Theoretical study of highly excited Σ and Π states of NaLi and experimental observation of the interacting 5Σ and 6Σ states

Theoretical multireference configuration interaction (MRDCI) calculations on the excited ¹Σ⁺ and ¹Π states of NaLi are presented. They improve the results of a previous study by two of the present authors, resolve some differences with other theoretical results and lead to overall good agreement with experimental observations. To extend the experimental data base of electronic states in NaLi, a previously unknown ¹Σ⁺ state is investigated by polarisation labelling spectroscopy. Comparison with accompanying and previous theoretical calculations leads to a conclusion that the observed system consists of two band systems switching smoothly from one adiabatic state to the other and allows assignment of the bands as 5¹Σ⁺ ← X¹Σ⁺ in the lower energy part and to 6¹Σ⁺ ← X¹Σ⁺ for higher energies.     

Energies and radial couplings for the Σ and Σ states of the NaHe quasimolecule

We present the energies and radial couplings for the five ¹Σ and four ³Σ states of lowest energy of the NaHe⁺ quasimolecule, with a precision which is sufficient to treat Na/He⁺ collisions. The characteristics of energies and couplings are studied in detail with the aid of qualitative orbital and state-correlation diagrams.     

Reactions of N2(A3Σ)

N₂(A³Σ), the lowest electronically excited state of N₂, has a long and distinguished history due to its role in nitrogen discharges and the nitrogen afterglow. Recently, the production of N₂(A) via photolysis and chemiluminescent reactions has been newly explored, and new facets of its reactivity have been uncovered. N₂(A) is unusual, in that its deactivation probability in collision with small molecules spans many orders of magnitude, and is frequently strongly dependent on the vibrational content of N₂(A). This behavior and the observed product channels can be understood in terms of a simple model for the energy transfer process. Brief comparison with reactions of related species is made.     

On the eigenvalues of a 3 by 3 non-Hermitian Hamiltonian

In this paper, we are concerned with a 3 × 3 complex matrix Jacobi (tri-diagonal matrix) arised from a non-Hermitian discrete quantum system. Necessary and sufficient conditions for reality of the eigenvalues of the matrix in question are established.     

Hydration of C3a in the presence of CaCO3

The hydration of C₃A with and without CaCO₃ was studied. The techniques used were X-ray diffraction, thermogravimetry, differential thermogravimetry and calorimetry.In the presence of CaCO₃, the hydration of C₃A is accelerated. The hexagonal hydrates are formed first. They react with CaCO₃ to form calcium carboaluminate hydrate. This reaction blocks formation of the cubic hydrate. The latter appears when CaCO₃ is completely consumed.     

Matrix-isolated NCl. Radiative rates for b Π→a Δ, b Σ→X Σ and a Δ→X Σ in solid argon

Radiative rates for the b→a, b→X, and a→X transitions in NCl have been determined in solid argon. The rates - corrected for the refractive index - are 520, 260, and 0.27 s⁻¹. The b→X and a→X rates are in good agreement with calculated rates, whereas the b→a rate is enhanced by five orders of magnitude in the matrix.     

First observation of the 3Π and 4Π states of NaLi molecule

Two previously unknown electronic states of NaLi molecule have been observed by polarisation labelling spectroscopy in the energy region of 29 900–34 100 cm⁻¹ above the bottom of the molecular ground state potential well. The states are identified as 3¹Π(Na(3d) + Li(2s)) and 4¹Π(Na(4p) + Li(2s)). The Dunham coefficients are derived for both states and the potential energy curves constructed by the Rydberg–Klein–Rees method.     

Intermodulated fluorescence spectroscopy of caf AΠ-XΠ

The A ²Π-X²∑⁺ 0-0 transition of CaF has been examined by the technique of intermodulated fluorescence spectroscopy (“Lamb dip”). The hyperfine structure due to ¹⁹F and the spin-rotation fine structure of the X ²∑⁺ state was determined. Parameter values of b = 104.0 (9) MHz, c = 58(6) MHz and γ = 38.6(2) MHz were found for v = 0 of X²∑⁺     

Spectroscopic constants and molecular properties of A3Σu+, B3Πg,W3Δu,and B′3Σu− electronic states of the N2 molecule

