Electronic Spectra Research Articles

Bismuth as a Z-Type Ligand: an Unsupported Pt-Bi Donor-Acceptor Interaction and its Umpolung by Reaction with H2.

Establishing unprecedented types of bonding interactions is one of the fundamental challenges in synthetic chemistry, paving the way to new (electronic) structures, physicochemical properties, and reactivity. In this context, unsupported element-element interactions are particularly noteworthy since they offer pristine scientific information about the newly identified structural motif. Here we report the synthesis, isolation, and full characterization of the heterobimetallic Bi/Pt compound [Pt(PCy3)2(BiMe2)(SbF6)] (1), bearing the first unsupported transitionmetal→bismuth donor/acceptor interaction as its key structural motif. 1 is surprisingly robust, its electronic spectra are interpreted in a fully relativistic approach, and it reveals an unprecedented reactivity towards H2.

Ab initio investigation of the geometrical behavior in solution and electronic structure of the anion complexes [bis(1,3-dithiole-2-thione-4,5-dithiolate)M], for M = Bi(III), Sb(III), and Zn(II).

1,3-Dithiole-2-thione-4,5-dithiolate (dmit) ligands are known for their conductive and optical properties. Dmit compounds have been assessed for use in sensor devices, information storage, spintronics, and optical material applications. Associations with various metallic centers endow dmit complexes with magnetic, optical, conductive, and antioxidant properties. Optical doping can facilitate the fabrication of magnetic conductor materials from ground-state nonmagnetic cations. While most studied complexes involve transition-metal centers due to their diverse chemistry, compounds with representative elements are less explored in the literature. This study investigated the structural and electronic properties of bisdmit complexes with representative Bi(III), Sb(III), and Zn(II) cations. AIMD calculations revealed two new geometries for Bi(III) and Zn(II) complexes, diverging from the isolated geometry typically used in quantum chemical calculations. The coordination of acetonitrile molecules to the cationic centers of the complexes resulted in unstable structures, while the dimerization of the complexes was stable. SA-CASSCF/NEVPT2 calculations were applied to the structures of the isolated complexes and stable dimers, confirming the multireference character of the electronic structure of the three systems and the multiconfigurational character of the Bi(III) complex. The electronic spectra simulated by the STEOM-DLPNO-CCSD calculations accurately reproduced the experimental UV‒Vis spectra indicating the participation of the isolated Bi(III) dmit complex and its dimeric form in solution. AIMD calculations of the dmit salts were conducted using the GFN2-xTB method with 60 explicit acetonitrile molecules as the solvent at 300K for a total simulation time of 50.0ps, with printing intervals of 0.5fs. The final geometries were optimized employing the PBEh-3c compound method, incorporating implicit conductor-like polarizable continuum model (CPCM) solvation for acetonitrile. Local energy decomposition (LED) analysis at the DLPNO-CCSD(T)/Def2-TZVP level of theory was utilized to investigate the stability of the complex geometries identified by AIMD. The electronic structures of the complexes were assessed using the SA-CASSCF/NEVPT2/Def2-TZVP method to confirm the multiconfigurational and multireference nature of their electronic structures. Electronic spectra were analyzed using the STEOM-DLPNO-CCSD/Def2-TZVP method, with CPCM used to simulate an acetonitrile medium.

The band structure of a chain of periodically ordered different quantum dots

The paper introduces a model for a superlattice comprising periodically arranged quantum dots (QDs) and proposes a method for calculating the energy spectrum. This theory was applied to a chain of QDs. The study employed the effective mass approximation and solved the Schrödinger equation using the tight-binding model and nearest neighbor approximation. The energy spectra of electrons were determined as functions of the wave vector, and the theory facilitated the calculation of dispersion dependencies and bandwidths. The presence of different QDs resulted in the subdivision of the mini-zone into upper and lower zones. It was demonstrated and analyzed that the width of the upper zones consistently exceeds that of the lower ones. Furthermore, when the QDs possess identical sizes and materials, no forbidden zone is observed.

