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The photoprocesses of diethylamino derivatives of 1,4- and 1,3-distyrylbenzenes in MeCN were studied using absorption, luminescence, 1H NMR, and laser kinetic spectroscopy. Compounds 1 and 2 undergo intersystem crossing to the triplet state and exhibit delayed fluorescence. It was concluded that dye radical anions and radical cations are formed upon dismutation of the triplet state in the presence of an electron donor or acceptor. Quantum mechanical calculations for the structures of diethylamino distyrylbenzenes in the ground and excited states were carried out, making it possible to establish the structures of isomers and the most stable conformers for both compounds. [ABSTRACT FROM AUTHOR]

Fibrin clots are crucial for hemostasis and the healing of wounds; nevertheless, excessive blood clotting plays an important role in many chronic diseases, including cardiovascular disease. In this study, we demonstrated the effect of the prepared AuNPs@PANI core/shell on the formed fibrin network. The synthesis of nanoparticles combining electrically conducting polymers polyaniline (PANI) and gold nanoparticles (AuNPs) is an appealing field of research currently because of their physical features and prospective applications in biochemistry. AuNPs showed surface plasmonic resonance (SPR) properties in the visible region at 520 nm then, after coating with PANI, there was a dramatic red shift to 610 nm. The morphological conformation was confirmed by characterization at the microscopic (TEM, SEM, EDX). The PANI shell plays a crucial role in this system, first enhances the stability of AuNPs core; also, the surface of the PANI shell has positive charges (zeta potential = +17.8 mV), leading to electrostatic interactions with fibrin clots that have negatively charged surfaces. The synthesized core/shell AuNPs@PANI showed good efficiency for degrading fibrin networks under 1:30 h of irradiation by an external source of laser light, which is a result of AuNPs’ ability to absorb light at 520 nm. The degradation of fibrin was observed using a scanning electron microscope (SEM), which showed a clear change in the shape of the network. The appearance of fibrous endings and gaping indicates the beginning of the degradation and melting of the fibrin network in different sites of the clot. Overall, this method could have a major influence on disease states, for example, deep vein thrombosis, through a localized, catheter-based approach.

The spectral and luminescent properties of solutions of bis(hydroxyphenylazomethine)s (I and II) and bis(hydroxynaphthylazomethine)s (III and IV) of the benzene and pyridine series in toluene and ethanol have been studied. The keto–enol equilibrium in pyridine azomethine II in the ground state weakly depends on the presence of the pyridine N atom, whereas the influence of pyridine is significant for pyridine azomethine IV. In solutions of I and II in both solvents, two luminescence bands are observed from the enol (E*) and (K*) keto forms, the ratio of which depends on the excitation wavelength. Luminescence in solutions of III and IV is determined by the formation of K*, and predominant short-wavelength luminescence from E* is added to the luminescence spectrum only in a solution of III in toluene in the case of short-wavelength excitation. The solvent and the pyridine atom were found to affect the position of the emission bands, with the influence being more pronounced for compound II than for IV. For all compounds I–IV, luminescence in alcohol is an order of magnitude more intense than in toluene. [ABSTRACT FROM AUTHOR]

The internal heavy atom effect on the deactivation of triplet states of free porphyrin bases and their metal complexes with Mg(II), Zn(II), Pd(II), and Pt(II) ions in several solvents containing molecular oxygen has been systematically studied. The experiments used laser photolysis techniques and direct measurement of the phosphorescence lifetime of the metal complexes with heavy Pd(II) and Pt(II) ions at 293 K and atmospheric oxygen concentration in solution. The results obtained are compared with previously published data on the laser photolysis of porphyrin metal complexes and a partial discrepancy was found. These data are discussed together with the results of a study of similar compounds in degassed solutions. The triplet state lifetimes of metalloporphyrins at atmospheric oxygen concentration and in deoxygenated solutions were found to be subject to the internal heavy atom effect. The polarity of the solvents used and structural features of the compounds studied were also found to have a significant effect on the triplet states of these porphyrins. [ABSTRACT FROM AUTHOR]

