Vol 51, No 6 (2017)

The two-quantum photochemistry of aqueous solutions of cis,trans-[Pt^IV(en)(I)₂(CH₃COO)₂] (complex 1) has been studied by laser flash photolysis using an irradiation wavelength of 355 nm. This compound can be considered as a model representative of the mixed-ligand Pt(IV) complexes tested for use in photodynamic therapy. The appearance of transient absorption, presumably due to two consecutively produced Pt(III) complexes, has been revealed. The spectral and kinetic characteristics of the intermediates have been determined. A mechanism of two-quantum photolysis of complex 1 is proposed on the basis of the data obtained.

The dark process (posteffect) of increasing the electrical conductivity and spectral absorption in the graphene oxide (GO) film after its preliminary UV irradiation has been studied. The posteffect is due to the conformational relaxation of the structure (flattening) of GO nanosheets after the UV-induced dissociation of oxygen-containing groups. At room temperature, the relaxation time is τ ≈ 300 h and the activation energy in the range of 20–70°C is E_a ≈ 0.6 eV.

The condensation of supersaturated vapors of various substances in air under UV irradiation in a cloud chamber has been studied. The irradiation and subsequent photodissociation greatly facilitate the condensation of vapors in comparison with unirradiated mixtures, wherein both a vapor that directly absorbs radiation (direct photoinduced phase transition) and, for example, water vapor in the presence of photodissociating impurities (indirect photoinduced transition) can be condensed.

Thiacarbo- and thiadicarbocyanine indolenine and thiazoline polymethine dyes form host‒guest complexes with cucurbit[7,8]urils in water. Cucurbit[7]uril forms preferentially 1: 1 and 1: 2 monomeric complexes and cucurbit[8]uril forms 2: 1 and 2: 2 dimeric complexes. On the basis of quantum-chemical calculations, the structure of monomeric and dimeric complexes has been suggested. The complexation manifested itself in absorption, prompt and thermally activated delayed fluorescence spectra, as well as in the triplet‒triplet absorption spectra. Dimeric complexes in the triplet state are involved in one-electron oxidation and participate in triplet‒triplet energy transfer.

Förster resonance energy transfer between InP@ZnS hydrophobic colloidal quantum dots of two different sizes has been studied in the closely packed nanoclusters formed spontaneously in an organic solvent upon the addition of a precipitating solvent. The quantum dots had a core@shell structure and were stabilized by dodecylamine ligands.

We report theoretical doubly differential and integrated cross sections for electron elastic scattering by hydrogen chloride as well as by hydrogen fluoride over wide impact energies ranging from 10 eV up to 20 keV, where the non-relativistic theory is available. The calculations are performed by considering a target molecular state described by means of single-center molecular wave functions within the partial-wave formalism by means of a spherical optical potential model taking into account a static contribution deduced from a single-center Hartree-Fock target description as well as fine effects, like correlation-polarization and exchange contributions. The theoretical results obtained in this model pointed out clearly the role played by the exchange and correlation-polarization potentials, particularly at lower incident energies. The numerical results, obtained in this parameter free model for both doubly differential and integral cross sections for electron scattering by HCl and HF molecular targets, are compared with the available experimental data and satisfactory agreements are observed in the whole energy range.