General Selection Rule in the Inelastic Neutron Scattering Spectroscopy of a Diatomic Molecule Confined Inside a Near-Spherical Nanocavity

Knowledge of the relevant selection rules is crucial for the accurate interpretation of experimental spectra in general. There has been a consensus for a long time that the incoherent inelastic neutron scattering (INS) spectroscopy of the vibrations of discrete molecular compunds is free from any selection rules. We contradict this widely held view by presenting an analytical derivation of the general selection rule for the INS spectroscopy of a hydrogen molecule inside a near-spherical nanocavity. It defines all forbidden transitions, originating in a range of initial translation-rotation (TR) states, ground and excited, of the caged para- and ortho-H₂, as well as HD, that are unobservable in the INS spectra. These predictions are amenable to experimental verification. In addition, we demonstrate that the general selection rule applies to the INS spectroscopy of any diatomic molecule in a nanocavity with near-spherical symmetry, which exhibits strong TR coupling. Its existence strongly suggests that similar selection rules apply to the INS spectra of other molecular and supramolecular systems, and need to be identified

Relationship between ecosystem coordination and health assessment.

<p>Relationship between ecosystem coordination and health assessment.</p

Trends of ecosystem health index in the Pearl River Estuary.

<p>(a) the ecosystem variability indexes from 1980 to 2005, (b) the ecosystem variability indexes from 2005 to 2009, (c) the ecosystem health index from 1980 to 2009.</p

Map of Pearl River Estuary.

<p>Map of Pearl River Estuary.</p

Contributions of ecosystem structure and services to coordination.

<p>Contributions of ecosystem structure and services to coordination.</p