Hybrid Materials Based on Carbon Nanotubes and Tetra- and Octa-Halogen-Substituted Zinc Phthalocyanines: Sensor Response Toward Ammonia from the Quantum-Chemical Point of View.

This paper presents the results of quantum-chemical modeling performed by the Density Functional-Based Tight Binding (DFTB) method to investigate the change in the band structure of hybrid materials based on carbon nanotubes and unsubstituted, tetra-, or octa-halogen-substituted zinc phthalocyanines upon the adsorption of ammonia molecules. The study showed that the electrical conductivity of these materials and its changes in the case of interaction with ammonia molecules depend on the position of the impurity band formed by the orbitals of macrocycle atoms relative to the forbidden energy gap of the hybrids. The sensor response of the hybrids containing halogenated phthalocyanines was lower by one or two orders of magnitude, depending on the number of substituents, compared to the hybrid with unsubstituted zinc phthalocyanine.

Thin Films of Chlorinated Vanadyl Phthalocyanines as Active Layers of Chemiresistive Sensors for the Detection of Ammonia.

Halogenated metal phthalocyanines are promising materials for the manufacture of active layers of chemiresistive sensors for the detection of various gases. Despite the high interest in such sensors, there are few systematic studies of the position of halogen substituents in phthalocyanine macroring on the chemiresistive response of their films to gases. In this work, we prepared and studied films of novel tetrachlorosubstituted vanadyl phthalocyanine derivatives with Cl substituents in the peripheral (VOPcCl-p) and nonperipheral (VOPcCl-np) positions of the phthalocyanine ring as active layers of chemiresistive sensors to reveal the effect of the position of substituents on their structure and sensor response to low concentrations of NH.

Cobalt and Iron Phthalocyanine Derivatives: Effect of Substituents on the Structure of Thin Films and Their Sensor Response to Nitric Oxide.

In this work, we study the effect of substituents in cobalt(II) and iron(II) phthalocyanines (CoPcR and FePcR with R = H, F, Cl, tBu) on the structural features of their films, and their chemi-resistive sensor response to a low concentration of nitric oxide. For the correct interpretation of diffractograms of phthalocyanine films, structures of CoPcCl and FePcCl single crystals were determined for the first time. Films were tested as active layers for the determination of low concentrations of NO (10-1000 ppb).

Role of the Cohen-Fano interference in recoil-induced rotation.

We study the rotational dynamics induced by the recoil effect in diatomic molecules using time-resolved two-color x-ray pump-probe spectroscopy. A short pump x-ray pulse ionizes a valence electron inducing the molecular rotational wave packet, whereas the second time-delayed x-ray pulse probes the dynamics. An accurate theoretical description is used for analytical discussions and numerical simulations.

Charge-transfer plasmons of complex nanoparticle arrays connected by conductive molecular bridges.

Charge-transfer plasmons (CTP) in complexes of metal nanoparticles bridged by conductive molecular linkers are theoretically analysed using a statistic approach. The applied model takes into account the kinetic energy of carriers inside the linkers including its dissipation and the Coulomb energy of the charged nanoparticles. The plasmons are statistically investigated for systems containing a large number of complexes of bridged nanoparticles of realistic sizes generated using a simplified molecular dynamics algorithm, where the geometries of the complexes are dependent on the rate of connection of the linkers with the nanoparticles.

Time-resolved study of recoil-induced rotation by X-ray pump - X-ray probe spectroscopy.

Modern stationary X-ray spectroscopy is unable to resolve rotational structure. In the present paper, we propose to use time-resolved two color X-ray pump-probe spectroscopy with picosecond resolution for real-time monitoring of the rotational dynamics induced by the recoil effect. The proposed technique consists of two steps.

Ultrafast dissociation of ammonia: Auger Doppler effect and redistribution of the internal energy.