Phototransformations of 6-nitro-8-methoxy-substituted indoline spiropyran in acetonitrile have been studied by laser kinetic spectroscopy (laser photolysis) with single- and double-pulse excitation. The role of the triplet state in the kinetics of photocoloration of spiropyran has been revealed. It has been shown that photochromic transformations of spiropyran involve unstable trans-isomers (conformers) of the open merocyanine form of spiropyran. Data on the transformation kinetics of the trans-isomers are presented. [ABSTRACT FROM AUTHOR]

Advances in chip-scale photonic-electronic integration are enabling a new generation of foundry-manufacturable implantable silicon neural probes incorporating nanophotonic waveguides and microelectrodes for optogenetic stimulation and electrophysiological recording in neuroscience research. Further extending neural probe functionalities with integrated microfluidics is a direct approach to achieve neurochemical injection and sampling capabilities. In this work, we use two-photon polymerization 3D printing to integrate microfluidic channels onto photonic neural probes, which include silicon nitride nanophotonic waveguides and grating emitters. The customizability of 3D printing enables a unique geometry of microfluidics that conforms to the shape of each neural probe, enabling integration of microfluidics with a variety of existing neural probes while avoiding the complexities of monolithic microfluidics integration. We demonstrate the photonic and fluidic functionalities of the neural probes via fluorescein injection in agarose gel and photoloysis of caged fluorescein in solution and in fixed brain tissue. [ABSTRACT FROM AUTHOR]

The developed kinetics of the vibrationally excited states of ozone (with excitation of up to five vibrational quanta), built into the chemical kinetics of O/N/Ar mixtures, was used to model the series of photolysis experiments of V.N. Azyazov et al. The experimental and calculated dynamics of O3 and O2(a1∆) in various O3/O2/Ar mixtures were compared. The dynamics of chemiluminescent radiation of in the titration technique and the applicability of this technique to measuring the dynamics of O atoms in an O3/O2/N2O/Ar mixture were considered. The dynamics of various states of O3(v1,v2,v3) after ozone photolysis was analyzed in detail. The role of these states in the acceleration of the chemical conversion of oxygen components and nitrogen oxides, occurring with competition with ozone vibrational relaxation, was considered. [ABSTRACT FROM AUTHOR]

Photoprocesses in 1,4-diazadistyrylbenzene (1) and 1,3-diazadistyrylbenzene derivative (2) diperchlorates in MeCN were studied by absorption, luminescence, and kinetic laser spectroscopies. For compound 1, trans-cis-photoisomerization and intersystem crossing to a triplet state are observed. For compound 2, photoelectrocyclization is suggested. Quantum chemical calculations of diazadistyrylbenzene structures in the ground and excited states were carried out. The schemes for photoreactions were proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] Fibrin clots are crucial for hemostasis and the healing of wounds; nevertheless, excessive blood clotting plays an important role in many chronic diseases, including cardiovascular disease. In this study, we demonstrated the effect of the prepared AuNPs@PANI core/shell on the formed fibrin network. The synthesis of nanoparticles combining electrically conducting polymers polyaniline (PANI) and gold nanoparticles (AuNPs) is an appealing field of research currently because of their physical features and prospective applications in biochemistry. AuNPs showed surface plasmonic resonance (SPR) properties in the visible region at 520 nm then, after coating with PANI, there was a dramatic red shift to 610 nm. The morphological conformation was confirmed by characterization at the microscopic (TEM, SEM, EDX). The PANI shell plays a crucial role in this system, first enhances the stability of AuNPs core; also, the surface of the PANI shell has positive charges (zeta potential = +17.8 mV), leading to electrostatic interactions with fibrin clots that have negatively charged surfaces. The synthesized core/shell AuNPs@PANI showed good efficiency for degrading fibrin networks under 1:30 h of irradiation by an external source of laser light, which is a result of AuNPs' ability to absorb light at 520 nm. The degradation of fibrin was observed using a scanning electron microscope (SEM), which showed a clear change in the shape of the network. The appearance of fibrous endings and gaping indicates the beginning of the degradation and melting of the fibrin network in different sites of the clot. Overall, this method could have a major influence on disease states, for example, deep vein thrombosis, through a localized, catheter-based approach. [ABSTRACT FROM AUTHOR]

