Nature Of Electronic Transitions Research Articles

Instantaneous Marcus theory for photoinduced charge transfer dynamics in multistate harmonic model systems

Modeling the dynamics of photoinduced charge transfer (CT) in condensed phases presents challenges due to complicated many-body interactions and the quantum nature of electronic transitions. While traditional Marcus theory is a robust method for calculating CT rate constants between electronic states, it cannot account for the nonequilibrium effects arising from the initial nuclear state preparation. In this study, we employ the instantaneous Marcus theory (IMT) to simulate photoinduced CT dynamics. IMT incorporates nonequilibrium structural relaxation following a vertical photoexcitation from the equilibrated ground state, yielding a time-dependent rate coefficient. The multistate harmonic (MSH) model Hamiltonian characterizes an organic photovoltaic carotenoid-porphyrin-fullerene triad dissolved in explicit tetrahydrofuran solvent, constructed by mapping all-atom inputs from molecular dynamics simulations. Our calculations reveal that the electronic population dynamics of the MSH models obtained with IMT agree with the more accurate quantum-mechanical nonequilibrium Fermi’s golden rule. This alignment suggests that IMT provides a practical approach to understanding nonadiabatic CT dynamics in condensed-phase systems.

Comparative analysis of the optical and electrical properties of PVA/PVP blended polymer with ZnCo2O4/CdS nanocomposites for optoelectronic and dielectric capacitor applications

Polymer nanocomposite blends were produced using solution casting, hydrothermal and thermolysis techniques. The blends were composed of a polymer blend consisting of polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) as the organic host matrix with (1−x)ZnCo2O4–xCdS as filler samples. The current study investigated the morphological, structural, optical, and dielectric features of PVP/PVP/(1-x)ZnCo2O4/xCdS blends. The crystallite size and the phases formed in the fillers were obtained using Rietveld method. The structure and morphology of blended samples were studied using X-ray diffraction and scanning electron microscope techniques. The results of the optical properties imply that the linear and nonlinear optical parameters were affected by the amount of CdS in the (1-x)ZnCo2O4/xCdS filler samples. The direct allowed, indirect allowed, direct forbidden and indirect forbidden transitions values were reduced to 5.09, 4.55, 4.67 and 4.12 eV, respectively, as (1-x)ZnCo2O4/xCdS with x = 0.05 was incorporated into the PVA/PVP blend. The nature of electronic transitions in all blends were also studied. The fluorescence intensity, emitted colors and purity of the doped PVA/PVP blend are affected by the amount of CdS in the fillers and the excitation wavelength. The energy density of the host blend was improved as it loaded with fillers contained 5 and 10 % CdS in the frequency range beyond 1 kHz. The relaxation times of all doped blends were diminished except blend contained 25% CdS, the relaxation time rose slightly as compared with the relaxation time of undoped blend. The obtained properties indicates potential utility of the doped blends in photocatalytic, photonic, storage energy and optoelectronic applications.

Synthesis and Characterization of Isostructural Th(IV) and U(IV) Pyridine Dipyrrolide Complexes.

A series of pyridine dipyrrolide actinide(IV) complexes, (MesPDPPh)AnCl2(THF) and An(MesPDPPh)2 (An = U, Th, where (MesPDPPh) is the doubly deprotonated form of 2,6-bis(5-(2,4,6-trimethylphenyl)-3-phenyl-1H-pyrrol-2-yl)pyridine), have been prepared. Characterization of all four complexes has been performed through a combination of solid- and solution-state methods, including elemental analysis, single crystal X-ray diffraction, and electronic absorption and nuclear magnetic resonance spectroscopies. Collectively, these data confirm the formation of the mono- and bis-ligated species. Time-dependent density functional theory has been performed on all four An(IV) complexes, providing insight into the nature of electronic transitions that are observed in the electronic absorption spectra of these compounds. Room temperature, solution-state luminescence of the actinide complexes is presented. Both Th(IV) derivatives exhibit strong photoluminescence; in contrast, the U(IV) species are nonemissive.