Characterization of Copper nanoparticles obtained in AOT reverse micelles using flavonoids as a reducing agent

Purpose of the study. To characterize copper nanoparticles obtained in reverse micelles of sodium bis-(2-ethylhexyl)-sulfosuccinate (AOT) using flavonoids: quercetin and rutin in comparison with traditional reducing agents - sodium borohydride and hydrazine. Methods. Chemical synthesis of copper nanoparticles, spectrophotometry to determine the maximum of the plasmon absorption band of copper nanoparticles, electron transmission microscopy. Results. The reduction of copper ions using flavonoids – quercetin and rutin – confirmed the possibility of obtaining copper nanoparticles in the Cu+2/AOT/isooctane system (AOT is sodium bis-(2-ethylhexyl)-sulfosuccinate, an anionic surfactant that forms the micelle shell). During the formation of nanoparticles, “plasmonic” absorption bands were observed in the electronic spectra in the region of 400-440 nm. In the case of the traditional reducing agent, sodium borohydride, absorption is observed in the region of (439 ± 3) nm, which can also be attributed to the “plasmonic band” of copper nanoparticles, but its intensity is very low, which indicates the formation of a small amount of copper nanoparticles. Using transmission electron microscopy. The average size of copper nanoparticles was determined: 7.1, 8.2 and 18.5 nm in the case of quercetin, rutin and hydrazine, respectively. From the histograms constructed from the results of electron transmission microscopy, it follows that the use of flavonoids as reducing agents makes it possible to reduce the average size of copper nanoparticles and narrow their size distribution. Conclusion. Copper nanoparticles obtained in a reverse micellar solution of AOT in iso-octane using the flavonoids quercetin and rutin as a reducing agent have an average size of 7-8 nm and a narrower size distribution compared to reduction with hydrazine.

Pyrobacteriopheophorbide-a derivatives possessing various hydrophilic esterifying groups at the C17-propionate residues for photodynamic therapy.

Aiming at the application to photodynamic therapy, natural bacteriochlorophyll-a was converted to chemically stable free-base derivatives possessing different kinds of hydrophilic C17-propionate residues. These semi-synthetic bacteriochlorins were found to have self-assembling ability in an aqueous environment and formed stable J-type aggregates in a cell culture medium containing 0.2% DMSO. The electronic absorption spectra of all the sensitizers showed Qy absorption maxima at 754 nm in DMSO as their monomeric states, while a drastic shift of the red-most bands to ca. 880 nm was observed in the aqueous medium. The circular dichroism spectra in the medium showed much intense signals compared to those measured in DMSO, supporting the formation of well-ordered supramolecular structures. By introducing hydrophilic side chains, the bacteriochlorin sensitizers could be dispersed in the aqueous medium as their J-aggregates without the use of any surfactants. Cellular uptake efficiencies as well as photodynamic activities were evaluated using human cervical adenocarcinoma HeLa cells. Among the 11 photosensitizers investigated, the best result was obtained for a charged derivative possessing trimethylammonium terminal (17-CH2CH2COOCH2CH2N+(CH3)3I-) and photocytotoxicity of EC50 = 0.09 μM was achieved by far-red light illumination of 35 J/cm2 from an LED panel (730 nm).

Quantum Computational and Spectroscopic Investigation of 3-aminosalicylic Acid.

Quantum chemical calculations of3-aminosalicylic acid (3ASA) (monomer and dimer forms) have been performed using DFT and TD-DFT theories with B3LYP/6-311 G(d,p) functional level in the ground and excited states. Using TD-DFT with IEF-PCM model, the electronic spectra of 3ASA in solvents were computed and correlated with the experimental data. The theoretically calculated absorption and emission maxima of 3ASA (monomer) are observed in the range of 343- 347nm (S0 → S1 transition) and 429- 448nm (S1 → S0 transition), respectively. The natural bond orbital (NBO) analysis shows that charge transfer interaction contributes significantly to stabilize the molecular system. In the case of dimer, hydrogen bonding plays a dominant role in stabilizing the molecular framework. Additionally, the obtained nonlinear optical (NLO) properties: polarizability (13.86 × 10-24 e.s.u for monomer and 29.46 × 10-24 e.s.u. for dimer), first-order hyperpolarizability (4.21 × 10-30 e.s.u for monomer and 0.18 × 10-30 e.s.u for dimer) and second-order hyperpolarizability (7.44 × 10-36 e.s.u. for monomer and 14.32 × 10-36 e.s.u. for dimer) were found to be larger than those of standard organic compounds suggesting that 3ASA has a significant NLO character for optoelectronic applications. The NLO properties of dimer may differ from monomer due to dimerization. Further, the radiative lifetime, light harvesting efficiency and band gap energy were calculated, and proposed that 3ASA may be useful in photovoltaics and wide bandgap power devices. HIGHLIGHTS: • DFT and TD-DFT theories were employed to calculate structural and molecular properties of 3ASA (monomer and dimer) in ground and excited states. • HOMO-LUMO study shows monomer and dimer of 3ASA are good reactive. • NBO analysis reflects that charge transfer interactions stabilized the 3ASA molecule. • Electronic absorption/emission spectra in solvents calculated by IEF-PCM/TD-DFT method correlate with experimental results. • Calculated NLO parameters suggested that 3ASA is a potential candidate for NLO material.