The kinetics of the reaction of hydroxyl radical (OH) with dimethyl methylphosphonate (DMMP, (CH3O)2CH3PO) (reaction 1) OH + DMMP → products (1) was studied at the bath gas (He) pressure of 1 bar over the 295–837 K temperature range. Hydroxyl radicals were produced in the fast reaction of electronically excited oxygen atoms O(1D) with H2O. The time-resolved kinetic profiles of hydroxyl radicals were recorded via UV absorption at around 308 nm using a DC discharge H2O/Ar lamp. The reaction rate constant exhibits a pronounced V-shaped temperature dependence, negative in the low temperature range, 295–530 K (the rate constant decreases with temperature), and positive in the elevated temperature range, 530–837 K (the rate constant increases with temperature), with a turning point at 530 ± 10 K. The rate constant could not be adequately fitted with a standard 3-parameter modified Arrhenius expression. The data were fitted with a 5-parameter expression as: k1 = 2.19 × 10−14(T/298)2.43exp(15.02 kJ mol−1/RT) + 1.71 × 10−10exp(−26.51 kJ mol−1/RT) cm3molecule−1s−1 (295–837 K). In addition, a theoretically predicted pressure dependence for such reactions was experimentally observed for the first time. [ABSTRACT FROM AUTHOR]

Photocatalysis using transition-metal complexes is widely considered the future of effective and affordable clean-air technology. In particular, redox-stable, easily accessible ligands are decisive. Here, we report a straightforward and facile synthesis of a new highly stable 2,6-bis(triazolyl)pyridine ligand, containing a nitrile moiety as a masked anchoring group, using copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) click reaction. The reported structure mimics the binding motif of uneasy to synthesize ligands. Pulse radiolysis under oxidizing and reducing conditions provided evidence for the high stability of the formed radical cation and radical anion 2,6-di(1,2,3-triazol-1-yl)-pyridine compound, thus indicating the feasibility of utilizing this as a ligand for redox active metal complexes and the sensitization of metal-oxide semiconductors (e. g., TiO 2 nanoparticles or nanotubes)., (© 2024 The Author(s). ChemPhysChem published by Wiley-VCH GmbH.)

The self-reaction of acetylperoxy radicals (CH3C(O)O2•) (R1) as well as their reaction with methyl peroxy radicals (CH3O2•) (R2) have been studied using laser photolysis coupled to a selective time resolved detection of three different radicals by cw-CRDS in the near-infrared range: CH3C(O)O2• was detected in the Ã-X˜ electronic transition at 6497.94 cm−1, HO2• was detected in the 2ν1 vibrational overtone at 6638.2 cm−1, and CH3O2• radicals were detected in the Ã-X˜ electronic transition at 7489.16 cm−1. Pulsed photolysis of different precursors at different wavelengths, always in the presence of O2, was used to generate CH3C(O)O2• and CH3O2• radicals: acetaldehyde (CH3CHO/Cl2 mixture or biacetyle (CH3C(O)C(O)CH3) at 351 nm, and acetone (CH3C(O)CH3) or CH3C(O)C(O)CH3 at 248 nm. From photolysis experiments using CH3C(O)C(O)CH3 or CH3C(O)CH3 as precursor, the rate constant for the self-reaction was found with k1 = (1.3 ± 0.3) × 10−11 cm3s−1, in good agreement with current recommendations, while the rate constant for the cross reaction with CH3O2• was found to be k2 = (2.0 ± 0.4) × 10−11 cm3s−1, which is nearly two times faster than current recommendations. The branching ratio of (R2) towards the radical products was found at 0.67, compared with 0.9 for the currently recommended value. Using the reaction of Cl•-atoms with CH3CHO as precursor resulted in radical profiles that were not reproducible by the model: secondary chemistry possibly involving Cl• or Cl2 might occur, but could not be identified.

