Van der Waals Complexes

Laser-induced fluorescence excitation spectra of MeRg (Me = Zn, Cd; Rg = He, Ne, Ar, Kr, Xe) complexes were recorded using the D 1 R þ 0 X 1 R þ 0 free bound transition. The complexes were produced in their ground state in a free-jet expansion beam and excited with a dye-laser beam directly to the excited state. Analysis of free bound unstructured profiles provided a shape of the repulsive part of the D 1 R þ 0-state potentials. Valence ab initio calculations of the ZnRg and CdRg ground-and excited-state potentials and electronic transition dipole moments for the studied transition were performed, taking scalar relativistic and spin-orbit effects into account. Results of the calculations show regularities and correlations in the repulsive branches and bound wells of the X 1 R þ 0-and D 1 R þ 0-state potentials as well as provide information on the bonding character in both electronic energy states. The trends were compared with available experimental results for ZnRg and CdRg as well as for MgRg and HgRg.

Spectroscopic results are presented concerning the 2CH excitation around 1.5 mm in van der Waals complexes of acetylene (C 2 H 2) with Ar, Kr, N 2 , CO 2 , N 2 O and C 2 H 2. Many are reviewed from the literature, with some updates. Previously unpublished results are also presented, concerning the mechanism of formation of C 2 H 2-Ar in the supersonic jet, the assignment of new spectral structures in C 2 H 2-N 2 O, and the first observation of 2CH excitation in C 2 H 2-Ne, C 2 H 2-H 2 O, C 2 H 2-D 2 O and (C 2 H 2) n. Lifetimes of these 2CH vibrationally excited dimers are discussed.

A topological atom is a quantum object with a well-defined intra-atomic energy, which includes kinetic energy, Coulomb energy, and exchange energy. In the context of intermolecular interactions, this intra-atomic energy is calculated from supermolecular wave functions, by using the topological partitioning. This partitioning is parameter-free and invokes only the electron density to obtain the topological atoms. In this work, no perturbation theory is used; instead, a single wave function describes the behavior of all van der Waals complexes studied. As the monomers approach each other, frontier atoms deform, which can be monitored through a change in their shape and volume. Here we show that the corresponding atomic deformation energy is very well described by an exponential function, which matches the well-known Buckingham repulsive potential. Moreover, we recover a combination rule that enables the interatomic repulsion energy between topological atoms A and B to be expressed as ...

Reactions of atomic oxygen with complexes containing HCI are investigated and the OH product state distributions are compared to those observed for the corresponding reactions of HCI monomers. In previous studies of reactions of oC P) with HCI and hydrocarbon complexes, rotationally colder OH product state distributions were observed, when compared to the corresponding reactions of monomers. In contrast, we find that reactions of O(1 D) with HCI clusters yield OH rotational distributions that are unaffected by the incorporation of HCI into a van der Waals complex. Quasiclassical trajectories are run on collisions of oxygen with HCI and Ar" •HCI at 1 eV collision energies to investigate the differences in the dynamics of the OeD) and oC P) reactions. It is found that when the van der Waals complex is longer lived than the collision complex, rotational and vibrational cooling are observed. In contrast, when the dissociation of the van der Waals complex is prompt, compared to the collision complex lifetime, the effects of complex formation on the internal energy of the OH product become negligible.

Laser-induced fluorescence excitation spectra of MeRg (Me = Zn, Cd; Rg = He, Ne, Ar, Kr, Xe) complexes were recorded using the D 1 R þ 0 X 1 R þ 0 free bound transition. The complexes were produced in their ground state in a free-jet expansion beam and excited with a dye-laser beam directly to the excited state. Analysis of free bound unstructured profiles provided a shape of the repulsive part of the D 1 R þ 0-state potentials. Valence ab initio calculations of the ZnRg and CdRg ground-and excited-state potentials and electronic transition dipole moments for the studied transition were performed, taking scalar relativistic and spin-orbit effects into account. Results of the calculations show regularities and correlations in the repulsive branches and bound wells of the X 1 R þ 0-and D 1 R þ 0-state potentials as well as provide information on the bonding character in both electronic energy states. The trends were compared with available experimental results for ZnRg and CdRg as well as for MgRg and HgRg.

