Vibrationally Energy Pooling via Collisions between Asymmetric Stretching Excited CO2: A Quasi-Classical Trajectory Study on An Accurate Full-dimensional Potential Energy Surface

In low temperature plasmas, energy transfer between asymmetric stretching excited CO2 molecules can be highly efficient, which leads to further excitation (and de-excitation) of the CO2 molecules: CO2(vas) + CO2(vas)...

Auditory Inspired Convolutional Neural Networks for Ship Type Classification with Raw Hydrophone Data

Detecting and classifying ships based on radiated noise provide practical guidelines for the reduction of underwater noise footprint of shipping. In this paper, the detection and classification are implemented by auditory inspired convolutional neural networks trained from raw underwater acoustic signal. The proposed model includes three parts. The first part is performed by a multi-scale 1D time convolutional layer initialized by auditory filter banks. Signals are decomposed into frequency components by convolution operation. In the second part, the decomposed signals are converted into frequency domain by permute layer and energy pooling layer to form frequency distribution in auditory cortex. Then, 2D frequency convolutional layers are applied to discover spectro-temporal patterns, as well as preserve locality and reduce spectral variations in ship noise. In the third part, the whole model is optimized with an objective function of classification to obtain appropriate auditory filters and feature representations that are correlative with ship categories. The optimization reflects the plasticity of auditory system. Experiments on five ship types and background noise show that the proposed approach achieved an overall classification accuracy of 79.2%, which improved by 6% compared to conventional approaches. Auditory filter banks were adaptive in shape to improve accuracy of classification.

The Sommerfeld ground-wave limit for a molecule adsorbed at a surface

Using a mid-infrared emission spectrometer based on a superconducting nanowire single-photon detector, we observed the dynamics of vibrational energy pooling of carbon monoxide (CO) adsorbed at the surface of a sodium chloride (NaCl) crystal. After exciting a majority of the CO molecules to their first vibrationally excited state (v = 1), we observed infrared emission from states up to v = 27. Kinetic Monte Carlo simulations showed that vibrational energy collects in a few CO molecules at the expense of those up to eight lattice sites away by selective excitation of NaCl’s transverse phonons. The vibrating CO molecules behave like classical oscillating dipoles, losing their energy to NaCl lattice vibrations via the electromagnetic near-field. This is analogous to Sommerfeld’s description of radio transmission along Earth’s surface by ground waves.

Electronic energy pooling in organic systems: a cross-disciplinary tutorial review

Electronic energy pooling via excited state (exciton) annihilation, primarily in organic systems, is reviewed in tutorial form. Cross-disciplinary terminologies and references are used and reference is made to the historical origins of the phenomena. Applications in organic photovoltaic and electroluminescent devices are addressed. Particular attention is paid to the kinetics of the processes involved; a standard format for all systems is developed. Within the organic materials framework, all triplet–triplet, triplet–singlet, and singlet–singlet annihilation processes are discussed. Examples from gas, liquid, and solid phase systems, including both homo- and hetero-species interactions, are employed. Particular attention is given to triplet–triplet annihilation processes in which product states other than the lowest excited singlet state are formed.