Quenching of the eosin triplet state by europium(III) in water has been studied in the absence and in the presence of cucurbit[6–8]uril by means of phosphorescence and triplet–triplet absorption in a deoxygenated aqueous solution at room temperature. The quenching is due to photoinduced electron transfer from eosin to europium and to its complexes with cucurbit[6–8]urils. The value of the quenching rate constant of eosin phosphorescence by europium in the absence of cavitands is 1.9 × 106 L mol–1 s–1, whereas in the presence of CB6, CB7, and CB8, the values of the rate constant increase to 2.1, 2.2, and 2.6 × 106 L mol–1 s–1, respectively. Simultaneously with the decrease in the lifetime of the eosin molecule in the triplet state, an increase in the yield of the eosin semioxidized form was observed as a product of photoinduced electron transfer. It has been also shown that with an increase in the concentration of CB7 and CB8, the quenching rate constant increases two times. The difference in the values of the quenching rate constants may be due to the fact that europium, being as a quencher, is present in the form of complexes of different compositions with cucurbit[6–8]urils. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The kinetics of the CH 3 OCH 2 OCH 3 + OH reaction was experimentally studied. • For the first time, rate coefficients at pressures distinctly above 1 bar were determined. • A slight, negative temperature dependence of the rate coefficient was found. • Differences to experimental results obtained at lower pressures are discussed. Abstract The rate coefficient of the reaction of dimethoxymethane with OH radicals was determined in a slow-flow reactor with pulsed laser photolysis/laser-induced fluorescence technique. Temperatures ranged from 297 to 570 K at nominal pressures of 2, 5, and 10 bar (bath gas: helium). The very weak temperature dependence of the obtained rate coefficient can be expressed as: k 1 (T) = (2.9 ± 0.5) × 10−12 exp[(126 ± 61)/ T ] cm3 s−1. A significant pressure dependence was not observed. The results are in very good agreement with literature data for temperatures up to 370 K whereas differences occur at T > 400 K. [ABSTRACT FROM AUTHOR]

In our work, we employed Cs3Bi2I9 as a visible-light-active photocatalyst, synthesized with a low-temperature solvothermal method. The morphological and structural properties of the as-prepared perovskite were investigated, and the results were compared to previous studies to confirm its nature and the quality of the synthesis procedure. Transient absorption spectroscopy was applied in order to investigate the generation and lifetime of photogenerated charge carriers, revealing their formation after visible light excitation. The potential photocatalytic activity of the as-prepared metal halide perovskite was applied for the removal of Rhodamine B in aqueous solution, demonstrating an excellent activity of 93% after 180 min under visible-light irradiation. The current research aims to provide insights into the design of a new visible-light-active photocatalyst, Cs3Bi2I9, selected for its high application value in the field of advanced materials for light harvesting.

Abstract The singlet-singlet and triplet–triplet energy transfer studies between two light harvesting phthalocyanine derivatives namely, zinc tert-butyl phthalocyanine ZnTBPc, and zinc octabutyloxy phthalocyanine ZnOBuPc, have been investigated to mimic the efficient energy-transfer process among the chlorophyll units in the natural photosynthesis. Optical absorption and emission studies showed the strong absorption and fluorescence bands for ZnOBuPc in the NIR region, which are largely red-shifted compared to that of the ZnTBPc. The strong overlap between the emission spectrum of ZnTBPc and the absorption spectrum of ZnOBuPc in toluene suggests the occurrence of the energy transfer from the singlet ZnTBPc (1.80 eV) to the singlet ZnOBuPc (1.59 eV). From the time-resolved fluorescence technique, the rate of energy transfer process was found to be 6.79 × 107 s−1. From the nanosecond laser photolysis measurements, the energy transfer from the triplet ZnTBPc to the lower lying triplet ZnOBuPc was clearly observed with a rate of 5.77 × 105 s−1. These observations suggest the usefulness of the examined combination (ZnOBuPc/ZnTBPc) as a simple model for the artificial antenna in the photosynthetic systems. Graphical Abstract Unlabelled Image Highlights • Good combination for two light harvesting materials • Singlet-singlet energy transfer process between two phthalocyanine units • A simple model for antenna in the artificial photosynthetic systems [ABSTRACT FROM AUTHOR]

