Er3+ powders was excited by Bi3+ or Yb3+ ions (the 1S0 → 3P1 or 2F7/2 → 2F5/2 transitions) upon their excitation at 327 or 975 nm, respectively. It was revealed that the effective energy transfer from the excited Bi3+ ions (at 327 nm) directly to Er3+ ions or indirectly to Er3+ ions both via the excitation of Bi3+ ions in VIS range or excitation of Yb3+ ions in the NIR range results in synergistic effect, which produces enhanced emission at 1531 nm of Er3+ ions in Bi3TeBO9:Yb3+/Er3+ system. Moreover, it was found that the effective energy transfer from the excited Yb3+ ions (at 975 nm) directly to Er3+ ions results in the efficient emission at 1531 nm of Er3+ ions. Furthermore, the calculations of energy transfer efficiency and quantum efficiency proved the effective energy transfer from Bi3+ to Yb3+ and from Yb3+ to Er3+ ions. The corresponding mechanisms of energy transfer processes in the investigated materials were discussed on the basis of reflectance, excitation and emission spectra and measured decay times. The results indicate a potential of the use of Bi3TeBO9:Yb3+/Er3+ powders as spectral converters in new generation of photovoltaic devices.

Photoluminescence from Cu / Mn: ZnSe quantum dots and their phase transformation in silicate glass

To realize the polychromatic and tunable luminescence of ZnSe quantum dots (QDs) in glass, Cu and Mn co-doped ZnSe QDs (Cu/Mn: ZnSe QDs) glass were prepared by melt quenching and subsequent heat treatment method. For the ZnSe QDs glass without Cu and Mn dopants, there is only intrinsic luminescence from ZnSe QDs observed. For Cu/Mn: ZnSe QDs glass, the band edge emission from ZnSe QDs is quenched and the broadband emission from Cu2+/Mn2+ ions is observed, which is resulted by the effective energy transfer from ZnSe QDs to Cu2+/Mn2+ ions. With the increase of heating temperature, the emission spectra of Cu/Mn: ZnSe QDs glass change from green to orange light, which is characteristic luminescence wavelengths of Cu2+ and Mn2+ ions, respectively. For the ZnSe QDs glass without Cu2+ and Mn2+ dopants, ZnSe QDs undergo a phase transformation from the cubic to the hexagonal structure at higher heating temperature (≥610 °C) than those of Cu/Mn: ZnSe QDs glass at 600 °C and Cu-doped ZnSe QDs glass at 580 °C, in addition, For Cu/Mn: ZnSe QDs glass, the phase transformation temperature drops to 600 °C. For Cu-doped ZnSe QDs glass, the phase transformation temperature is further reduced to 580 °C. However, for Mn-doped ZnSe QDs glass, there is no phase transformation. It indicated that Cu2+ promotes the phase transformation of ZnSe QDs.

Position and Orientation dependent Hybridization and Energy transfer of Dipole Emitter around Plasmonic Homodimers

AbstractA dipole emitter (analogous to organic molecules) placed near any dielectric or metal nanoparticles, based on their spatially constrained location and orientation, vividly emulate optical nanoantennas. Herein, we have extensively simulated the single dipole emitter interaction with spherical homodimers of noble metal gold and silver nanoparticles for different positional dependent orientations, exemplifying systematically the hybridization (Rabi splitting), quenching and diffuse non‐radiative energy transfer effects. The blue‐shifted scattering spectra of the coupled dipole emitter with individual Ag and Au homodimers quantify and corroborate the corresponding quantum yield/efficiency estimations. Such spatially oriented emitter interaction further distinctly reveals the enhanced near‐field and far‐field effects of the plasmonic dimer system in terms of dipolar and quadrupolar resonances, arising due to the induced polarization by respective incident electric and opto‐magnetic field components. Understanding the surface‐enhanced behavior of organic molecules that are either incorporated or randomly attached (experimentally) on the surface of metal nanoparticles will benefit greatly from the present comprehensive data analysis.

A sensitive fluorescence nanoplatform for monitoring benzoyl peroxide in food using carbon dots coupled with glutathione capped gold nanoparticles as FRET probe.

Herein, a sensitive fluorescence nanoplatform for benzoyl peroxide (BPO) detection is constructed from carbon dots (CDs) and glutathione capped gold nanoparticles (GSH-AuNPs). The fluorescence of CDs is first quenched due to the fluorescence resonance energy transfer (FRET) effect in the presence of GSH-AuNPs, and then effectively recovered when adding BPO. The detection mechanism lies in the aggregation of AuNPs in a high salt background due to oxidation of GSH caused by BPO, thus the amount of BPO is reflected by the variations of the recovered signals. The linear range and detection limit in this detection system is found to be 0.05-200μM (R2=0.994) and 0.1µgg-1 (3σ/K), respectively. Several possible interferents with high concentration show little influence on BPO detection. The proposed assay exhibits good performance for BPO determination in wheat flour and noodles, demonstrating its applicability for facile monitoring BPO additive amount in real foods.

Electromagnetic deactivation spectroscopy of human coronavirus 229E

An investigation of the deactivation of pathogens using electromagnetic waves in the microwave region of the spectrum is achieved using custom-built waveguide structures. The waveguides feature sub-wavelength gratings to allow the integration of an air cooling system without disturbing the internal propagating fields. The waveguides are tapered to accommodate an experimental sample internally with sufficient surrounding airflow. The proposed methodology allows for precise control over power densities due to the well-defined fundamental mode excited in each waveguide, in addition to temperature control of the sample due to microwave exposure over time. Human coronavirus (HCoV-229E) is investigated over the 0–40 GHz range, where a peak 3-log viral reduction is observed in the 15.0–19.5 GHz sub-band. We conclude HCoV-229E has an intrinsic resonance in this range, where nonthermal structure damage is optimal through the structure-resonant energy transfer effect.