The potential energy curves (PECs) of A³Σ, B³Π_g, W³Δ_u, and B^′3Σ electronic states of the N₂ molecule have been studied for internuclear separations from 0.05 to 2.0 nm using the full valence complete active space self‐consistent‐field method followed by the highly accurate valence internally contracted multireference configuration interaction (MRCI) approach in conjunction with the correlation‐consistent basis sets. Effects on the PECs by the core–valence correlation and relativistic corrections are taken into account. The way to consider the relativistic correction is to use the second‐order Douglas‐Kroll Hamiltonian approximation. The core–valence correlation correction is made with the cc‐pCV5Z basis set. And the relativistic correction is performed at the level of cc‐pV5Z basis set. To obtain more reliable results, the PECs determined by the MRCI calculations are also corrected for size‐extensivity errors by the Davidson modification (MRCI+Q). These PECs are extrapolated to the complete basis set limit. The spectroscopic parameters of ¹⁴N₂, ¹⁴N¹⁵N, and ¹⁵N₂ isotopologs have been evaluated and compared with those reported in the literature. Excellent agreement has been found between the present results and the Rydberg‐Klein‐Rees (RKR) data. With the PECs obtained by the MRCI+Q/CV+DK+56 calculations, the first 30 vibrational states for three species are computed for each electronic state. And for each electronic state of each species, the vibrational level G(ν), inertial rotation constant B_ν, and centrifugal distortion constant D_ν have been determined, which agree well with the RKR data. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012     

Fiber spinning behavior of a 3-hydroxybutyrate/3-hydroxyhexanoate copolymer

The fiber spinning behavior of a poly(3-hydroxyalkanoate) (PHA) copolymer resin containing 11.3 mol% hexanoate copolymer (H11) was studied to determine its usefulness in fiber based applications, such as nonwovens. Monocomponent fibers were spun initially, but it was found they would not solidify in the spinline. Bicomponent (sheath/core) fibers were melt spun using a H11 core and a polylactic acid (PLA), as well as a polyethylene succinate (PES) sheath. The spinning results showed that H11 levels up to 30wt% could be incorporated with stable spinning. The incorporation of H11 was found to be limited due to the slow crystallization kinetics of the H11 in the spinline. The neat and bicomoponent fibers were found to have tensile strengths similar to polypropylene. The PES based fiber compositions were found to have elongation-at-break values similar to PP. Neat H11 copolymer fibers were found to be readily biodegradable at 25°C under aerobic conditions.     

Tetramerization of 3-methyl-cyclopropene-3-carbonitrile: a novel CN-alder-ene reaction

At elevated temperatures 3-methyl-cyclopropene-3-carbonitrile 1 was found to tetramerize giving compound 2 (3-methyl-2,3-bis(2-t-methyl-2-c-cyanocyclopropyl)-1-(2-t-methyl-2-c,3-c-dicyanocyclopropyl)-cyclopropene) in good yields. This is the first example of Alder-ene type oligomerization of a 3,3-disubstituted cyclopropene. On the basis of the product geometry and stereoselective character of the reaction, a mechanism of formation of 2 involving CN-Alder-ene reaction was proposed. DFT modeling of the mechanism has shown that the CN-Alder-ene reaction is possible as a stepwise process involving a biradical intermediate.     

3H-Indol-3-ols by a novel ring contraction

Treatment of α-hydroxy-α-phenyl-o-toluidide with phosphorus tribromide afforded a series of 4H-3,1-benzoxazines. These last, when reacted with potassium amide in liquid ammonia, ring contracted to 2,3-disubstituted 3H-indol-3-ols. The scope of this rearrangement was examined. The indolols on treatment with hot base were found to rearrange to indoxyls. Several of these as well as their N-alkylation products are described.     

Synthesis and Crystal Structure of a New 3-Amino-3-deoxy Derivative from 3-Keto-D-xylose

The title compound 2 was synthesized by the reaction of 3-keto-D-xylose with O-C6H4NH2NH2 and characterized by IR, NMR and HRMS, and its crystal structure was determined by X-ray diffraction analysis. The crystal is of orthorhombic system （C21H22N2O5, Mr = 382.41）, space group P2 1 2 1 2 1 with α = 10.140（2）, b = 10.802（2）, c = 17.840（4） A, β = 90°, V = 1954.1（7）A^3, Z = 4, Dc = 1.300 g/cm^3, F（000） = 808, μ = 0.094 mm^-1, the final R = 0.0354 and wR = 0.0514 for 1924 observed reflections （I 〉 2σ（I））. One intermolecular and one intramolecular hydrogen bonds were found. The absolute configuration of this molecule was confirmed by comparison with that of the original material.