The rate constants of the reaction of nitrate and methoxymethyl peroxy, acetonyl peroxy and β-hydroxy (methyl)propylperoxy radicals were measured using laser photolysis coupled with time resolved UV–Visible spectrometry and laser diode spectroscopy over the temperature range 276–356 K, for pressures varying between 280 and 480 Torr and was performed under dry conditions. This work provides the first kinetic data for the reaction of NO 3 + CH 3 OCH 2 O 2 , NO 3 + CH 3 C(O)CH 2 O 2 and NO 3 + (CH 3 ) 2 C(OH)CH 2 O 2 as a function of temperature leading to the following Arrhenius expressions (in cm 3 molecule −1 s −1 ): CH 3 OCH 2 O 2 + NO 3 : k 1 (T) = (1.36 ± 0.70) × 10 −11 exp (-(435 ± 150/T)) CH 3 C(O)CH 2 O 2 + NO 3 : k 2 (T) = (5.47 ± 1.66) × 10 −12 exp (-(282 ± 95/T)) (CH 3 ) 2 C(OH)CH 2 O 2 + NO 3 : k 3 (T) = (1.60 ± 1.27) × 10 −11 exp (-(480 ± 255/T)) These reactions between NO 3 and RO 2 radicals exhibit a low positive temperature dependence over the temperature range 276–356 K indicating that the initiation step involved in the reaction between RO 2 and NO 3 is carried out without an activation barrier. The effect of the peroxy radical structure on the kinetic of its reaction with nitrate radicals is relatively low. We also provide a brief discussion concerning the contribution of this process on the atmospheric elimination of RO 2 in the atmosphere. [ABSTRACT FROM AUTHOR]

Carbon-encapsulated molybdenum nanoparticles were synthesized by laser-assisted photolysis of gaseous precursors. In the proposed method, gas mixtures containing various hydrocarbons and molybdenum hexacarbonyl vapor diluted in argon were irradiated with a nanosecond pulsed UV laser at room temperature. Particle samples were analyzed by transmission electron microscopy (TEM), electron microdiffraction (EMD), energy-dispersive X-ray spectroscopy (EDS), and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) techniques to observe the morphology and composition of the Mo/C nanoparticles. The influence of the type of hydrocarbon, its mole fraction, and the number of UV laser pulses on the resulting nanoparticles was investigated. The nanoparticles were heavily aggregated and consisted of Mo-based cores surrounded by carbon. The type of hydrocarbon did not have any visible effects on the nanoparticle structure and the size of the Mo-based cores or aggregates. Increasing the hydrocarbon mole fraction in the precursor mixture led to an increase in the carbon content and decrease of the Mo-based core size. Increasing the number of UV laser pulses led to larger Mo cores. [ABSTRACT FROM AUTHOR]

Photocoloration and complexation reactions of pyridine-containing nitrosubstituted spiropyran with terbium, zinc, and lanthanum cations in acetonitrile have been studied using laser kinetic spectroscopy. The triplet state participates in the photocoloration reaction of spiropyran. The complexation reaction is accompanied by a hypsochromic shift of the absorption band and proceeds in the microsecond range with pseudo-first order rate constants of 1.4 × 106, 2.3 × 106, and 3.5 × 105 s-1 for lanthanum, zinc, and terbium cations, respectively. [ABSTRACT FROM AUTHOR]