Thermoelectric performance of newly discovered LiHfPdZ (Z= Al, Ga, and In) quaternary Heusler compounds: A DFT study

Li-based quaternary Heusler LiHfPdZ (Z = Al, Ga, and In) compounds have been investigated for their electronic properties, structural stability, phonon spectra, and thermoelectric performance. Band structure calculations based on Density Functional Theory, show the indirect semiconductor nature of LiHfPdZ (Z = Al, Ga, and In) compounds with band gaps of 0.73 eV, 0.79 eV, and 0.58 eV, respectively. We obtained flat Hf-5d bands (without dispersion) in the vicinity of Fermi energy (EF), resulting in a high value of Seebeck coefficient. The positive values of frequencies in the phonon dispersion curve confirm the dynamic stability of these compounds. The computed elastic properties suggested that the studied compounds are mechanically stable. The calculated values of melting points of this compounds are around 1500 ± 300 K, which ensures the stability of these compounds at high temperatures. We obtained a maximum value of the figure of merit 0.72, 0.68 and 0.67 for LiHfPdAl, LiHfPdGa and LiHfPdIn compounds respectively, which is higher than other Li based QH compounds of same kind i.e. LiHfCoSn (0.59) and LiHfCoGe (0.61) obtained by Singh et al. at same temperature. Overall, a comparatively high and stable value of ZT above 600 K is obtained only in LiHfPdAl, which suggests that it is the most suitable candidate as TE material for high-temperature applications.

Recent Development and Advancement in Quantum Dots in Pharmaceutical and Biomedical Fields for the Delivery of Drugs

Abstract: Nanoscale semiconductors known as quantum dots (QDs) are essential for drug testing because they bridge the gap between nanotechnology and the testing of drugs. QDs are a valuable tool in theranostics and treatment because of their unique physicochemical features. Due to their photoluminescence and electronic properties, including broad and continuous absorption spectra, narrow emission spectra from visible to near-infrared wavelengths, and long-lasting and high brightness, they are suitable probe materials for use in (bio)sensing (immunological) platforms. Several studies use QDs due to their optical, magnetic, electrical, photochemical, and biological features that allow them to be employed in various scientific domains. When utilized in drug delivery systems, fluorescent markers, such as QDs, can track the metabolism of drugs in the human body. Many medicinal applications, such as disease diagnosis and medication research, can benefit from these fluorescent tests. In this review article, the application of QD in drug delivery and immunoassay sensing has been described in detail.

Modelling Gd-diamond and Gd-SiC neutron detectors

A custom Monte Carlo (MC) computer model was developed to simulate thermal neutron absorption in, and subsequent photon and electron emission from, natural Gd with a view to using the material as a neutron conversion layer for neutron detectors. The MC code also modelled photon and electron detection with two dissimilar detectors: a thick (500 μm) single crystal diamond detector; and a thin (5.15 μm) commercial off the shelf (COTS) 4H-SiC photodiode detector. The detectors’ quantum detection efficiencies (QE) for hard X-rays and γ-rays were relatively low in comparison to their QE for electrons, thus making it possible to collect electron spectra from the Gd layer neutron conversion products which were not overwhelmed by photon emissions the Gd. The MC code was utilised to determine the optimal thickness of Gd for the efficient detection of a thermal neutron flux. These radiation hard and spectroscopic detectors paired with natural Gd could find utility as robust and compact thermal neutron detectors for nuclear science and engineering, space science, and other applications.

