We present a molecular study combining Raman, infrared, and UV-visible absorption spectroscopy with density functional theory (DFT) calculations to investigate triphenylene and its iodinated derivative, 1,5,9-triiodotriphe-nylene. The results provide a detailed comparison of their vibrational and electronic properties, revealing how iodine substitution affects molecular geometry and electronic structure. Iodination induces nonplanarity in the molecular backbone, leading to shifts in vibrational frequencies as well as modifications of pi-pi* transitions in the UV-visible spectra. Complementary analyses of natural bond orbitals, polarizabilities, and Hirshfeld surfaces further elucidate electronic delocalization and intermolecular interactions. These findings could enable the rational design of triphenylene-based precursors optimized for on-surface reactions, facilitating controlled formation of nanocarbon architectures with tailored structural and electronic properties.

We present detailed findings on the imaging, structure, and vibrational properties of novel hybrids of the red-emitting octahedral cluster-based compound Cs2Mo6Br14 encapsulated within single-walled carbon nanotubes (SWCNTs) of varying diameter. We explore the subtle relationship between the SWCNT internal diameter and Cs2Mo6Br14 cluster packing and find a hierarchical relationship between the nature of the cluster packing and a progressive tendency toward formation of one-dimensional (1D) structures as the SWCNT diameter narrows from 24 to 11 Å. As the internal SWCNT van der Waals radius approaches the outside diameter (OD) of the [{Mo6IIBr8i}Br6a]2- (more simplistically, [Mo6IIIBr14]2-) molecular anion species, SWCNT steric confinement causes a compositional elimination and polymerization resulting in the formation of reduced extended [Mo2IIIBr6]x nanoribbons which approximate 1D Ising model structures. Our experimental results, obtained through high-resolution transmission electron microscopy and Raman spectroscopy, are supplemented by density functional theory (DFT) calculations.

X-ray powder diffraction and multi-wavelength Raman spectroscopy were employed to characterize carbonaceous geomaterials, offering the first nanostructural analysis of rare pyrobitumen (LP) samples from the Lopérec gold deposit in Brittany, France, by comparing them to Karelian shungite (KS) and carbon allotropes samples. The inter-reticular distances d(002) for LP/KS, derived from X-ray diffraction patterns, are 3.57(1)/3.48(1) Å, with crystal thickness Lc(002) and graphitization degree of 1.4/2.0 nm and 6.9/13.1, respectively. Raman band deconvolution indicates graphitic domain sizes of La = 6.7/8.2 nm and graphene-like flake tortuosity Lt = 9.2/11.3 nm. Extensive density functional theory calculations on various 2D nanoflakes accurately predict that the D and G Raman bands may originate from graphene quantum dots, which form part of the nanostructure of these geomaterials. LP exhibits greater structural disorder than KS, along with a lower density (1.60 vs. 1.85 g/cm³), suggesting a lower degree of graphitization, likely due to formation at a lower temperature (∼300 °C). The Lopérec pyrobitumen is believed to result from a redox process involving a CO2-rich, oxidizing hydrothermal solution interacting with a local hydrocarbon source.

We present generalized information on the new type of universal quantum detectors operating on the basis of Yanson point contacts. The properties and capabilities of quantum point-contact detectors are totally different from those of conventional sensors based on the principle of changing electric conductance. To give an idea of the nature of these differences, we examine the spectral properties of Yanson point contacts, which are fundamental for understanding the operation mechanisms of quantum point-contact sensors. One of the most important features that determine the functioning of point-contact sensing elements is the quantum detection mechanisms discovered during the study of the point-contact gas-sensitive effect. The detection mechanisms based on the energy principles of analysis and conductance quantization are considered. The innovative methods developed using breath analysis with quantum point-contact sensors made it possible for the first time to detect in real time carcinogenic strains of the bacterium Helicobacter pylori and the hormonal background of the human body. The future work will be focused on universalizing the technology of quantum point-contact sensors, addressing various problems including evaluation of the general state of the human body and solutions to global ecological problems.