Anthraquinones have been the subject of numerous photochemical studies and their photopolymerization activities have been examined under various conditions to improve more efficient photochemical systems. This article involves further detailed investigations into the photophysical, photochemistry and photopolymerisation properties of 4 commercial derivatives of 2-substituted anthraquinone, namely, 2-Bromomethylanthraquinone (2BA), 2-Chloromethylanthraquinone (2CA), 2-Ethylanthraquinone (2EA), 2-Hydroxymethylanthraquinone (2HA) and one novel synthesized anthraquinone, 2-Acryloxymethylanthraquinone (2AA). 2AA is synthesized from 2HA. The results from both spectroscopic and analysis studies proved the 2AA to having the ester link. Absorption spectroscopy and solvent shift data are used to characterise their spectral activity. Luminescence studies involving fluorescence and phosphorescence analysis indicates efficient intersystem crossing to triplet state and n-π* nature of the lowest excited triplet state. The polymerisation activity was studied using methyl methacrylate (MMA) and analysis of the cure rate was measured using the gravimetric method. All the compounds are shown to be highly dependent on the structure. However, the rate of polymerisation (Rp) was reduced in the presence of amine. This is consistent with other results, proving the behaviour of derivatives with n-π* configuration. Hardness tests for all compounds took place using a different formula of acrylated resin/monomer systems. The excited state characteristics of the methyl derivatives have also been examined using micro and nanosecond flash photolysis. Triplet absorption spectra of all the anthraquinone derivatives show a significant red shift in the region of 340–370 nm with increasing solvent polarity due to stabilisation of the lowest triplet state by solvent reorganization. Hydrogen atom abstraction takes place in 2-propanol, forming a semiquinone radical. In the presence of the tertiary amine, triethylamine, all anthraquinone derivatives show the formation of intermediary species related to either the exciplex or the radical ion pair. Under aerobic conditions, the first decay rate for all anthraquinone derivatives increases and showed oxygen to be a good quencher with a bimolecular rate constant of around 2 × 10 8  mol. dm −3  s −1 . Relative to benzophenone, the molar absorption coefficient, ε, and quantum yield of intersystem crossing, Φ ISC were calculated, and it is summarised that the value for Φ ISC for all compound is less than 1.00 and controls to a major extent their photochemical activities. [ABSTRACT FROM AUTHOR]

Objectives We previously reported that masseter motoneurons (MMNs) and digastric motoneurons (DMNs) in postnatal day (P) 1–5 rats receive convergent inputs from the lateral (l-) and medial (m-) supratrigeminal regions (SupV), intertrigeminal region (IntV), and dorsal region of the principal sensory trigeminal nucleus (PrV). The l-SupV sends burst inputs predominantly to the MMNs. We compared the synaptic inputs to P9–12 rat MMNs and DMNs with those found in the previous study involving P1–5 rats. Methods We performed whole-cell recordings and laser photolysis of caged glutamate in the MMNs and DMNs of P9–12 rats. Results Similar to P1–5 rats, the photostimulation of multiple regions within the l-SupV, m-SupV, IntV, and dorsal PrV, induced postsynaptic currents (PSCs) in both P9–12 MMNs and DMNs. Photostimulation induced predominantly low-frequency PSCs in both P9–12 motoneurons, whereas l-SupV photostimulation predominantly induced burst PSCs in P1–5 rats. However, when the caged glutamate concentration was doubled, l-SupV photostimulation evoked burst PSCs in all P9–12 MMNs. Furthermore, l-SupV and m-SupV photostimulation evoked burst or low-frequency PSCs at significantly higher rates in the MMNs compared to in the DMNs. Conclusions These results suggested that, similar to P1–5 motoneurons, both P9–12 motoneurons received convergent inputs from the SupV, IntV, and PrV; however, the input–output gains of some of the premotor neurons decreased. These synaptic input changes may contribute to the proper development of chewing. [ABSTRACT FROM AUTHOR]

