Correction: The influence of diameter of multiwalled carbon nanotubes on mechanical, optical and electrical properties of Langmuir-Schaefer films.

Correction for 'The influence of diameter of multiwalled carbon nanotubes on mechanical, optical and electrical properties of Langmuir-Schaefer films' by Karol Rytel et al., Phys. Chem. Chem. Phys., 2020, DOI: .

The influence of diameter of multiwalled carbon nanotubes on mechanical, optical and electrical properties of Langmuir-Schaefer films.

In this paper results of a study of mechanical, optical and electrical properties of thin films made of multiwall carbon nanotubes (MWCNT) of various types were reported. The MWCNT films were obtained on quartz substrates using the Langmuir-Schaefer (LS) method. A gradual increase in transmittance was recorded with decreasing diameters of MWCNT used. Moreover, a blue shift of the π-plasmon band position was observed with increasing MWCNT diameter. In all tested films, anisotropy of electrical surface resistivity was revealed, which was more pronounced for MWCNT of low diameters, except for the MWCNT sample of the smallest diameters. Results of oscillatory barrier measurements of various MWCNT films at the air water interface were used to calculate the complex compression and shear moduli. It is worth emphasizing that the values of these moduli were obtained for the first time for carbon nanotubes films. Moreover, the obtained results allowed identification of the main factor blocking the alignment process, which turned out to be the shear loss tangent.

The impact of solvents on the singlet and triplet states of selected fluorine corroles - absorption, fluorescence, and optoacoustic studies.

This paper examines the influence of aprotic solvents on the spectroscopic properties as well as the energy deactivation of two free-base corrole dyes substituted with C6F5 and/or 4-NO2C6H4 groups. Absorption, fluorescence and laser-induced optoacoustic spectroscopy have been used to follow the singlet and triplet states of fluorine corroles belonging to the A2B and A3 type in toluene (TL), chloroform (CL), dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and also in solvent mixtures. Changes in the absorption and fluorescence spectra are influenced by the type of solvent mixture. The fluorescence behaviors of the two investigated corroles were extremely different - fluorescence of the nitro-corrole in TL is dramatically quenched in the presence of DMF. In contrast, fluorescence quenching of fluorine corroles in DMF-TL mixtures is substantially weakened. Absorption, fluorescence, triplet population as well as singlet oxygen generation parameters are evaluated. The spectral experimental data are supported by quantum chemical calculations - time-dependent density functional theory (TD-DFT) and cyclic voltammetry experiments. The presented results are discussed from a viewpoint of aggregation, tautomerization, and deprotonation effects occurring in the corroles.

New meso-substituted corroles possessing pentafluorophenyl groups--synthesis and spectroscopic characterization.

The investigation presented in this paper deals with new free-base corroles substituted with different peripheral groups. These aromatic macrocycles were efficiently synthesized by a [2+1] approach from dipyrromethanes. Moreover, the basic spectroscopic studies of the dyes in chloroform were conducted, and the UV-Vis absorption, fluorescence and ESR parameters were estimated. The experimental data were supported by quantum chemical calculations. The presence of monomeric dye structures is concentration independent (10(-6)-10(-4) M), as expected for dyes in a solvent of low polarity, and rules out aggregate formation of corroles dissolved in chloroform. The excitation emission and fluorescence life-time values confirm the monomeric structure of the corroles. The spectra were compared with the time-dependent density functional theory (TD-DFT) results for the HOMO-LUMO states. The ESR examinations strongly show that for any type of studied fluorine corrole an unpaired electron is localized on the corrole macroring but not on the substituents both before and after light illumination. Laser illumination creates additional radicals, however with different effectiveness depending on the sample.

Triplet behavior in weakly coupled chromophors in covalent pyridyl porphyrin-polymer systems.