Fabrication, structural elucidation, and DFT calculation of some new hydrophilic metal chelates based on N N′‐(1‐methyl‐2‐oxoindolin‐3‐ylidene)benzohydrazide ligand: Pharmaceutical studies and molecular docking approach

Some novel FeIII, CuII, and PdII chelates incorporating N′‐(1‐methyl‐2‐oxoindolin‐3‐ylidene)benzohydrazide (MIBA) were fabricated. The tested compounds were investigated using thermogravimetric analysis (TGA), CHN, spectra analysis (IR, mass spectra, and NMR), melting point, magnetic moments, molar conductance, ultraviolet–visible spectroscopy, powder X‐ray diffraction, and computational studies. The conductance results showed that the tested FeIII, CuII, and PdII chelates are electrolytes. Magnetic and electronic spectra are applied to deduce the coordinating ability of the tested ligand, and the geometric structure of the studied chelates is found to be octahedral, distorted octahedral, and square planar for FeIII, CuII, and PdII chelates, respectively. The TGA study of these studied complexes displays that the hydrated H2O molecules, acetate, and nitrate are removed in the first and second degradation steps followed directly by degradation of the studied ligand leaving metal oxide as residue. The thermodynamic factors, like ΔS*, ΔH*, E*, A, and ΔG* are evaluated from the TGA curves and explained. The density functional theory (DFT)/B3LYP computation method was applied for the estimation of the molecular electrostatic potential (MEP; highest occupied molecular orbital [HOMO] and lowest unoccupied molecular orbital [LUMO]) energy for the studied compounds. In an in vitro study, the antimicrobial effects of the prepared compounds were screened on various strains of bacteria and fungi. It was found that tested compounds exposed a good biological efficacy through IC50 results close to reference drugs and antitumor potential against (MCF‐7, Hep‐G2, and HC‐T116) cell lines. The data obtained displayed that the studied chelates showed promising antitumor activity. The studied metal chelates were screened for in vitro antioxidant efficacy using DPPH assay. The studied compounds explained dynamic satisfying performance. Also, the crystal structures of breast cancer protein (PDB ID: 3HB5) and Escherichia coli (PDB ID: 2VF5) were performed by molecular docking simulation. Data of docking simulation suggestions are which tested compounds have biological behavior as well as have obvious benefit in the pharmaceutical business.

Synthesis, characterization, and structural analysis of hetero Ni(II)–Na(I) and Homo Ni(II)–Ni(II) dinuclear complexes with a flexible tridendate schiff base ligand

Two different novel [Ni(II)–Na(I)]n and Ni(II)–Ni(II)] complexes have been synthesized successfully using a flexible tridentate Schiff base ligand. These complexes are characterized by IR and single crystal X–ray analysis and the optical properties of these complexes have been studied by UV spectroscopy (solution and solid). The [Ni(II)–Na(I)]n complexes are repeatedly connected with another Ni(II)–Na(I) unit to yield a linear polymeric chain. The Ni(II)–Ni(II) complex shows the nature of supramolecular dimeric cluster. These results are evidenced by x-ray structural analysis. Both as-obtained complexes are shown in different structures, such as hetro metal [Ni(II)–Na(I)]n] and homo metal [Ni(II)–Ni(II)]coordination environments with the same ligand. The first one forms a linear polymeric structure whereas the second one forms a cluster. The more intense band at 2104 cm1 is assigned to the NCS ligand of compound 1. A sharp band at 1068 cm1 together with a band at 625 cm1 in compound 2 is assigned to the ClO4 stretching vibrations and these bands are evidence for the presence of ionic perchlorate (non–coordinated). The electronic spectra of compounds 1 and 2 are recorded in ACN solvent to exhibit a broad peak around 380 nm due to d-d transition.

N···C═O n → π* Interaction: Gas-Phase Electronic and Vibrational Spectroscopy Combined with Quantum Chemistry Calculations.

Herein, we have used gas-phase electronic and vibrational spectroscopic techniques for the first time to study the N···C═O n → π* interaction in ethyl 2-(2-(dimethylamino) phenyl) acetate (NMe2-Ph-EA). We have measured the electronic spectra of NMe2-Ph-EA in the mass channels of its two distinct fragments of m/z = 15 and 192 using a resonant two-photon ionization technique as there was extensive photofragmentation of NMe2-Ph-EA. Identical electronic spectra obtained in the mass channels of both fragments confirm the dissociation of NMe2-Ph-EA in the ionic state, and hence, the electronic spectrum of the fragment represents that of NMe2-Ph-EA only. UV-UV hole-burning spectroscopy proved the presence of a single conformer of NMe2-Ph-EA in the experiment. Detailed quantum chemistry calculations reveal the existence of a N···C═O n → π* interaction in all six low-energy conformers of NMe2-Ph-EA. A comparison of the IR spectrum of NMe2-Ph-EA acquired from the gas-phase experiment with those obtained from theoretical calculations indicates that the experimentally observed conformer has a N···C═O n → π* interaction. The present finding might be further valuable in drug design and their recognition based on the N···C═O n → π* interaction.

