The photoabsorption and photoionization spectra of molecular nitrogen, N2 , near the first ionisation threshold display numerous intense resonances that have not been satisfactorily assigned to date. Principal among these is a pair of broad resonances between 126,200 and 126,600 cm -1 commonly referred to as the "cathedral" bands. Here, we present new double-resonance photoionization spectra in this region recorded via the a '' 1 Sigma g+,v '=0 intermediate state as well as new high-resolution, vacuum-ultraviolet photoabsorption spectra of 14 N 2 , 14 N 15 N, and 15 N 2 to provide additional insight into the assignment of these features. Progress towards a fully consistent interpretation of the existing data on these bands is discussed, and a route towards a comprehensive description of the N2 absorption spectrum up to the B 2 Sigma u+ state of N 2+ is proposed.
The understanding of flow characteristics and heat transfer process through micro- and nanochannels has gained significant importance due to their effective thermal performance for MEMS-based applications. Due to the limitations of Computational Fluid Dynamics at higher Knudsen Number, Molecular Dynamics simulations act as a more suitable approach for capturing nanoscale flow. Therefore, this study is conducted to investigate heat dissipation from a sub-microchannel heat sink using a novel multi-scale approach. Seven scaled-down geometries are modelled, with the smallest channel length and height reaching 0.2 and 0.1 & micro;m, respectively, which demonstrate how scaling down the channel influences dimensionless parameters; i.e. Reynolds Number, Knudsen Number and Nusselt Number. The characteristics of velocity and temperature profiles are also analysed, revealing vortex formation at sub-micro scale, which cannot be fully captured by conventional CFD due to the absence of interatomic interactions. The findings reveal a notable difference between MD and CFD outcomes, highlighting that flow and heat transfer properties are highly attributed to slip effects, temperature gradient, wall-fluid interactions and surface wettability. Thus, these findings contribute to a better understanding of flow and heat transfer mechanisms at sub-micron scale and support the development of coupled MD-CFD frameworks for accurate analysis.
The contamination of environmental systems by Pb(II), Cd(II) and Hg(II) poses serious ecological and health risks due to their high toxicity and bioaccumulation. In this study, we investigate the structural, electronic and thermodynamic properties of aliphatic and aromatic dithiocarbamate complexes of these heavy metals using density functional theory (DFT) as implemented in Gaussian 16, followed by a detailed analysis of their adsorption onto Fe2O3 and Fe3O4 surfaces. Calculated adsorption energies reveal three consistent and predictive trends: Fe3O4 outperforms Fe2O3 for five of the six complexes studied, owing to mixed Fe2+/Fe3+ redox centers that facilitate superior electronic adaptability; adsorption strength follows a metal dependent hierarchy of Pb(II) > Cd(II) > Hg(II) for aliphatic complexes on Fe3O4; and aliphatic ligands consistently outperform aromatic counterparts by reducing steric hindrance. Strong adsorption correlates with substantial dipole moment increases, yet the Hg aliphatic complex on Fe3O4 presents a striking exception, demonstrating that linear Hg coordination geometry overrides electronic softness and renders dipole moment alone an insufficient predictor of binding strength. Thus, high polarisability, weak acidity, and geometric compatibility collectively govern adsorption efficacy. This work establishes that Fe3O4 functionalised with aliphatic Pb(II) or Cd(II) complexes provides the strongest performance, whereas Hg(II) removal requires alternative surface designs.
In this work, we investigate the vibrational properties and thermodynamic behaviour of a linear molecule subjected to a pseudoharmonic potential in the background spacetime of a global monopole. By formulating the Schr & ouml;dinger equation using the Laplace-Beltrami operator and solving the resulting radial equation with the Asymptotic Iteration Method (AIM), closed-form expressions for the energy eigenvalues are obtained. The presence of the global monopole, characterised by the parameter alpha, modifies the effective centrifugal term and rescales the vibrational spectrum, leading to shifts in both the energy spacing and the ground-state energy. Using the derived spectrum, the vibrational partition function is constructed, from which key thermodynamic quantities - including the internal energy, specific heat capacity, Helmholtz free energy, and entropy -are analytically evaluated. Our results show that the topological defect significantly influences the thermal properties of the molecule, with stronger monopole effects enhancing the population of excited vibrational states and increasing the vibrational entropy. In the limit alpha -> 1 , the standard flat-space results are recovered. These findings highlight the role of spacetime topology in molecular spectroscopy and extend the study of molecular systems in curved backgrounds to the thermodynamic regime.