The photophysical properties of the 5-(4-pyridyl)-10,15,20-tri(4-methyloxyphenyl)porphyrins covalently linked to polyethylene glycol - PEG of different molecular weights (35000, 20000 and 8000) dissolved in dimethylsulfoxide were studied. The singlet and triplet states of the porphyrin species behavior were discussed in terms of fluorescence and thermal relaxation processes. The absorption, fluorescence and photothermal experiments showed that in the porphyrins linked to the PEG systems in dimethylsulfoxide the dye moieties occur in weakly interacting dimers. The triplet state enhancement in the 5-(4-pyridyl)-10,15,20-tri(4-methyloxyphenyl)porphyrins covalently linked to PEG was discussed. It was shown that even that the weak interaction of the porphyrin species in the covalent systems with PEG is not detectable by the absorption and only slightly by fluorescence, it is possible to be performed by the complementary spectroscopic methods like photoacoustics and photothermal time resolved spectroscopy.

Time-resolved photocurrent generation in a photoelectrochemical cell with phthalocyanine.

The kinetics of photocurrent generated in the photoelectrochemical cell (PEC) with phthalocyanine (Pc) dyes in the microsecond time scale was discussed. The shape of the kinetics is rather complex and it was discussed in terms of molecular phenomena and electrochemical processes occurring after laser flash illumination. Time constants were calculated from the photocurrent decay curves and at least three time components were well recognized (rise in 0.40 micros, declining in 0.40-0.45 micros and secondary increase in about 2 micros). The shape of the kinetics was discussed in terms of dye singlet and triplet state participation in photocurrent generation and also in terms of creation of the Helmholtz-Goy double layer at the dye layer-semiconductor interface. The alteration in shape of the Helmholtz-Goy double layer in photoelectrochemical cell after laser pulse was also discussed.

Non-radiative deactivation pathways of subphthalocyanine and subnaphthalocyanine dyes and of their mixture.

Subphthalocyanine and subnaphthalocyanine dyes and their mixture were investigated by means of the spectroscopic and photoelectric methods. Absorption, fluorescence, steady-state and time-resolved photothermal measurements for the dyes and their mixture were done in order to get information about the radiative and non-radiative deactivation processes as competetive processes to charge separation. It was shown that energy transfer between the dyes improved the photocurrent generation in photoelectrochemical cells (PEC) based on In(2)O(3) and SnO(2) as an electrode. The possible participation of the dye triplet states in non-radiative processes was discussed.

The influence of pH on charged porphyrins studied by fluorescence and photoacoustic spectroscopy.

We have studied the influence of solvent acidity on the aggregation/protonation behaviour of two charged tetraphenylporphyrins: positively charged tetrakis(N,N,N-trimethylanilinium-4-yl)porphyrin (TAP) and negatively charged tetrakis(4-sulfonatophenyl)porphyrin (TPPS4). Spectroscopic measurements (absorption, fluorescence, excitation and photoacoustic) have been made to follow the radiative and nonradiative relaxation processes of excited dye molecules at various pH values. The ability of these porphyrins to exist in aggregated and protonated forms was also investigated. It has been shown that TPPS4 exists in at least three spectroscopic forms: monomer (M1), dication (D1) and aggregated dication (AD), whereas TAP exists in two forms: monomer (M2) and dication (D2). These forms are characterised by different absorption and fluorescence properties. The short wavelength forms of the dyes (M1 and M2) were assigned to the monomeric forms and D1 and D2 were assigned to the protonated forms of TPPS4 and TAP, respectively; AD was identified as the aggregate of the protonated form of TPPS4. Each form shows deactivation of its excited state by nonradiative pathways-particularly high thermal deactivation was observed for the aggregates of the protonated form. Energy transfer between the monomeric form and the dication form has been demonstrated and Förster radii have been estimated (R0 = 31 and 44 A for TAP and TPPS4, respectively). Since protonation and aggregation of photoreceptors can strongly affect their photosensitizing effects (e.g. cellular uptake, singlet oxygen production) the results presented here may be important in the study of the function of photosensitizers in tumour tissues because, as is already known, the microenvironment in cancerous tissue is more acidic than in healthy cells.