EDOT substitution site effect on fluorenone acceptor units: electrochemical polymerization and electrochromic properties of D-A systems

A series of donor-acceptor-donor type molecules (P(2,7-DEF) and P(3,6-DEF)) based on fluorenone acceptor units and 3,4-ethylenedioxythiophene (EDOT) donor units were successfully obtained by Stille coupling reaction in this work, and then generated their corresponding D-A polymers by electrodeposition method. As prepared P(2,7-DEF) and P(3,6-DEF) were characterized by CV, UV–vis spectroscopy, SEM, spectroelectrochemistry, and kinetic studies. Both of these two monomers revealed bright red/yellow light-emitting property in dilute solution. Since the π-conjugation length is longer, the oxidation potential of 2,7-DEF was reduced to 0.85 V, accompanied with red-shifted electronic spectra and emission spectra. The resulting P(2,7-DEF) demonstrated distinct electrochromic properties under various potentials with two different colors from dark-brown to blue-purple. Due to its more porous structure, P(2,7-DEF) also showed favorable optical contrast (26.3 %), very fast switching time (0.32 s), and decent coloration efficiency (221.25 cm2 C−1). However, P(3,6-DEF) displayed much worse electrochromic performances due to its bad electroactivity. P(2,7-DEF) also displayed better redox stability (remaining 79 % electroactivity after 1000 cycles), good optical stability (6 % reduction in optical contrast after 3200 s), and stable optical memory. From these results, P(2,7-DEF) can be further used as a promising near-infrared electrochromic materials.

Analytical study of some azo dyes and its medical applications

A new pharmaceutical-derived azo dye was prepared from salbutamol as an aromatic phenolic compound with sulfonamide, sulfadiazine and sulfathiazole, respectively. Dye characterization was described by Mass. , H1-NMR, I.R. and visible spectroscopy techniques. The electronic spectra of this azo dye have been studied in terms of proton harvesting and ionization. The other study was the effect of solvents with different polarities on the electronic spectra. The dye has many applications, such as its use as an indicator of a strong acid with a strong base and the use of the dye as an antibiotic. Some applications measured the biological activity of the prepared dyes against Escherichia Coli and Staphylococcus Aureus, and showed positive results.

Synthesis, characterization and analytical study of new azo ligand driven from benzocaine and its metal complexes

The synthesis and spectrum of of a new azo ligand derived from acetylacetone and benzocaine (Ethyl p-aminobenzoate)). Spectral investigations such as 1H NMR,FT.IR, 13C-NMR and Mass spectra were performed to investigate the azo dye ligand's structure. Several physiochemical approaches, FT-IR, electronic spectra, molar conductivity, atom absorption, and magnetic susceptibility were used to identify new complexes with CO(II), and Zn(II) ions Complexes that are all 1:2 [M:L] were formed using the procedures described, and an tetrahedral geometry with sp3 hybridization. At several pH ranges (2–12), the electronic spectra of these azo dyes have been examined in terms of their acid–base properties, which included determining their isosbestic points and protonation and ionization constants. In the other study, azodye were used as an inductor for acid-base titration.

Mesomorphic and optical properties of azo-ester liquid crystalline reactive mesogens with enhanced thermal stability

A series of azo-ester-linked polymerizable liquid crystalline compounds M1-M3, containing lateral methyl substitution and different terminal alkoxy substituents, e.g., −OCH3, −OCH2CH3, and −OCH2CH2CH3 have successfully been synthesized and characterized. The chemical structures of the prepared compounds were confirmed by different spectroscopic techniques. Thermogravimetric analysis revealed that all the compounds exhibited excellent thermal stability and showed two-staged decomposition patterns. The optical microscopic study revealed that all compounds displayed only the nematic phase and lateral substituent played a crucial role in the formation of single mesophase. The broad X-ray scattering peaks for M1, M2, and M3 in the 2.5–5.5 nm−1 region was observed at temperatures of 154 °C, 85 °C, and 129 °C, respectively, upon cooling from the isotropic liquid, confirming the existence of nematic mesophase. The electronic spectra of M1-M3 showed two main absorption bands with λmax ranges of 263–266 and 369–377 nm. The E-Z photoisomerization study of M1-M3 showcased that the processes followed the first-order kinetic, and the isomerization rate decreased as the alkoxy chain length increased. On the contrary, the Z-E thermal isomerization rates for M1-M3 showed insignificant changes as the alkoxy chain length increased.

