Journal of Applied Spectroscopy

In the electron energy loss spectra (EELS) of the organic europium complexes Eu3+ (BTFA)3TPPO and Eu3+(Br‐BTFA)3TPPO in a gas phase obtained on excitation by monokinetic beams of electrons of different energies in the range 12–50 eV, we have identified the bands associated with the electron transitions S 0–S 1, S 0–S 2, and S 0–S 3. The connection of these transitions with the structural groups of the complexes is established. The addition of the bromine atom to the phenyl ring of β‐diketonate leads to the rise in the relative intensity of the S 0–S 2 band. The singlet‐triplet transitions manifest themselves in the region 2.5–3.2 eV and contribute to the S 0–S 2 band of the electron energy loss spectra.

An innovative method for the simultaneous determination of Cr, Fe, Si, Mn, V, Ti, P, and S in ferrochromium was developed based on the powder compression method coupled with energy dispersive X-ray fluorescence spectrometry. The measurement conditions, current, voltage, analytical line, filter, and detector mode were optimized. The optimal sample quality, binder dosage, and tablet pressure were predicted by MINITAB software using a design of experiments that simultaneously investigated the combined effect of the different factors. The matrix and overlapping effects of the element spectrum were corrected using Epslion3 software. The results indicated that the element working curves had a good linear relationship for the selected concentration range, and the correlation coefficient of the eight elements was between 0.9912 and 0.9997. The accuracy of the proposed method was confirmed by analyzing a ferrochromium-certified reference material that had not been used in the linear regression, which ranged from 0.08 to 5.29%. The proposed technique was able to determine the Cr, Fe, Si, Mn, V, Ti, P, and S content of ferrochromium with excellent accuracy and precision, and it was superior to reported methods.

Geometric structures of phthalocyanines (MgPc, H2Pc) and their β-octaphenyl derivatives (MgPcPh8, H2PcPh8) were calculated by the DFT PBE/TZVP method; excited electronic states, by the modifi ed INDO/Sm method. An examination of the bond lengths taking into account data for porphyrazines MgTAP and H2TAP showed that the weight of the internal 16-atom macroheterocycle in the electronic structures of MgPc and MgPcPh8 increased as compared to MgTAP whereas the contribution of the 18-atom azacyclopolyene of the free bases H2Pc and H2PcPh8 decreased as compared to H2TAP. The two lowest unoccupied MOs and highest occupied MO of the examined phthalocyanines were 70% localized on the internal 16-atom macrocycle (INDO/Sm data). Filled MOs of the next lowest energy had strong mixing of the π-AOs of the 16-atom macrocycle with π-MOs of annelated benzene rings (MgPc and H2Pc) and also with π-MOs of the phenyl rings (MgPcPh8 and H2PcPh8). The Q-state energies calculated by INDO/Sm agreed with the experimental data within 200–400 cm–1. Several ππ*-transitions characterized by local excitation of the 16-atom macrocycle and electron transfer between the 16-atom ring and the benzene rings were mainly responsible for the observed broad absorption spectrum of the phthalocyanines in the range 27,000–37,000 cm–1 (Soret band). The two strongest calculated ππ*-transitions in this range agreed qualitatively with the experimental ones. However, the calculated energy was overestimated by an average of ~3000 cm–1. The calculated energy of the strongest transition for MgPcPh8 corresponded well with the experimental Soret band maximum (overestimated by only 900 cm–1).

Optical correlation methods for the analysis of gas mixtures with a quasi-periodic spectrum structure are described. The design of a device for demonstrating the possibility of using the Fabry–Perot interferometer as a correlation mask is developed. A specific example of using an interferometer in a remote methane analyzer is given.

We have shown that tunneling of weak residual localization of (n,π*) excitation on the original nitrogen atom of the azo group between its atoms causes splitting of the level for the excited state into two sublevels with different phase modulation frequencies, symmetries, and orientations of the fluorescence dipole moments relative to the axis of the azo bond. The phase modulation frequency for the lower sublevel of the state, antisymmetric to the direction of the N=N bond, is proportional to the level splitting. The diffuse nature of the emission spectrum from this sublevel is due to the high phase modulation frequency of the state.

The spectral characteristics of the emission in the 140-315 nm range from pulsed-periodic capacitive discharges in mixtures of water vapor and helium and argon are described. In the VUV the most intense bands have maxima at λ = 156.0, 180.3, and 186.0 nm, and in the region of 300–315 nm, at λ = 312.1 and 313.4 nm. The brightness of the emission from the capacitive discharge plasma is optimized with respect to the partial pressures of helium, argon, and water vapor. The electron kinetic coefficients of discharges in argon and water vapor mixtures are calculated for E/N = 1–1000 Td.