Intense charge transfer plasmons in golden nanoparticle dimers connected by conductive molecular linkers.

Golden nanoparticle dimers connected by conjugated molecular linkers 1,2-bis(2-pyridyl)ethylene are produced. The formation of stable dimers with 22 nm diameter nanoparticles is confirmed by transmission electron microphotography. The possibility of charge transfer through the linkers between the particles in the dimers is shown by the density functional theory calculations. In addition to localized plasmon resonance of solitary nanoparticles with a wavelength of 530 nm, the optical spectra exhibit a new intense absorption peak in the near-infrared range with a wavelength of ∼780 nm. The emergent absorption peak is attributed to the charge-transfer plasmon (CTP) mode; the spectra simulated within the CTP developed model agree with the experimental ones. This resonant absorption may be of interest to biomedical applications due to its position in the so-called transmission window of biological tissues. The in vitro heating of CTP dimer solution by a laser diode with a wavelength of 792 nm proved the efficiency of CTP dimers for achieving a temperature increase of ΔT = 6 °C, which is sufficient for hyperthermia treatment of malignant tumors. This indicates the possibility of using hyperthermia to treat malignant tumors using the material we synthesized.

Spectroscopy of structurally disordered hydrated iron fluoridotitanate in the regions of vibrational and electronic excitations.

Raman and optical absorption spectra of disordered hydrated iron fluoridotitanate (HITF) single crystal were studied. Temperature transformations of the Raman spectra indicate independent ordering processes of the [TiF6]2- and [Fe(H2O)6]2+ complexes below the structural phase transition. The absorption spectrum in the near-infrared and visible ranges includes transitions from the high spin ground state 5T2 of Fe2+ ion to the excited 5E state and a set of excited triplets. Analysis by Tanabe-Sugano method gives crystal field Dq = 490 cm-1 and Racah parameters B = 340 cm-1 and C = 1904 cm-1. Considerable decrease of B parameter as compared to the free ion value indicates a decrease of interelectron repulsion in the disordered neighborhood of Fe2+ ions.

Monoclinic SmAl3(BO3)4: synthesis, structural and spectroscopic properties.

Single crystals of SmAl3(BO3)4 were synthesized by the group growth on seeds method. The crystal structure was solved using a single-crystal experiment and the purity of the bulk material was proved by the Rietveld method. This borate crystallizes in the monoclinic C2/c space group with unit-cell parameters a = 7.2386 (3), b = 9.3412 (5), c = 11.1013 (4) Šand ß = 103.2240 (10)°. IR and Raman spectroscopic analyses confirmed the monoclinic structure of SmAl3(BO3)4. Under 532.1 nm excitation, luminescence spectra exhibit bands assignable to the transitions from 4G5/2 to 6H5/2, 6H7/2, 6H9/2 and 6H11/2. The similarity of the luminescence spectra of the trigonal and monoclinic polymorphs is explained by the minor role of Sm-O bond distortion and the primary role of rotational distortion of SmO6 octahedra. The smaller covalency of the Sm-O bond in alumoborates is deduced in comparison with galloborates. Calorimetric measurements did not reveal high-temperature structural phase transitions up to a temperature of 720 K.

Synthesis of Samarium OxysulfateSm2O2SO4 in the High-Temperature Oxidation Reaction and Its Structural, Thermal and Luminescent Properties.

The oxidation process of samariumoxysulfide was studied in the temperature range of 500-1000 °C. Our DTA investigation allowed for establishing the main thermodynamic (∆Hºexp = -654.6 kJ/mol) and kinetic characteristics of the process (Ea = 244 kJ/mol, A = 2 × 1010). The enthalpy value of samarium oxysulfate (ΔHºf (Sm2O2SO4(monocl)) = -2294.0 kJ/mol) formation was calculated. The calculated process enthalpy value coincides with the value determined in the experiment. It was established that samarium oxysulfate crystallizes in the monoclinic symmetry class and its crystal structure belongs to space group C2/c with unit cell parameters a = 13.7442 (2), b = 4.20178 (4) and c = 8.16711 (8)Å, ß = 107.224 (1)°, V = 450.498 (9)Å3, Z = 4. The main elements of the crystalline structure are obtained and the cation coordination environment is analyzed in detail. Vibrational spectroscopy methods confirmed the structural model adequacy. The Sm2O2SO4luminescence spectra exhibit three main bands easily assignable to the transitions from 4G5/2 state to 6H5/2, 6H7/2, and 6H9/2 multiplets.

Electronic structure of ß-RbSm(MoO4)2 and chemical bonding in molybdates.

Microcrystals of orthorhombic rubidium samarium molybdate, ß-RbSm(MoO4)2, have been fabricated by solid state synthesis at T = 450 °C, 70 h, and at T = 600 °C, 150 h. The crystal structure has been refined by the Rietveld method in space group Pbcn with cell parameters a = 5.0984(2), b = 18.9742(6) and c = 8.0449(3) Å (R(B) = 1.72%). Thermal properties of ß-RbSm(MoO4)2 were traced by DSC over the temperature range of T = 20-965 °C, and the earlier reported ß â†” α phase transition at T ∼ 860-910 °C was not verified. The electronic structure of ß-RbSm(MoO4)2 was studied by employing theoretical calculations and X-ray photoelectron spectroscopy. It has been established that the O 2p-like states contribute mainly to the upper part of the valence band and occupy the valence band maximum, whereas the Mo 4d-like states contribute mainly to the lower part of the valence band. Chemical bonding effects have been analysed from the element core level binding energy data. In addition, it was found that the luminescence spectrum of ß-RbSm(MoO4)2 is rather peculiar among the Sm(3+) containing materials. The optical refractive index dispersion in ß-RbSm(MoO4)2 was also predicted by the first-principles calculations.

Random spectrally resolved Maker fringes.

The Maker fringes technique is extended to the case of nonlinear media with one-dimensional second-order nonlinear susceptibility modulation. For broadband radiation, second harmonic intensity oscillates in both spectral and angular domains, which can be considered random spectrally resolved Maker fringes. A theoretical approach is developed for modeling the second-harmonic generation in such domain structures, and the calculations are in excellent agreement with experimental results.

Electronic structure of α-SrB4O7: experiment and theory.

The investigation of valence band structure and electronic parameters of constituent element core levels of α-SrB(4)O(7) has been carried out with x-ray photoemission spectroscopy. Optical-quality crystal α-SrB(4)O(7) has been grown by the Czochralski method. Detailed photoemission spectra of the element core levels have been recorded from the powder sample under excitation by nonmonochromatic Al Kα radiation (1486.6 eV). The band structure of α-SrB(4)O(7) has been calculated by ab initio methods and compared to XPS measurements. It has been found that the band structure of α-SrB(4)O(7) is weakly dependent on the Sr-related states.