Investigation the Effect of Thermal Agent on Physical Properties of PVC-PVA Blended

In this study, the optical characteristics of polyvinyl chloride(PVC), polyvinyl alcohol (PVA) and binary PVA - PVC blend films at various concentrations PVA75% + PVC25%, PVA50% + PVC50%, and PVA25% + PVC 75% are examined in relation to temperature variations 25, 120 and 140 °C for 1 hour. The binary blend films of polyvinyl chloride and polyvinyl alcohol were produced using casting techniques. UV-visible spectroscopy used to determine the optical properties of the films in the wavelength range (200-900) nm, such as transmittance, absorbance, absorption coefficient and energy gap as well as the impact of temperature on these parameters, were measured and examined. The results of the experimental part demonstrated that the absorption and absorption coefficient of binary PVA - PVC blend films at various concentrations increased with increased concentration of polyvinyl alcohol (PVA) polymer. The energy gap of binary PVA-PVC blend films at various concentrations decreased with increased concentration of polyvinyl alcohol (PVA). The ratio of (PVA 75%+ PVC25%) binary blend has extremely suitable optical characteristics. The absorption and absorption coefficient of binary PVA-PVC blends increased with increased temperatures. While the transmission and energy gap of binary PVA-PVC blend films were decreased as the temperature was raised. The nature of electronic transitions of binary PVA - PVC blend films at various concentrations before and after exposure to temperatures is indirect. From the results obtained from the experimental part, it concludes that the absorption and absorption coefficient of binary PVA - PVC blend films are better than pure polyvinyl chloride and polyvinyl alcohol polymers. The optical characteristics of binary PVA - PVC blend films effect by exposure to temperatures.

Gas-Phase Electronic Structure of Phthalocyanine Ions: A Study of Symmetry and Solvation Effects.

Research into and applications of phthalocyanines (Pc) are mostly connected to their intriguing electronic properties. Here, messenger-type UV-vis spectroscopy of two metal-free ions from the phthalocyanine family, cationic H2Pc+ and H2PcD+, along with their hydrates is performed. They show that the electronic properties of both ions can be traced to those in the conjugate base, Pc2-, however, they are affected by state splitting due to the reduced symmetry; in the H2Pc+ radical cation, a new band appears due to excitations into the singly-occupied molecular orbital. Quantum chemical spectra modeling reproduces all important features of the measured spectra and provides insight into the nature of electronic transitions. Hydration of the ions has only a mild effect on the electronic spectra, showing the stability of the electronic structure with respect to solvation effects.

Continuous Scatterplot Operators for Bivariate Analysis and Study of Electronic Transitions.

Electronic transitions in molecules due to the absorption or emission of light is a complex quantum mechanical process. Their study plays an important role in the design of novel materials. A common yet challenging task in the study is to determine the nature of electronic transitions, namely which subgroups of the molecule are involved in the transition by donating or accepting electrons, followed by an investigation of the variation in the donor-acceptor behavior for different transitions or conformations of the molecules. In this paper, we present a novel approach for the analysis of a bivariate field and show its applicability to the study of electronic transitions. This approach is based on two novel operators, the continuous scatterplot (CSP) lens operator and the CSP peel operator, that enable effective visual analysis of bivariate fields. Both operators can be applied independently or together to facilitate analysis. The operators motivate the design of control polygon inputs to extract fiber surfaces of interest in the spatial domain. The CSPs are annotated with a quantitative measure to further support the visual analysis. We study different molecular systems and demonstrate how the CSP peel and CSP lens operators help identify and study donor and acceptor characteristics in molecular systems.

INFLUENCE OF CELLULOSE FILM THICKNESS ON OPTICAL CHARACTERISTICS

In this study, cellulose was precisely and scientifically extracted, allowing for the production of thin films that were made using the Spin Coating technique, well been studied Zeta analysis is a measurable physical property .A large molecule or matter's surface. It is used to improve the properties of materials such as solutions and proteins, as well as the potential interactions of solutions and surfaces and we studied discovered.influence of film thickness on the optical properties of these films, including their absorbents, Transamination's transmittance, and absorption coefficient (α), Additionally, it is important to understand the quality of the anticipated optical absorbance of these membranes in relation to the wavelengths, photon energy, and the nature of electronic transitions, such as direct or indirect transmissions, between the beams

