Direct l-doublet transitions in the 0110 state of cyanogen chloride and cyanogen bromide

Direct l doublet transitions have been observed for the 01¹0 state of the ³⁵Cl¹²C¹⁴N and ³⁷Cl¹²C¹⁴N isotopic species of cyanogen chloride and the ⁷⁹Br¹²C¹⁴N and ⁸¹Br¹²C¹⁴N isotopic species of cyanogen bromide in the frequency range 4–22 GHz. The l-doubling constants (q⁰, q¹, q²) and the asymmetry parameters (ηeQq_z) of the halogen nuclear quadrupole coupling tensors have been derived. The constants q¹ have been calculated form the vibrational force fields of Whiffen for the four cyanogen halides using the formulation of Watson. Agreement with the observed values is found to be 10% or better and for cyanogen fluoride and cyanogen chloride the isotopic shifts in q¹ are also well predicted.     

Raman spectroscopy of carbonaceous particles of environmental interest

Carbonaceous particles of environmental origin are practically insoluble, which constitutes an obstacle to many chemical physical characterization techniques. Micro‐Raman spectroscopy overcomes the sample preparation step and can be applied on the as‐received sample and even in situ, with nowadays commercially available portable Raman equipment. Multivariate statistical analysis of Raman data recorded on a variety of carbonaceous particles of different origin, through a molecular interpretation of the signal, shows that the use of Raman spectroscopy with several excitation sources can provide a useful tool for assisting the characterization of various forms of environmental carbon matter. Copyright © 2015 John Wiley & Sons, Ltd.     

A simple and flexible atom-surface potential with easy-to-handle vibrational spectrum

A highly flexible empirical potential V_p(z) suitable to describe the main features of the laterally averaged atom-surface interaction is presented and an accurate expression for the vibrational spectrum of the atom in V_p(z) is given. This establishes a simple method of inversion of the atom-surface vibrational spectra particularly suitable for levels located in the deepest 9/10 of the potential well. The present method is complementary to the one introduced by Le Roy [5].     

An a posteriori error estimator based on shifts for positive Hermitian eigenvalue problems

This work deals with an a posteriori error estimator for Hermitian positive eigenvalue problems. The proposed estimator is based on the residual and the definition of suitable shifts in the matrix spectrum. The mathematical properties (certification and sharpness) are investigated and some numerical experiments are proposed.     

Polynomials whose coefficients coincide with their zeros

In this paper we consider monic polynomials such that their coefficients coincide with their zeros. These polynomials were first introduced by S. Ulam. We combine methods of algebraic geometry and dynamical systems to prove several results. We obtain estimates on the number of Ulam polynomials of degree N. We provide additional methods to obtain algebraic identities satisfied by the zeros of Ulam polynomials, beyond the straightforward comparison of their zeros and coefficients. To address the question about the existence of orthogonal Ulam polynomial sequences, we show that the only Ulam polynomial eigenfunctions of hypergeometric type differential operators are the trivial Ulam polynomials \(\{x^N\}_{N=0}^\infty \). We propose a family of solvable N-body problems such that their stable equilibria are the zeros of certain Ulam polynomials.     

Quaternionic hyperfunctions on five-dimensional varieties in ℍ2

In this article we introduce a new notion of differential forms to describe the cohomology associated to the sheaf of regular functions in several quaternionic variables. We then use these differential forms to introduce and describe concretely a sheaf of quaternionic hyperfunctions as boundary values of regular functions in two quaternionic variables. We show how these ideas can be generalized to the case of monogenic functions in two vector variables with values in a Clifford algebra.     

Ditocopheryl Sulfides and Disulfides: Synthesis and Antioxidant Profile

Symmetrical ditocopheryl disulfides ( Toc ) ₂ S₂ and symmetrical and unsymmetrical ditocopheryl sulfides ( Toc )₂ S were simply prepared under remarkably mild conditions with complete control of the regiochemistry by using δ-, γ-, and β-tocopheryl-N-thiophthalimides ( Toc-NSPht ) as common starting materials. The roles of sulfur atom(s), H-bond and aryl ring substitution pattern on the antioxidant profile of these new compounds, which were assembled by linking together two tocopheryl units, are also discussed.