Dimers or trimers? A characterization of the halogen bonded complexes of CFX (X=I or Br) with dimethyl ether and acetone in cryosolutions.

Acetone molecules dissolved in liquid krypton are inclined to self-associate into dimers. This behavior affects its use as a prototype Lewis base in studies of weak intermolecular interactions. In this study infrared spectra of mixed solutions of dimethyl ether and CFX and of acetone and CFX (with X=I or Br) dissolved in liquid argon and liquid krypton are recorded at constant temperature.

Self-Associating Behavior of Acetone in Liquid Krypton.

Acetone molecules are inclined to self-associate through dipole-dipole interactions because of their large dipole moment. Infrared spectroscopy of compounds dissolved in liquid noble gases supported by high level ab initio calculations allows investigating the self-associating behavior and determining the thermodynamical properties. In this study, infrared spectra of various concentrations of acetone dissolved in liquid krypton are recorded at constant temperature.

Exploring the limits of cryospectroscopy: Least-squares based approaches for analyzing the self-association of HCl.

To rationalize the concentration dependent behavior observed for a large spectral data set of HCl recorded in liquid argon, least-squares based numerical methods are developed and validated. In these methods, for each wavenumber a polynomial is used to mimic the relation between monomer concentrations and measured absorbances. Least-squares fitting of higher degree polynomials tends to overfit and thus leads to compensation effects where a contribution due to one species is compensated for by a negative contribution of another.