INFLUENCE OF CELLULOSE FILM THICKNESS ON OPTICAL CHARACTERISTICS

In this study, cellulose was precisely and scientifically extracted, allowing for the production of thin films that were made using the Spin Coating technique, well been studied Zeta analysis is a measurable physical property .A large molecule or matter's surface. It is used to improve the properties of materials such as solutions and proteins, as well as the potential interactions of solutions and surfaces and we studied discovered.influence of film thickness on the optical properties of these films, including their absorbents, Transamination's transmittance, and absorption coefficient (α), Additionally, it is important to understand the quality of the anticipated optical absorbance of these membranes in relation to the wavelengths, photon energy, and the nature of electronic transitions, such as direct or indirect transmissions, between the beams

Rational design of high-performance soluble intrinsic black polyimide with full absorption of visible light

With the rapid development of photoelectric devices, the demand for black polyimide (BPI) with excellent masking ability is growing, but existing BPI doped with black substrates has serious insulation and mechanical performance deficiencies. To solve the problem, the intrinsic BPI with excellent comprehensive performance is highly desirable. In this work, tetraphenylcyclopentadienone (TPCP) was chosen as a chromophore, a novel diamine (TPCPtPPDA) containing TPCP grafted with biphenyl groups was synthesized, and TPCPtPPDA was then polymerized with 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) to obtain a black polyimide (TPCPtPPPI). The TPCPtPPPI showed full absorption of visible light with cutoff wavelength (λcut) high to 713 nm and Commission International Eclairage (CIE) lab color parameter L* of 0.82. By calculating the frontier molecular orbitals and the nature of electron transitions, the excellent light absorption property was attributed to the electron transition from HOMO to LUMO occurring in the diamine moieties, with the charge transfer mainly from the terphenyl moieties in 2 and 5 positions to the central cyclopentadienone core. Meanwhile, TPCPtPPPI also had excellent thermal, electrical and mechanical performances and solubility by introduction of rigid non-planar propeller-shaped structure. This work provides a promising strategy for constructing high-performance soluble intrinsic BPI and related polymers with full absorption of visible light.

The fundamental relation between electrohelicity and molecular optical activity.

Electrohelicity arises in molecules such as allene and spiropentadiene when their symmetry is reduced and helical frontier molecular orbitals (MOs) appear. Such molecules are optically active and electrohelicity has been suggested as a possible design principle for increasing the chiroptical response. Here we examine the fundamental link between electrohelicity and optical activity by studying the origin of the electric and magnetic transition dipole moments of the π-π* transitions. We show that the helical character of the MOs drives the optical activity in allene, and we use this knowledge to design allenic molecules with increased chiroptical response. We further examine longer carbyne-like molecules. While the MO helicity also contributes to the optical activity in non-planar butatriene, the simplest cumulene, we show there is no relation between the chiroptical response and the helical π-MOs of tolane, a simple polyyne. Finally, we demonstrate that the optical activity of spiropentadiene is inherently linked to mixing of its two π-systems rather than the helical shape of its occupied π-MOs. We thus find that the fundamental connection between electrohelicity and optical activity is very molecule dependent. Although electrohelicity is not the underlying principle, we show that the chiroptical response can be enhanced through insight into the helical nature of electronic transitions.

Small‐Molecule Fluorescent Probe: Ratiometric and Selective Detection of Sodium Ions for Imaging and Solid‐State Sensing Applications

AbstractA ratiometric highly fluorescent small molecular probe (L), 1,2,4‐triazol‐4‐yliminomethyl‐5‐(hydroxymethyl)‐2‐methylpyridin‐3‐ol, was designed for detecting Na(I) ions in DMF:water (1 : 9, v/v) medium. The chemical structure of Na(I) complex of probe was confirmed by single crystal XRD. The fluorescence detection of Na+ ion has been executed in both solid and solution medium. The observations suggest the same chemical structure in solution state as well. The detailed photochemical studies showed that highly selective sensing of Na+ ions even in the presence of common interfering K+ ions. The fluorescence decay studies showed that the lifetime of NaL is lesser than L. The excited state intramolecular proton transfer (ESIPT) mechanism and the nature of electronic transitions were examined by quantum chemical studies. The electrochemical behaviour was studied by cyclic voltammetry and impedance spectra. It has also been shown that the probe can be applied to paper based sensing and imaging of Na+ ions in U87 cell lines.

