A comprehensive study of the vibrational predissociation dynamics of the HCl dimer is reported. The predissociation lifetimes for three H–Cl stretch vibrationally excited states of (H35Cl)2 have been measured. Companion measurements for the H35Cl•H37Cl complex have also been made. These lifetimes range from 16(2) to 46(5) ns, lifetimes that are more than 106 times longer than the H–Cl stretch vibrational period. The correlated HCl(v′=0,j′)+HCl(v″=0,j″) fragment rotational state distributions have also been determined. These show a predominant dynamical bias that favors the production of j′,j″ pairs that maximize the rotational energy of the fragments and minimize their translational energy. The j′,j″ distribution is well described by a simple energy gap model of the dissociation. The results suggest a complex, for which there are substantial excursions from the equilibrium geometry, dissociation from a wide range of geometries, weak coupling of the H–Cl stretch vibrations to the dissociation coordinate, and a blurring of the distinction between hydrogen bonded and free HCl moieties. These results are consistent with theoretical studies of the HCl dimer potential energy surface.

Adhesion force measurements are used to determine potential dependence of the force of adhesion between a Si3N4 cantilever and an Au surface in basic solution. At both positive and negative potentials, the force curve is dominated by van der Waals contributions, indicating that there is little specific interaction between the tip and the sample. However, at intermediate potentials (between 0.4 and 0.6 V vs SHE) the tip−sample interaction is dominated by an adhesive component, the magnitude of which is approximately 2 kJ/mol; this corresponds to the expected strength of a hydrogen bond between O- groups on the tip and AuOH on the surface.

Rising cases of COVID-19 caused St. John’s University to transition to an online educational model in the spring 2020 semester. As a result, an in-person Cooperative Learning advanced general chemistry laboratory course was transitioned into an online/remote Cooperative Learning experience. Cooperative Learning in the general chemistry laboratory has been shown to reinforce authentic foundational scientific practices. The Cooperative Learning methodological approach was extended to incorporate alternative data collection sources such as virtual experiments, but otherwise unchanged. This communication discusses the benefits of adopting such an approach and critically evaluates our results. Analysis of our findings shows that while simulated experiments supplemented with a sufficient framework can be used to meet laboratory learning outcomes, they do not fully replace the hands-on laboratory experience.

The ν1 vibrational predissociation lifetime of (HCN)2 determined from upperstate microwaveinfrared doubleresonance measurements J. Chem. Phys. 99, 8559 (1993); 10.1063/1.465579Study of collisional effects on band shapes of the ν1/2ν2 Fermi dyad in CO2 gas with stimulated Raman spectroscopy. I. Rotational and vibrational relaxation in the 2ν2 band J. Chem. Phys. 93, 2176 (1990); 10.1063/1.459049The effect of vibrational state mixing on the predissociation lifetime of ν1 excited OC-HF

Adhesion force measurements are used to determine the potential dependence of the force of adhesion between a Si3N4 cantilever and a Au(111) surface modified by the underpotential deposition (upd) of Bi or Cu in acid solution or by oxide formation. The measured work of adhesion is near zero for most of the potential region examined in Bi upd but rises after the formation of a full Bi monolayer. The work of adhesion is high at positive potentials for Cu upd but then decreases as the Cu partial and full monolayers are formed. The work of adhesion is low in the oxide region on Au(111) but rises following the sulfate disordering transition at 1.1 V vs NHE. These results are interpreted in terms of the degree of solvent order on the electrode surface.