Spectral, luminescent and time-resolved characteristics of 2,5-dibenzylidenecyclopentanone and its symmetrical derivatives (bis( N,N-diethylamino-), dimethoxy-, tetramethoxy-, dimethylthio-, and bis-18- crown-6 derivative) have been studied in media of different polarity (cyclohexane, toluene, acetonitrile, DMSO, and methanol) at room temperature. The absorption maximum of dibenzylidenecyclopentanone shifts bathochromically by 15 nm with an increase in polarity of the medium (cyclohexane-methanol). The introduction of electron-donating substituents in the aromatic rings of dibenzylidenecyclopentanone also results in a bathochromic shift of the absorption maximum by 100-130 nm in the media of different polarity and shifts the fluorescence maximum by 130 nm relative to the maximum of the dimethoxy derivative. Upon laser irradiation of oxygen-free solutions of dibenzylidenecyclopentanone and its tetramethoxy- and bis-18-crown-6 derivatives in acetonitrile, the triplet state with a half-life time of 0.3-1 μs is generated. For dimethoxy-, dimethylthio-, tetramethoxy-, and bis-18-crown-6 derivatives of dibenzylidenecyclopentanone, the isomers with a lifetime of ~50 ms are formed. [ABSTRACT FROM AUTHOR]

Direct photogeneration of excited triplet states of thiophenol and its derivatives is substantially influenced by substitutions and structural changes. In this study the impact of the methyl substituent of thioanisole (a derivative of thiophenol, denoted as PhS- Me ) relative to the basic molecular structure (PhS- H ) on the dynamics of thioanisole triplet and its features has been explored by direct excitation (λ exc. = 266 nm) and by sensitization. The T 1 -T n absorption spectrum is characterized by three bands peaking at 320 nm, 360 nm and 490 nm. The triplet reactivity with triplet quenchers was determined and the triplet energy level was identified by sensitization with beta-carotene, naphthalene, and benzophenone using laser photolysis as well as solvent benzene using pulse radiolysis. The results indicate that the replacement of the hydrogen atom by the methyl substituent leads to a significant change in the thioanisole triplet properties (τ (PhSMe(T1)) = 1.20 μs, ϕ T(PhSMe) = 0.35, 353 kJ mol −1 > E (PhSMe(T1)) > 287 kJ mol −1 ) compared with those of thiophenol (τ (PhSH(T1)) = 40 ns, ϕ T(PhSH) = 0.00, E (PhSH(T1)) = 248 kJ mol −1 ). [ABSTRACT FROM AUTHOR]

Photoinduced processes in bis(diethylaminobenzylidene)cyclohexanone (CH1) and its bis(aza-18-crown-6) derivative ( CH2) in acetonitrile at ambient temperature and 77 K have been studied. The absorption, fluorescence, and phosphorescence spectra of CH1 and CH2 are similar. The probability of the formation of the triplet state is higher for CH2 molecules (λ = 660 nm, lifetime τ ~ 20 μs). The lifetime of the CH1 molecule in the triplet state is estimated at τ ~ 2-3 μs. Photoisomers of CH1 and CH2 are formed along with the triplet state. According to DFT calculation results, the formation of trans-cis photoisomers of CH1 and CH2 is the most energetically favorable. [ABSTRACT FROM AUTHOR]

The degree of ozone recovery after pulsed UV laser photolysis of O-O-Ar mixture is measured using time-resolved absorption spectroscopy. The effect of incomplete ozone recovery in the presence of molecular singlet oxygen O( aΔ) and atomic oxygen is detected. This effect is caused by the reaction between the vibrationally excited ozone molecule formed due to recombination and atomic oxygen. The branching factor for the chemical channel of reaction products is γ = 0.81 ± 0.13. [ABSTRACT FROM AUTHOR]

The effect of cucurbit[7,8]urils (CB7, CB8) on photoprocesses in indocarbocyanine dyes has been studied. Complexation with CB7 and CB8 reveals bathochromic shifts of the maxima in the absorption and fluorescence spectra. Fluorescence enhancement and decreasing have been observed for the complexes with CB7 and CB8, respectively. The dyes and their complexes are capable of trans-cis photoisomerization and hardly undergo intersystem crossing to the triplet state. The rate of the thermal cis-trans isomerization reaction is decreased due to complexation. [ABSTRACT FROM AUTHOR]