High-pressure synthesis of seven lanthanum hydrides with a significant variability of hydrogen content

The lanthanum-hydrogen system has attracted significant attention following the report of superconductivity in LaH10 at near-ambient temperatures and high pressures. Phases other than LaH10 are suspected to be synthesized based on both powder X-ray diffraction and resistivity data, although they have not yet been identified. Here, we present the results of our single-crystal X-ray diffraction studies on this system, supported by density functional theory calculations, which reveal an unexpected chemical and structural diversity of lanthanum hydrides synthesized in the range of 50 to 180 GPa. Seven lanthanum hydrides were produced, LaH3, LaH~4, LaH4+δ, La4H23, LaH6+δ, LaH9+δ, and LaH10+δ, and the atomic coordinates of lanthanum in their structures determined. The regularities in rare-earth element hydrides unveiled here provide clues to guide the search for other synthesizable hydrides and candidate high-temperature superconductors. The hydrogen content variability in lanthanum hydrides and the samples’ phase heterogeneity underline the challenges related to assessing potentially superconducting phases and the nature of electronic transitions in high-pressure hydrides.

Facile and eco-friendly PVA nanocomposites as a photo-luminescent: Anti-counterfeiting, LED and wettability applications

Novel MoO3:Eu3+ nanopowder (NP) were synthesised by the propellant chemical route. Polymer nanocomposites (PNCs) were prepared by embedding NPs effectively into the mixture of Poly vinyl alcohol (PVA) and Chitosan solution through the solution casting technique (SCT). This process was extensively used owing to certain benefits such as uniform dispersion of NPs and easiness of the process. Eu3+ doped MoO3 (2–5 wt %) nanocomposites (NCs) were fabricated. Powder X-ray diffraction analysis indicated single orthorhombic crystal structure of the synthesised NCs and confirmed the integration of the nanophosphor into the polymer blend. Crystallite size was estimated to be ∼17nm using Scherrer's formula. The Fourier transform infrared spectrometer technique was employed to reveal the vibrational bands as well as the intermolecular bonding between the polymer blend and MoO3:Eu3+ NPs. Thermogravemetric analysis showed the enhanced thermal stability of the PNCs with the incorporation of NPs. The nature of electronic transitions was studied by optical bandgap energy from Tauc's relation. The photoluminescence emission spectra were monitored at excitation wavelength of 394 nm and noticed the transitions at wavelengths of 599 nm, 613 nm, 630 nm, 652 nm, and 694 nm belongs to the intense orange-red emissions. The emission colour of the NC films was confirmed by CIE chromaticity diagram. Especially, the NCs complex not only can be uniformly dispersed in the monomer solution and can be acted as both the coordination crosslinking agent and luminophores. Besides, upon the incorporation of Eu3+ into the polymer matrix comprising ammonium group, the adhesive strength as well as the mechanical behaviour of the hydrogel are considerably enhanced. The Eu3+ doped NCs that were developed have a great potential for fabricating efficient optoelectronic devices and luminescent hydrogels. This mechanism was further validated and utilised for application in relief printing and screen printing.

Insights into optical band gap identification in polymer composite films based on PVA with enhanced optical properties: Structural and optical characteristics

In this study, poly(vinyl alcohol) (PVA) was integrated with various amounts of dibismuth trioxide (Bi2O3) to produce PVA:Bi2O3 composites using casting methodology. The influence of Bi2O3 filler loading on the structure of PVA was investigated through the XRD and FTIR approaches. The XRD and FTIR outputs revealed polymer/filler interactions. For all the composite films, the transition of electrons from the filled valence band to empty conduction bands is a complicated subject in condensed matters. Band gap detection is discussed in the aspect of two models to identify the nature of electron transitions as an obscured topic in condensed matter physics. The application of Tauc's model was successful in determining the direct and indirect band gap energies. The band gap of PVA was 6.3 eV and reduced to 3.28 eV upon the insertion of 12 wt% of Bi2O3 filler. With the help of optical dielectric loss versus photon energy, the most probable exponent (γ) value in Tauc's equation was fixed. The wavelength-dependent on the real and imaginary parts of the optical dielectric function and the W-D model were utilized to determine the fundamental parameters, including N/m∗, ε∞, τ, μopt, ωp, ρopt, Ed, Eo and no. The N/m∗ is enhanced from 3.65 × 1055 m3/kg to 42.58 × 1055 m3/kg. The improvement of dispersion energy from 1.36 to 6.71 is evidence of amorphous enrichment in composite films. The W-D model uses the refractive indexes to estimate the optical band gap. The single oscillator parameter (Eo) determined from the W-D model is close enough to the band gap received from the Tauc model.

