Anharmonic, Temperature, and Matrix Effects on the Molecular Structure and Vibrational Frequencies of Lanthanide Trihalides LnX3 (Ln = La, Lu; X = F, Cl)

Application of a low-cost water level circuit for an accurate pulse detection of a tipping-bucket rain gauge as an alternative method for reed switch sensors

This paper introduces a data acquisition mechanism working on similar functionality to that of conventional tipping-bucket rain gauge (TBRG) but unaffected from magnetic and electromagnetic interferences. Unlike the common reed switch application, the mechanism of this study only uses a two-wire water level sensor for tip detection. Specifically, a different method of detecting the tipping count of the rain gauge through a switching type scheme is introduced without using the conventional magnetic detection concept. The designed electronic two-wire TBRG has so many features, with its low-cost and its resistance to metallic or electromagnetic interference the most important. The sensor design makes the circuit assembly applicable to any cylindrical or cube-type rain gauge sizes. The only important thing to properly mount is the placement of the wire contacts. A bottom-feed design was implemented in this study. The RI approximation resulted in relative errors - 5%, - 3.27%, and - 4.73 from the sample flow rates 11 mL/min, 32 mL/min, and 57 mL/min respectively. Underestimations of 0.09 mL (approximately 0-mm water depth), 2.48 mL (0.45 mm), and 5.65 mL (1.03 mm) were recorded from calculating the tips made without the calibrating algorithms from the 10-mL, 40-mL, and 70-mL samples respectively. Although it proves its measuring ability through its slight underestimation results, the hardware and its corresponding mechanism have proven reliable in accordance with its functionality. The measuring performance of the device proved that it has the capability to work in similar to the conventional TBRG.

Modelling the matrix shift on the vibrational frequency of ThO by DFT-D3 calculations

Benchmark calculations with a goal to find dispersion-corrected DFT-D3 methods suitable for a reliable estimation of matrix shifts on the vibrational frequency were carried out on the ThO molecule in three rare gas (Rg = Ne, Ar, and Kr) matrices. The matrices were modelled by the explicit approach, in which a single and a double shell of Rg atoms around ThO was considered. The selection of exchange-correlation functionals was based on test calculations on triatomic ThO⋯Rg models. The B3LYP, PBE0, CAM-B3LYP, and LC-ωPBE functionals were found to be the best suited for the estimation of matrix shifts. The single shell of Rg's around ThO accounted for a major part of the shifts; the addition of a second Rg shell resulted only in a minor improvement. Continuum solvation models considerably overestimated the effect of Rg matrices both when the whole matrix was treated by the model and when the first shell was treated explicitly and the rest with a continuum solvation model.

Investigation of Praseodymium Fluorides: A Combined Matrix-Isolation and Quantum-Chemical Study

The chemistry of the lanthanides is mostly dominated by compounds in the oxidation state +III. Only few compounds of Ce, Pr, and Tb are known with the metal in the +IV oxidation state. Removal of the last f-electron on praseodymium +IV would lead to a closed-shell system with formal oxidation state V. In this work we investigated the stability of the PrF5 molecule by theory and matrix-isolation techniques through the reaction of laser-ablated praseodymium atoms with fluorine in excess of neon, argon, krypton, or neat fluorine. Besides the known PrF3 molecule, unreported IR bands for PrF4 could be observed, and there is evidence for the formation of PrF and PrF2 but not for the formation of PrF5.

Dehydrogenation of Methanol by Vanadium Oxide and Hydroxide Cluster Cations in the Gas Phase

Bare vanadium oxide and hydroxide cluster cations, V(m)O(n)+ and V(m)O(n-1) (OH)+ (m = 1-4, n = 1-10), generated by electrospray ionization, were investigated with respect to their reactivity toward methanol using mass spectrometric techniques. Several reaction channels were observed, such as abstraction of a hydrogen atom, a methyl radical, or a hydroxymethyl radical, elimination of methane, and adduct formation. Moreover, dehydrogenation of methanol to generate formaldehyde was found to occur via four different pathways. Formaldehyde was released as a free molecule either upon transfer of two hydrogen atoms to the cluster or upon transfer of an oxygen atom from the cluster to the neutral alcohol concomitant with elimination of water. Further, formaldehyde was attached to V(m)O(n)+ upon loss of H2 or neutral water to produce the cation V(m)O(n)(OCH(2))+ or V(m)O(n-1) (OCH(2))+, respectively. A reactivity screening revealed that only high-valent vanadium oxide clusters are reactive with respect to H2 uptake, oxygen transfer, and elimination of H2O, whereas smaller and low-valent cluster cations are capable of dehydrogenating methanol via elimination of H2. For comparison, the reactivity of methanol with the corresponding hydroxide cluster ions, V(m)O(n-1) (OH)+, was studied also, for which dominant pathways lead to both condensation and association products, i.e., generation of the ions V(m)O(n-1) (OCH(3))+ and V(m)O(n-1) (OH)(CH(3)OH)+, respectively.

Quasilinear Molecule par Excellence, SrCl2: Structure from High-Temperature Gas-Phase Electron Diffraction and Quantum-Chemical Calculations—Computed Structures of SrCl2⋅Argon Complexes

The molecular geometry of strontium dichloride has been determined by high-temperature electron diffraction (ED) and computational techniques. The computation at the MP2 level of theory yields a shallow bending potential with a barrier of about 0.1 kcal mol(-1) at the linear configuration. The experimentally determined thermal average Sr--Cl bond length, r(g), is 2.625+/-0.010 A and the bond angle, angle-spherical(a), is 142.4+/-4.0 degrees . There is excellent agreement between the equilibrium bond lengths estimated from the experimental data, 2.607+/-0.013 A, and computed at different levels of theory and basis sets, 2.605+/-0.006 A. Based on anharmonic analyses of the symmetric and asymmetric stretching as well as the bending motions of the molecule, we estimated the thermal average structure from the computation for the temperature of the ED experiment. In order to emulate the effect of the matrix environment on the measured vibrational frequencies, a series of complexes with argon atoms, SrCl(2)Ar(n) (n=1-7), with different geometrical arrangements were calculated. The complexes with six or seven argon atoms approximate the interaction best and the computed frequencies of these molecules are closer to the experimental ones than those computed for the free SrCl(2) molecule.