Classification of Land-Water Continuum Habitats Using Exclusively Airborne Topobathymetric Lidar Green Waveforms and Infrared Intensity Point Clouds

Coastal areas host highly valuable ecosystems that are increasingly exposed to the threats of global and local changes. Monitoring their evolution at a high temporal and spatial scale is therefore crucial and mostly possible through remote sensing. This article demonstrates the relevance of topobathymetric lidar data for coastal and estuarine habitat mapping by classifying bispectral data to produce 3D maps of 21 land and sea covers at very high resolution. Green lidar full waveforms are processed to retrieve tailored features corresponding to the signature of those habitats. These features, along with infrared intensities and elevations, are used as predictors for random forest classifications, and their respective contribution to the accuracy of the results is assessed. We find that green waveform features, infrared intensities, and elevations are complimentary and yield the best classification results when used in combination. With this configuration, a classification accuracy of 90.5% is achieved for the segmentation of our dual-wavelength lidar dataset. Eventually, we produce an original mapping of a coastal site under the form of a point cloud, paving the way for 3D classification and management of land and sea covers.

Unavoidable Failure of Point Charge Descriptions of Electronic Density Changes for Out-of-Plane Distortions

<div>Population analyses based on point charge approximations accurately estimating the equilibrium dipole moment will systematically fail when predicting infrared intensities of out-of-plane vibrations of planar molecules, whereas models based on both charges and dipoles will always succeed. It is not a matter of how the model is devised, but on its number of degrees of freedom. Population analyses based on point charges are very limited in terms of the amount of meaningful chemical information they provide, whereas models employing both atomic charges and atomic dipoles should be preferred for molecular distortions. A good model should be able to correctly describe not only static, equilibrium structures but also distorted geometries in order to correctly assess information from vibrating molecules. The limitations of point charge models also hold for distortions much larger than those encountered vibrationally.</div>

Unavoidable Failure of Point Charge Descriptions of Electronic Density Changes for Out-of-Plane Distortions

<div>Population analyses based on point charge approximations accurately estimating the equilibrium dipole moment will systematically fail when predicting infrared intensities of out-of-plane vibrations of planar molecules, whereas models based on both charges and dipoles will always succeed. It is not a matter of how the model is devised, but on its number of degrees of freedom. Population analyses based on point charges are very limited in terms of the amount of meaningful chemical information they provide, whereas models employing both atomic charges and atomic dipoles should be preferred for molecular distortions. A good model should be able to correctly describe not only static, equilibrium structures but also distorted geometries in order to correctly assess information from vibrating molecules. The limitations of point charge models also hold for distortions much larger than those encountered vibrationally.</div>

Synthesis, Crystal Structure, Vibrational Study and DFT Computation of Barium Dihydrogenomonophosphate Ba(H2PO4)2

The single crystal of barium dihydrogenomonophosphate, Ba(H2PO4)2 was prepared by the direct method. This compound exists in two forms: one orthorhombic, the other triclinic. In this work, we are interested in the triclinic form from the vibrational and crystalline side too. X-ray crystallography showed that this compound crystallizes in the triclinic centrosymmetric with space group P-1 (Z=2) with a = 6.9917(5)Å,b = 7.1929(5)Å,c = 7.9667(9)Å,α = 104.517(8)°,β = 95.918(7)° and γ = 109.459(6). The structure was solved from 3444 independent reflections with R = 0.0198 with wR= 0.0633.The bands observed in the infrared and Raman spectra of Ba(H2PO4)2 are assigned based on the literature results and the theoretical group analyses carried out in the group of factors Ci. The optimal molecular geometry, harmonic vibrational frequencies, infrared intensities, and Raman scattering activities were calculated using density functional theory (DFT/B3LYP) methods with the LanL2DZ basis set. The HOMO-LUMO properties and geometries of this compound have been determined and discussed. The computational structural parameters are generally in agreement with the experimental investigations. The theoretical infrared and Raman spectra for the title compound have been constructed.

Vibrational exciton delocalization precludes the use of infrared intensities as proxies for surfactant accumulation on aqueous surfaces

Surface-sensitive vibrational spectroscopy is a common tool for measuring molecular organization and intermolecular interactions at interfaces. Peak intensity ratios are typically used to extract molecular information from one-dimensional spectra but...