Infrared nanoimaging is used to detect a type of surface collective mode in a representative van der Waals crystal. van der Waals heterostructures assembled from atomically thin crystalline layers of diverse two-dimensional solids are emerging as a new paradigm in the physics of materials. Our results are likely to hold true in other polar van der Waals crystals and may lead to new functionalities. SURESH KUMAR.S 2-D structures are products of natural evolution in biomodels based on cytoplasmic nanoconfinement of matter,with properties that differ drastically from bulk-state nature and dynamics. Polaritonic effects reported here are likely generic to other polar molecules of peptide side chains of hydrophobic protein folded interior structures because these materials might often show optical phonon modes. There are reports of resonant mechanisms for vibrational energy transfers in air-water like interfacial hydration close to ordered protein surfaces in vapourphase domains.The propagation of optical range phonon modes could be probably described by applying non-linear Schrodinger type equations,with minimum dissipation losses,due to potential polaritonic effects in a photonic environment in cellular systems. Biothermal states would facilitate strong coulombic coupling of polar molecules in peptide side chain moities of vapour phase protein interiors based on anomalous dipole moments induced on hydrophobic surfaces in photonic hydration in such nanconfigurations of cytoplasmic cavities .This is potentially facilitated in an emf environment,with highly structured interfacial hydration close to protein surfaces and highly ordered molecular structures.The slow relaxation of water molecular dipoles and dielctric sensitivities would possibly enable implementation of quantum logic gate functioanlity for coherent measurements of coupled polarisation states as qubit systems.The protein structures in such vapour phase interiors of folded biomacromolecular structures with high molecular order have been studied by applying a dry Hamiltonian to model interfacial hydration. The molecular order would correlate probably with an IR overtone in phonon signal mode,as observed in analogous polymeric structures in the condensed phase.The optical range phonons have long propagation overcoming biosystem dissipation based on biothermal energy metabolism,probably based on polaritonic phenomena coupled to photonic field environment,and its QED effects in photonic hydration.The vapour phase nanocavity confinement would facilitate this for photon -phonon coupling and exchange of field energies for large scale dynamical order due to long range signalling.The quantum information is possibly measured coherently and communicated non linearly based on polaritonic phenomena

The size and position of tissue during vertebrate body plan development may rely on the cooperation of mechanisms that act globally and locally. [Also see Report by Dias et al.] SURESH KUMAR.S During vertebrate embryogenesis, the body plan is established through the organization of blocks of tissue (somites) that form along either side of the neural tube, the precursor to the adult spinal cord;a regularly arranged pattern of somites arises from the patternless presomitic mesoderm.It is possible that there is communication of signal from the neural tube and its interfacial hydration structure,based on nanoconfined water layer and molecular coherence,analogous to pseudoglassy phase.This would simulate supercooled liquid,which provides for phonon modes,with non-linear anomalous peaks,with an IR overtone. In a condensed phase,similar to polymeric models,biopolymers can potentially give rise to highly ordered molecular structures,that probably reveal underlying quantum like resonances for long range signal propagation ,and its large scale dynamical order and behaviour in the biosystem.The biopolymeric macromolecular structures and surfaces have ultrafast transmission of vibrational energy signals based on local confinement in helical nanostructures of polymeric models corresponding to macromolecular protein biostructures.The peak anomalies of vibrational phonon modes for energy transfer makes possible non linear resonances in pseudoglassy models,with analogies to supercooled liquid systems.The macromolecular structures and surfaces together with interfacial hydration in such nanoconfinement would possibly form a heterogenous sytem which is finetuned in cytoplasmic nanospaces based on hydrophilicity and hydrophobicity,for dynamical order in large scale system behaviour.The enthalpic and entropic effects are probably balanced in such nanoconfined cytoplasmic structures and configurations for macromolecular and supramolecular assemblies depicting molecular information functions and quantum like resonances for energy efficiency and functional optimisation,leading to large scale behaviour with long range order.The neural tube hydration structure in association with adjacent interfaces of nanoconfined molecular layer of water and macromolecular structures and surfaces provide patterns of non-linear resonances for large scale order based on signal propagation with anomalous peaks for vibrational energy transfer modes across the interfaces. The local confinement in nanohelical structures of biomacromolecules further facilitate this for long range signal propagation,with resonant modes enabled by interfacial hydration structure,and molecular order.

The influence of presence of counter ions and π-complexation with benzene on the bonding and
magnetic properties of Al4
2, the most studied all-metal cluster, is studied here. It is shown that
complexation by either counter ions or benzene decreases the delocalization index between
Al atoms and the magnitude of bond magnetizability, that is a Quantum Theory of Atoms in
Molecules, QTAIM, -based magnetic index of aromaticity. Benzene forms two types of π-complexes
with the Al4 framework; CH–π (T-shaped) complexes and parallel π–π stacking (PPS) complexes.
It is shown that variation in the p-charge of the Al4 framework affects the relative stability of the
T-shaped/PPS complexes. Free Al4
2 forms a stable T-shaped anion–π complex with benzene but
in the presence of cations, formation of PPS complexes is more favourable, energetically. It is
suggested that this property could be used for designing molecular switches and tuneable anion
sensors.