Na+-doped lead-free double perovskite Cs2AgInCl6 for broadband solar-blind UV detection

As a new generation of photonic materials, lead-free halide double perovskite materials demonstrate strong UV-light excited broadband emission that are promising for solar-blind ultraviolet (UV) light detectors. However, their practical applications are strongly limited by the low photoluminescence quantum efficiency because of the parity-forbidden nature of electronic transitions. Herein, the idea of cation alloying into lead-free halide double perovskite is proposed to mitigate the weak electronic transition and to improve the luminescence yield. By using the hydrothermal method, a series of Cs2NaxAg1-xInCl6 microcrystals were fabricated and the influences of Na-doping on the structural evolution and optical properties are investigated. Notably, the luminescence properties can be greatly improved by introducing an alloying element. By leveraging the UV-to-visible spectral conversion capability of the developed halide crystals, we fabricated a luminescent composite film by incorporating Cs2NaxAg1-xInCl6 perovskite nanocrystals into a polymethyl methacrylate matrix. Using this composite film as a spectral converter, we successfully demonstrated a solar-blind ultraviolet light detector with broadband and efficient response. Our work provides a novel solution for broadband solar-blind UV detection that could have practical implications for commercialization of metal halide based luminescent materials.

RELATİONSHİP BETWEEN ELECTRICAL AND CATALYTIC IN THE REACTION OF CONVERSION OF ETHANOL TO ACETONE

Low molecular weight ketones are among the most important products widely used in industry, however, the existing methods for their production are multistage. The significant disadvantages of these methods include the implementation of individual stages at high temperatures and pressures. As a result, the development of more economical and easy-to-implement processes is presented as an actual task for the basic organic synthesis industry. Recently, ethanol has been considered as a possible feedstock for the production of acetone. The prospect of using ethanol as a feedstock is due to the large renewable resources for its production. The growing interest in recent years in the production of ethanol by processing agricultural products and waste from the food and woodworking industries will undoubtedly stimulate further development of the method of producing acetone from ethanol. The catalytic conversion of ethanol to acetone is a relatively new method for producing acetone and, naturally, the number of publications devoted to this process is relatively small. In previously published works, as a rule, the issues of the mechanism of the process, as well as the relationship between the physicochemical and catalytic properties of the proposed active systems in these reactions, are not considered in detail. Active and selective catalysts were selected for the conversion reaction of ethanol to acetone, the mechanism of the process and the relationship between the physicochemical and catalytic properties of the activated sample were studied. The experiments were carried out on an active catalyst with the composition ZnO:CaO=9:1 The main provisions of the electronic theory of catalysis are developed in application to semi¬con-ductors, since, firstly, the theory of semiconductors is now more developed, and secondly, most of the catalysts used in practice belong to semiconductors. The surface of a semiconductor is the protection of two phases: a solid body-gas. The approach to this boundary from the side of the gaseous environment is essential for catalysis. The environment affects the surface and volume of the solid body. The influence of the environment is carried out through adsorption, as a result, the Fermi level shifts, and the electrophysical pro¬pert¬ies of catalysts change in the processes of adsorption and catalysis. Reactions of heterogeneous-catalytic transformation of low molecular weight alcohols are of great practical importance. The relevance of catalytic transformations of ethanol into various valuable products is the most important task of modern catalytic chemistry. To elucidate the mechanism of these reactions, a necessary step is to study the nature of the electronic interaction of reactants with a solid body, since the vast majority of catalysts of heterogeneous-catalytic oxidation - metal oxides, semiconductors, so especially promising is to involve methods for studying the electro physical properties of the surface. Changing these properties and studying the nature of their change in the atmosphere of the reactants, it is possible obtain valuable information about the nature of the electronic interaction of the reactant-catalyst. The works carried out in this direction showed that in most cases the process of chemisorption is accompanied by the appearance of an additional surface potential, indicating the charging of the surface in the presence of a particular reactant. The electrical and catalytic properties of a series of active zinc-calcium oxide catalysts were studied (their activity was also studied in previous experiments). The study of the electrical properties of the catalyst is of the greatest interest for elucidating the mechanism of reactions, since they can provide information about the nature of electronic transitions that limit the course of the reaction. The number of different factors determines the catalytic activity of a solid body. Each of these factors can correlate with certain properties of a solid body. When comparing catalytic and electrophysical properties electrical conductivity is most often measured. Measuring on the same catalyst sample under the same conditions of conductivity change can provide useful information about mechanism of action of the catalyst and the course of the catalytic reaction. Studies of the electrical conductivity of the synthesized catalysts have shown that all the catalysts studied are semiconductors. This article shows the relationship between the electrical and catalytic properties of zinc-calcium oxide catalysts. Keywords: catalyst, electrical conductivity, activation energy, adsorption, ethanol, acetone.