Plasmon Excitation in the Interaction of Slow Singly Charged Argon Ions with Magnesium

We report angle-resolved energy spectra of electron emitted in the interaction of slow singly charged heavy ions with Mg surface. The work is focused mainly on the excitation of plasmons of Mg under Argon impact. Potential excitation of plasmons occurs when incoming ions are neutralized at the expense of the potential energy carried by incoming ions. The process competes with the known mechanisms of neutralization via Auger transitions. Differently from Al samples, our results show that the neutralization of Ar+ ions at Mg is dominated by the excitation of surface plasmons by the potential energy released in the electron capture process that neutralizes incoming ions. Bulk plasmon excitation is observed at higher impact energy and is ascribed to fast electrons excited by the transfer of the kinetic energy of incoming particles. The data show that bulk plasmon excitation occur inside the bulk, while the theoretically predicted excitation by potential energy transfer of incoming projectiles is not observed.

A thermionic electron gun to characterize silicon drift detectors with electrons

The TRISTAN detector is a new detector for electron spectroscopy at the Karlsruhe Tritium Neutrino (KATRIN) experiment. The semiconductor detector utilizes the silicon drift detector technology and will enable the precise measurement of the entire tritium β-decay electron spectrum. Thus, a significant fraction of the parameter space of potential neutrino mass eigenstates in the keV-mass regime can be probed. We developed a custom electron gun based on the effect of thermionic emission to characterize the TRISTAN detector modules with mono-energetic electrons before installation into the KATRIN beamline. The electron gun provides an electron beam with up to 25 keV kinetic energy and an electron rate in the order of 105 electrons per second. This manuscript gives an overview of the design and commissioning of the electron gun. In addition, we will shortly discuss a first measurement with the electron gun to characterize the electron response of the TRISTAN detector.

Electron acceleration in the electron dissipation region of asymmetrical magnetic reconnection driven by ultra-intensity lasers

We performed 3D Particle-In-Cell simulations to study electron acceleration in the electron dissipation region of asymmetrical electron magnetic reconnection driven by ultra-intensity lasers, which is similar to the Earth’s magnetosphere reconnection process. Within the electron dissipation region, electrons exhibit a nonthermal distribution, and as the asymmetry increases, the power-law spectrum becomes steeper. Remarkably, the electron spectrum closely resembles a delta distribution, arising from the intense acceleration imparted by the reconnection electric field near the X-line. Both parallel electric field acceleration and the Betatron acceleration mechanism play pivotal roles in this reconnection process. Furthermore, as the magnetic reconnection asymmetry intensifies, the parallel electric acceleration mechanism becomes stronger near the X-point region, whereas the Betatron acceleration mechanism wanes, primarily concentrated in the outflow region.

Ultrafast Heating-Induced Suppression of d-Band Dominance in the Electronic Excitation Spectrum of Cuprum.

The combination of isochoric heating of solids by free-electron lasers (FELs) and in situ diagnostics by X-ray Thomson scattering (XRTS) allows for measurements of material properties at warm dense matter (WDM) conditions relevant for astrophysics, inertial confinement fusion, and materials science. In the case of metals, the FEL beam pumps energy directly into electrons with the lattice structure of ions being nearly unaffected. This leads to a unique transient state that gives rise to a set of interesting physical effects, which can serve as a reliable testing platform for WDM theories. In this work, we present extensive linear-response time-dependent density functional theory (TDDFT) results for the electronic dynamic structure factor of isochorically heated copper with a face-centered cubic lattice. At ambient conditions, the plasmon is heavily damped due to the presence of d-band excitations, and its position is independent of the wavenumber. In contrast, the plasmon feature starts to dominate the excitation spectrum and has a Bohm-Gross-type plasmon dispersion for temperatures T ≥ 4 eV, where the quasi-free electrons in the interstitial region are in the WDM regime. In addition, we analyze the thermal changes in the d-band excitations and outline the possibility to use future XRTS measurements of isochorically heated copper as a controlled testbed for WDM theories.