We study vibrationally-resolved resonant Auger (RAS) spectra of ammonia recorded in coincidence with the NH fragment, which is produced in the course of dissociation either in the core-excited 1s4a11 intermediate state or the first spectator 3a4a11 final state. Correlation of the NH ion flight times with electron kinetic energies allows directly observing the Auger-Doppler dispersion for each vibrational state of the fragment. The median distribution of the kinetic energy release , derived from the coincidence data, shows three distinct branches as a function of Auger electron kinetic energy : + 1.

Hydrogen bond effects in multimode nuclear dynamics of acetic acid observed via resonant x-ray scattering.

A theoretical and experimental study of the gas phase and liquid acetic acid based on resonant inelastic x-ray scattering (RIXS) spectroscopy is presented. We combine and compare different levels of theory for an isolated molecule for a comprehensive analysis, including electronic and vibrational degrees of freedom. The excitation energy scan over the oxygen K-edge absorption reveals nuclear dynamic effects in the core-excited and final electronic states.

Vibrational resonant inelastic X-ray scattering in liquid acetic acid: a ruler for molecular chain lengths.

Quenching of vibrational excitations in resonant inelastic X-ray scattering (RIXS) spectra of liquid acetic acid is observed. At the oxygen core resonance associated with localized excitations at the O-H bond, the spectra lack the typical progression of vibrational excitations observed in RIXS spectra of comparable systems. We interpret this phenomenon as due to strong rehybridization of the unoccupied molecular orbitals as a result of hydrogen bonding, which however cannot be observed in x-ray absorption but only by means of RIXS.

Chlorosubstituted Copper Phthalocyanines: Spectral Study and Structure of Thin Films.

In this work, the tetra-, octa- and hexadecachloro-substituted copper phthalocyanines CuPcCl (where x can equal 4, 8 or 16) were investigated by the methods of vibrational (IR and Raman) spectroscopy and X-ray diffraction. The assignment of the most intense bands, both in IR and Raman spectra, was carried out on the basis of DFT calculations. The structure of a CuPcCl single crystal grown by sublimation in vacuum was refined for the first time.

Fluorinated Metal Phthalocyanines: Interplay between Fluorination Degree, Films Orientation, and Ammonia Sensing Properties.

In this work, the sensor response of MPcF (M = Cu, Co, Zn; = 0, 4, 16) films toward gaseous NH₃ (10⁻50 ppm) was studied by a chemiresistive method and compared to that of unsubstituted MPc films to reveal the effects of central metals and F-substituents on the sensing properties. A combination of atomic force microscopy and X-ray diffraction techniques have been used to elucidate the structural features of thin MPcF films deposited by organic molecular beam deposition. It has been shown that the sensor response of MPcF₄ films to ammonia is noticeably higher than that of MPc films, which is in good correlation with the values of binding energy between the metal phthalocyanine and NH₃ molecules, as calculated by the density functional theory (DFT) method.

Single-incision pediatric endosurgery in newborns and infants.

This study focuses on the successful application of single-incision pediatric endosurgery in the treatment of congenital anomalies and acquired diseases in neonates and infants. The purpose of this scientific review consists in highlighting the spectrum, indications, applicability, and effectiveness of single-port endosurgery in children during the first 3 postnatal months.

Laparoscopic inguinal preperitoneal injection--novel technique for inguinal hernia repair: preliminary results of experimental study.

Background: Inguinal hernia repair is the most common procedure in pediatric surgery. Suture techniques for laparoscopic inguinal hernia repair in children are easy to perform and popular with a low recurrence rate. The aim of this study was to evaluate the effect of laparoscopic preperitoneal injection of three-dimensional gel on closing of the inguinal hernia sac (IHS) in laboratory animals.

Nanotube-derived carbon foam for hydrogen sorption.

A new kind of carbon foam, which is based on the welding of single-walled carbon nanotubes, is built in a computer simulation. Its precisely defined architecture and all atomic positions allow one to perform detailed theoretical analysis of the properties. Such foam is as light as 19 of steel, while its stiffness is similar and nearly isotropic, and it represents a strong three-dimensional material with various possible applications.