In this paper, we consider new quantum mechanisms for selective detection in complex gaseous media which provide the highest possible efficiency of quantum sensors and for the first time analyze their nature. On the basis of these quantum mechanisms, the concepts of quantum detection and innovative methods of analysis are developed, which are virtually impossible to implement in the conventional conductive sensors and nanosensors. Examples of original solutions to problems in the field of detection and analysis of human breath using point-contact sensors are considered. A new method of analysis based on detection of metastable quantum states of the "point-contact sensor—breath" system in dynamic mode is proposed. The conductance histogram of dendritic Yanson point contacts recorded for this system is a unique energy signature of breath which allows differentiation between the states of human body. We demonstrate that nanosized Yanson point contacts, which, thanks to their quantum properties, can replace a massive spectrometer, open up wide opportunities for solving complex problems in the field of breath analysis using a new generation of portable high-tech quantum sensor devices.

Studying the optical performance of carbon nanotubes (CNTs) filled with guest materials can reveal the fundamental photochemical nature of ultrathin one-dimensional (1D) nanosystems, which are attractive for applications including photocatalysis. Here, we report comprehensive spectroscopic studies of how infiltrated HgTe nanowires (NWs) alter the optical properties of small-diameter (dt < 1 nm) single-walled carbon nanotubes (SWCNTs) in different environments: isolated in solution, suspended in a gelatin matrix, and heavily bundled in network-like thin films. Temperature-dependent Raman and photoluminescence measurements revealed that the HgTe NW filling can alter the stiffness of SWCNTs and therefore modify their vibrational and optical modes. Results from optical absorption and X-ray photoelectron spectroscopy demonstrated that the semiconducting HgTe NWs did not provide substantial charge transfer to or from the SWCNTs. Transient absorption spectroscopy further highlighted that the filling-induced nanotube distortion can alter the temporal evolution of excitons and their transient spectra. In contrast to previous studies on functionalized CNTs, where electronic or chemical doping often drove changes to the optical spectra, we highlight structural distortion as playing an important role.

Quantum structures are ideal objects by which to discover and study new sensor mechanisms and implement advanced approaches in sensor analysis to develop innovative sensor devices. Among them, one of the most interesting representatives is the Yanson point contact. It allows the implementation of a simple technological chain to activate the quantum mechanisms of selective detection in gaseous and liquid media. In this work, a portable device for multipurpose research on dendritic Yanson point contacts and quantum sensing was developed and manufactured. The device allows one to create dendritic Yanson point contacts and study their quantum properties, which are clearly manifested in the process of the electrochemical cyclic switchover effect. The device tests demonstrated that it was possible to gather data on the compositions and characteristics of the synthesized substances, and on the electrochemical processes that influence the production of dendritic Yanson point contacts, as well as on the electrophysical processes that provide information on the quantum nature of the electrical conductance of dendritic Yanson point contacts. The small size of the device makes it simple to integrate into a micro-Raman spectrometer setup. The developed device may be used as a prototype for designing a quantum sensor that will serve as the foundation for cutting-edge sensor technologies, as well as be applied to research into atomic-scale junctions, single-atom transistors, and any relative subjects.

Abstract In this paper, we consider new quantum mechanisms for selective detection in complex gaseous media which provide the highest possible efficiency of quantum sensors. On the basis of these quantum mechanisms, the concepts of quantum detection and innovative methods of analysis are developed, which are virtually impossible to implement in the conventional conductive sensors and nanosensors. Examples of original solutions to problems in the field of detection and analysis of human breath using point-contact sensors are considered. A new method of analysis based on detection of metastable quantum states of the "point-contact sensor – breath" system in dynamic mode is proposed. The conductance histogram of dendritic Yanson point contacts recorded for this system is a unique energy signature of breath which allows differentiation between the states of human body. We demonstrate that nanosized Yanson point contacts, which, thanks to their quantum properties, can replace a massive spectrometer, open up wide opportunities for solving complex problems in the field of breath analysis using a new generation of portable high-tech quantum sensor devices.

We study vibrational and electronic properties of tin selenide (SnSe) nanowires encapsulated in single walled carbon nanotubes (SWCNT) by combining experimental Raman spectroscopy and density functional theory (DFT) calculations at the Heyd-Scuseria-Ernzerhof (HSE) level. The theoretically investigated standalone SnSe nanowires are Sn4Se4 with square (2 x 2) atomic arrangement and Sn6Se6 with a repeating hexagonal Mo6S6-like structure. Raman data support the theoretical prediction that the square (2 x 2) nanowires possess specific modes at 151 and 185 cm(-1), whereas the hexagonal Sn6Se6 structure is characterized by a mode appearing at similar to 235 cm(-1). Calculations predict that the (2 x 2) nanowire has an electronic gap of 1.5 eV and the Sn6Se6 nanowire presents a semi-metallic character. Raman spectra of composite SnSe@SWCNT samples show that the radial breathing mode of the nanotubes is strongly suppressed indicating interaction between SWCNT and the encapsulated SnSe nanowire while the Fano asymmetry parameter of the G band is increased.