The nature of electronic transitions and the spectral-luminescent properties of thiopyrylotricarbocyanines

We have made a selection of the leading structures among cationic polymethine dyes with different structures of terminal heterocyclic groups and polymethine chains for passive Q-switch of a diode-pumped solid-state neodymium laser. Such dyes have a maximum absorption in the region of 1060 nm and a minimum absorption in the region of 810 nm. It was found that the 4-((E)-2-((E)-2-chloro-3-(2-(2,6-diphenyl-4H-thiopyran-4-ylidene)ethylidene)cyclohex-1-en-1-yl)vinyl)-2,6-diphenylthiopyrylium tetrafluoroborate dye most closely matches these characteristics. The nature of its long-wavelength and higher electronic transitions was interpreted based on quantum-chemical calculations by the DFT/B3LYP/6-31G (d, p) method and TDDFT taking into account the polarity of the medium by the PCM method. The use of this dye as a laser Q-switch made it possible for the first time to obtain passive mode locking in diode-pumped neodymium lasers.

Engineering of inorganic nanostructures with hierarchy of chiral geometries at multiple scales

Engineering of inorganic nanostructures with hierarchy of chiral geometries at multiple scales

Improvement of the optical characteristics of PVA/PVP blend with different concentrations of SnS2/Fe

AbstractPolyvinyl alcohol (PVA)/polyvinylpyrrolidone (PVP; weight 7:3) polymer blends doped with different ratios (1 wt%, 3 wt%, 5 wt%, and 10 wt%) from nano SnS2/Fe are developed using casting and thermolysis procedures. Rietveld analysis showed that Fe is incorporated into the SnS2 lattice forming a single hexagonal phase with an average crystallite size of 6 nm along [00l] direction and 15 nm along [h00] direction. X‐ray diffraction together with Fourier transform infrared data is used to examine the homogeneity distribution of the nanofiller over the blend matrix. The effect of doping on the absorbance, transmittance, extinction coefficient, refractive index, direct and indirect optical band gaps, and other dispersion parameters of the blend is studied in detail. The nature of electronic transitions in the different blends was determined using Tauc's relation and the dielectric loss parameter. As the weight concentrations of SnS2/Fe dopants increased, the nonlinear optical parameters are increased relative to the undoped PVA/PVP polymer blend. The influence of the different excitation wavelengths and the amount of nanofillers on the fluorescence spectra from different blends are also investigated.

Tricationic asymmetric monomeric monomethine cyanine dyes with chlorine and trifluoromethyl functionality – Fluorogenic nucleic acids probes

The nucleic acids staining ability of a series asymmetric monomeric monomethine cyanine dyes prepared by simple and reliable synthetic procedure is demonstrated. The dyes show ratiometric red shift of their longer wavelength absorption maxima. It is in the range 514–522 nm neat in TE buffer, 516–528 nm in the presence of DNA, and 518–524 nm in the presence of RNA. Practically the target dyes are not fluorescent in water solutions or possess negligible fluorescence, but become strongly fluorescent after contacting with nucleic acids. A considerable increase of the fluorescence intensity upon binding to RNA compared to dsDNA is observed particularly in the group of chlorine substituted analogues 1a-1c. The intensive ICD signal of dye 1a in the presence of RNA unequivocally proves that finding. Molecular docking studies have been performed to investigate the nature of binding mode of the dyes with DNA. 1a-1c are groove binders and 2b-2c are interacting with DNA through partial intercalation mode. The nature of electronic transitions and their manifestation in the electronic spectra are revealed by DFT and TDDFT calculations.