Mid-IR laser action in the H3 Rydberg molecule and some possible astrophysical implications

Mid-IR lasing has been observed in supersonic plasmas and assigned to d to p transitions in tri-atomic hydrogen Rydberg states. Possible astrophysical implications are discussed

Dynamics of Micropollutant Adsorption to Polystyrene Surfaces Probed by Angle-Resolved Second Harmonic Scattering

Angle-resolved second harmonic scattering is used to probe the adsorption dynamics of aqueous cationic and anionic dye molecules onto polystyrene surfaces. The adsorptions of malachite green to negatively charged polystyrene and naphthol yellow S to positively charged polystyrene are both highly favorable, with Î"GAds values of -10.9 ± 0.2 and -10.27 ± 0.09 kcal/mol, respectively. A competitive displacement methodology was employed to obtain values for the adsorption free energies of various smaller neutral organic molecules, including the important micropollutant ascorbic acid, caffeine, and pentoxifylline. For charged adsorbers, electrostatic interactions appear to significantly contribute to adsorption behavior. However, electrostatic repulsion does not necessarily deter the adsorption of molecules with large uncharged moieties (e.g., surfactants). In these cases, the mechanism of adsorption is dominated by van der Waals interactions, with the surface charge playing a relatively minor role

Terahertz VRT spectroscopy of the water hexamer-d<inf>12</inf> prism: Dramatic enhancement of bifurcation tunneling upon librational excitation

Using diode laser vibration-rotation-tunneling spectroscopy near 15 Thz (500 cm−1), we have measured and assigned 142 transitions to three a-type librational subbands of the water hexamer-d12 prism. These subbands reveal dramatically enhanced (ca. 1000×) tunneling splittings relative to the ground state. This enhancement is in agreement with that observed for the water dimer, trimer, and pentamer in this same frequency region. The water prism tunneling motion has been predicted to potentially describe the motions of water in interfacial and confined environments; hence, the results presented here indicate that excitation of librational vibrations has a significant impact on the hydrogen bond dynamics in these macroscopic environments.</jats:p

Mid-IR laser action in the H 3 Rydberg molecule and some possible astrophysical implications

Mid-IR lasing has been observed in supersonic plasmas and assigned to d to p transitions in tri-atomic hydrogen Rydberg states. Possible astrophysical implications are discussed

Terahertz spectroscopy of water clusters

We seek to develop a 'universal predictive model' for water in all its forms, such that any question about water could be answered by a suitable computer calculation. We this by combining highly detailed measurements of water clusters made by terahertz laser spectroscopy(a technology that our group pioneered two decades ago) with the best available computer calculations. We have published many papers on this subject, addressing clusters ranging from water dimer to hexamer[1]

Spectroscopy and modeling of aqueous interfaces

The development of deep-UV second-harmonic generation spectroscopy (SHG) for measuring the strong charge transfer to solvent (CTTS) transitions characteristic of all stable aqueous anions has provided a powerful new probe of water interfaces. By employing suitable models, quantitative thermodynamic results have been obtained for a number of fundamental electrolytes, which are generally in good agreement with theoretical calculations. Details of the experiments and models are described and salient results supporting a novel mechanism for the selective adsorption of ions to the air/water interface are reviewed