The common approach to modify the thermoelectric activity of oxides is based on the concept of selective metal substitution. Herein, we demonstrate an alternative approach based on the formation of multiphase composites, at which the individual components have distinctions in the electric and thermal conductivities. The proof-of-concept includes the formation of multiphase composites between well-defined thermoelectric Co-based oxides: Ni, Fe co-substituted perovskite, LaCo0.8Ni0.1Fe0.1O3 (LCO), and misfit layered Ca3Co4O9. The interfacial chemical and electrical properties of composites are probed with the means of SEM, PEEM/XAS, and XPS tools, as well as the magnetic susceptibility measurements. The thermoelectric power of the multiphase composites is evaluated by the dimensionless figure of merit, ZT, calculated from the independently measured electrical resistivity (ρ), Seebeck coefficient (S), and thermal conductivity (λ). It has been demonstrated that the magnitude's electric and thermal conductivities depend more significantly on the composite interfaces than the Seebeck coefficient values. As a result, the highest thermoelectric activity is observed at the composite richer on the perovskite (i.e., ZT = 0.34 at 298 K).

Designing new single-phase white phosphors for solid-state lighting is a challenging trial-error process as it requires to navigate in a multidimensional space (composition of the host matrix/dopants, experimental conditions, etc.). Thus, no single-phase white phosphor has ever been reported to exhibit both a high color rendering index (CRI - degree to which objects appear natural under the white illumination) and a tunable correlated color temperature (CCT). In this article, a novel strategy consisting in iterating syntheses, characterizations, and machine learning (ML) models to design such white phosphors is demonstrated. With the guidance of ML models, a series of luminescent hybrid lead halides with ultra-high color rendering (above 92) mimicking the light of the sunrise/sunset (CCT = 3200 K), morning/afternoon (CCT = 4200 K), midday (CCT = 5500 K), full sun (CCT = 6500K), as well as an overcast sky (CCT = 7000 K) are precisely designed.

A cationic boron dipyrromethene (BODIPY) derivative (1+) has been successfully combined with two polyoxometalates (POMs), the Lindqvist-type [W6O19]2- and the β-[Mo8O26]4- units, into three new supramolecular fluorescent materials (1)2[W6O19]·2CH3CN, (1)2[W6O19], and (1)4[Mo8O26]·DMF·H2O. The resulting hybrid compounds have been fully characterized by a combination of single-crystal X-ray diffraction, IR and UV-vis spectroscopies, and photoluminescence analyses. This self-assembly approach prevents any π-π stacking interactions not only between the BODIPY units, responsible for aggregation-caused quenching (ACQ) effects, but also between the BODIPY and the POMs, avoiding intermolecular charge-transfer effects. Noticeably, the POM units do not only act as bulky spacers, but their negative charge density drives the molecular arrangement of the 1+ luminophore, strongly modifying its fluorescence in the solid state. As a consequence, the 1+ cations are organized into dimers in (1)2[W6O19]·2CH3CN and (1)2[W6O19], which are weakly emissive at room temperature, and in a more compact layered assembly in (1)4[Mo8O26]·DMF·H2O, which exhibits a red-shifted and intense emission upon similar photoexcitation.

Single-phase white phosphors for solid-state lighting are commonly designed using different dopants responsible for emissions in different spectral regions. However, the phenomena of energy transfer and concentration quenching often prevent any clear prediction of the accurate experimental conditions to be selected, leading to a time-consuming trial-and-error discovery process. In this article, a high-throughput experimental approach equipped with machine learning (ML) enabling an efficient identification of the experimental conditions for designing a white phosphor is demonstrated. Li2BaSiO4:Eu,Ce was selected to illustrate this strategy. A total of 88 samples were prepared from the initial synthesis of eight compounds with different concentrations of dopants followed by a post-treatment under a gradient of temperature. The decision tree model identified the experimental conditions for designing a white emission. The analysis of the experimental conditions to obtain other colors of emission, which were also identified by ML, enabled rationalization of the different mechanisms of energy transfer between dopants.

