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This study focuses on the recognition and isolation of fullerenes, which are crucial for further exploration of their physical and chemical properties. Our goal is to investigate the potential recognition of the D5h–C70 fullerene using crown-shaped metal compositions through density functional theory calculations. We assess the effectiveness of fullerene C70 recognition by studying the binding energy. Additionally, various analyses were conducted, including natural bond order charge analysis and reduced density gradient analysis, to understand the interaction mechanism between the host and guest molecules. These investigations provide valuable insights into the nature of the interaction and the stability of the host–guest system. To facilitate the release of the fullerene guest molecule, the vis–NIR spectra were simulated for the host–guest structures. This analysis offers guidance on the specific wavelengths that can be utilized to release the fullerene guest from the host–guest structures. Overall, this work proposes a new strategy for the effective recognition of various fullerene molecules and their subsequent release from host–guest systems. These findings could potentially be applied in assemblies involving fullerenes, advancing their practical applications. [ABSTRACT FROM AUTHOR]

This study focuses on the recognition and isolation of fullerenes, which are crucial for further exploration of their physical and chemical properties. Our goal is to investigate the potential recognition of the D5h–C70 fullerene using crown-shaped metal compositions through density functional theory calculations. We assess the effectiveness of fullerene C70 recognition by studying the binding energy. Additionally, various analyses were conducted, including natural bond order charge analysis and reduced density gradient analysis, to understand the interaction mechanism between the host and guest molecules. These investigations provide valuable insights into the nature of the interaction and the stability of the host–guest system. To facilitate the release of the fullerene guest molecule, the vis–NIR spectra were simulated for the host–guest structures. This analysis offers guidance on the specific wavelengths that can be utilized to release the fullerene guest from the host–guest structures. Overall, this work proposes a new strategy for the effective recognition of various fullerene molecules and their subsequent release from host–guest systems. These findings could potentially be applied in assemblies involving fullerenes, advancing their practical applications. [ABSTRACT FROM AUTHOR]

We report the results of linked theoretical and experimental studies of external infrared reflectivity by a Langmuir monolayer. The new feature in our analysis is the inclusion of the influence of the factor group splitting, arising from the presence of two molecules in the unit cell of a close packed two-dimensional monolayer lattice (CS phase), on the polarized reflection spectra of the monolayer. Our experimental study of the polarized reflection spectra of water supported Langmuir monolayers of tetracosanoic acid [H(CH2)23COOH] provide the first measurements of the factor group splittings of the CH2 symmetric and antisymmetric stretch vibrations in the CS phase of a monolayer. The existence of a nonzero factor group splitting is direct evidence for the presence of herringbonelike hydrocarbon chain packing in a two-dimensional crystalline phase of the monolayer. We also report values for the collective tilt angle in the tetracosanoic acid monolayer, as a function of surface area per molecule. The collective tilt angles for the unstrained I phase and the U phase of the tetracosanoic acid monolayer found in this work agree with those obtained from grazing incidence x-ray diffraction studies. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We report the results of a grazing incidence x-ray diffraction study of monolayers of F(CF2)11COOH and F(CF2)10CH2COOH on water at several temperatures. It is found that in both monolayers the amphiphile molecules have a very small collective tilt angle (relative to the normal to the surface). For the temperature range studied (∼4–30 °C) the data for both monolayers indicate the existence of only a first-order transition between an ordered condensed phase and a disordered dilute phase; there is no evidence, in this temperature range, for the existence of a continuous tilt transition such as has been observed in monolayers of arachidic acid. The experimental data suggest that the critical point for the transition observed is at a lower temperature for a monolayer of F(CF2)11COOH than for a monolayer of F(CF2)10CH2COOH. [ABSTRACT FROM AUTHOR]

We have used an optical-infrared double resonance technique to probe the nature of the eigenstates prepared by 4νOH vibrational overtone excitation in hydrogen peroxide. A visible dye laser excites the 4←0 OH stretch transition and an optical parametric oscillator promotes the molecules above the dissociation threshold by a ΔvOH=2 transition from the 4νOH level. Fixing the overtone excitation laser wavelength and scanning the wavelength of the infrared photon while monitoring the dissociation fragments by laser-induced fluorescence generates an infrared predissociation spectrum of the vibrationally excited molecule that contains information about vibrational state mixing at the 4νOH level. This spectrum indicates that the zeroth-order state that gives oscillator strength to the 4←0 OH stretch transition (i.e., the 4νOH bright state) is almost entirely comprised of a single vibrational eigenstate. Since the bright state is predominantly an OH stretch, the vibrational eigenstate prepared by 4νOH vibrational overtone excitation is well localized on the OH bond. This localization allows us to perform sequential local mode–local mode excitation of the two equivalent OH oscillators in HOOH. [ABSTRACT FROM AUTHOR]

Infrared predissociation spectroscopy of nitric acid subsequent to vibrational overtone excitation reveals vibrational state mixing of the highly excited levels and probes the character of the coupled dark states. A visible dye laser excites the 4←0 or 5←0 OH stretch transition and an optical parametric oscillator promotes the molecules above the dissociation threshold by a ΔvOH=1 transition from the excited level. Scanning the optical parametric oscillator frequency while monitoring the predissociation products via laser-induced florescence produces an infrared spectrum of the excited molecules. Although the 4νOH vibrational overtone band consists of a single clean rotational contour that falls directly on a Birge–Sponer plot, the infrared transitions from this level indicate that the zeroth-order bright state is extensively mixed. On the average, the zeroth-order bright state is only a minor component of the eigenstates at this energy. The largest collective contribution is from zeroth-order states that have zero quanta of OH stretch. [ABSTRACT FROM AUTHOR]