The 7,7,8,8-tetracyanoquinodimethane (TCNQ) radical anion salt compound was used as the sensitive material of gas point contact sensors. The phase composition and surface morphology of the obtained sensor films were established. It was found correlation between surface morphology of the point-contact transducer and definite type of the sensor response curve observed under action of the human breath gas. If the sensor sample is formed from numerical crystals of the same or similar sizes having a uniform shape, similar to a shell, and clearly defined external borders it indicates to the creation of defect-free Yanson point contacts in the process of soft electrochemical synthesis. As a result, the surface of the sensor is a complex multistructure of a numerous number of Yanson point contacts, which generates a large output signal from the sensor in response to the action of the analyte. When crystals of Cu-TCNQ compound forming samples under investigation have lower density, large size, distorted and full of fractures boundaries, it prevents the formation of high-quality point contacts. These morphologic peculiarities are typical for samples with low level of response signal. In the case of extremely low density of Cu-TCNQ crystals observed in the sample surface the sample does not show any response to the action of the human breath gas.

In spite of the strong competition from recently developed nanomaterials such as graphene, carbon nanotubes continue to be promising materials for photovoltaic applications thanks to their structural advantages and cheap prices of synthesis especially the multi-walled carbon nanotubes (MWNT). Mixing of MWNT with a semiconducting polymer such as the P3HT leads to a composite material characterized with enhanced mechanical, thermal and optical properties. In order to investigate the impact of the insertion of different wt% of MWNTs on the luminescence properties of the P3HT we conducted a series of measurements by means of steady state PL and time transient PL for different samples, as well as the study of the temperature effect on these properties. The results obtained confirm the luminescence quenching effect played by the MWNTs, and prove that the lifetime of photo-generated excitons in the P3HT matrix undergoes a modification after the insertion of the MWNTs which means that a charge separation process takes place at the P3HT/MWNT interface.

The newly synthesized oligo[4-(methoxyphenyl) acetonitrile] (OMPA) was chemically modified by Knoevenagel condensation of OMPA oligomer with 9-anthraldehyde. The obtained oligomer is named OMPA-ANTH. Vibrational, optical, and thermodynamic properties of OMPA-ANTH oligomer were investigated using FT-IR, ultraviolet–visible (UV–vis), steady-state and time-resolved photoluminescence spectroscopies, and thermogravimetric analysis (TGA). The chemical insertion of the anthracene group into the OMPA backbone induces a decrease of the optical bandgap and the energy gap (Eg = EHOMO-ELUMO) with significant modification in their observed optical properties. The decay of modified OMPA (OMPA-ANTH) in solution or condensed state is slower than that of pure OMPA, showing a change of the photo-generated species with longer lifetime upon chemical modification.

The synthesized oligo [4-(methoxyphenyl) acetonitrile] (OMPA) was chemically modified by Knoevenagel condensation of OMPA with dimethylformamide dimethyl acetal (DMF-DMA). The obtained oligomer is composed of short chains of poly [3-(dimethylamino)-2-(4-methoxyphenyl)acrylonitrile] and denoted OMFA. Experimental measurements: ultraviolet-visible (UV-vis), steady-state and time-resolved photoluminescence spectroscopies, infrared spectroscopy, and thermogravimetric analysis (TGA), were combined with theoretical calculations, based on density functional theory (DFT) methodologies, to highlight the effect of the grafting of the dimethyl-amine group on the photo-physical and electronic properties of the as-synthesized oligomer. Thus, a redshift of the absorption and photoluminescence spectra is observed upon the chemical grafting of the functional group. Added to that, a decrease of the optical bandgap (Egopt) and the energy gap EH-L=EHOMO-ELUMO occurs upon the chemical modification. DFT computations show that the chemical insertion of the dimethyl-amine group into the monomer and the oligomer induces a drastic change on their frontier orbitals HOMO and LUMO.

A color-tunable phosphor Li2SrSiO4:Eu2+,Eu3+,Ce3+ (LSSO:Eu2+,Eu3+,Ce3+) was synthesized by solid state reaction in reducing atmosphere followed by a controlled heating in air at different temperatures. Due to the different sensitivities to oxidation of the Eu2+ and Ce3+ ions, the emission centers Eu2+/Eu3+/Ce3+ can coexist in the Li2SrSiO4 host and enable a tunable coloration of the "blue-yellow-red" photoemission. By controling the energy transfer between the different activators, a single phase white phosphor was obtained.