arXiv subjects

Barbara Rossi

Publications and source records attributed to Barbara Rossi.

4 recordsLinked to original sources

arXiv2025

Exploring the Growth Dynamics of Size-selected Carbon Atomic Wires with in situ UV Resonance Raman Spectroscopy

Short carbon atomic wires, the prototypes of the lacking carbon allotrope carbyne, represent the fundamental one-dimensional system and the first stage in carbon nanostructure growth, which still exhibits many open points regarding their growth and stability. We introduce an in situ UV resonance Raman approach for real-time monitoring of the growth of carbon atomic wires during pulsed laser ablation in liquid without perturbing the synthesis environment. We track single-chain species' growth dynamics, achieving size selectivity by exploiting the peculiar optoelectronic properties of carbon wires and the tunability of synchrotron radiation. We systematically explore diverse solvents, finding size- and solvent-dependent production rates linked to the solvent's C/H ratio and carbonization tendency. Carbon atomic wires' growth dynamics reveal a complex interplay between formation and degradation, leading to an equilibrium. Water, lacking in carbon atoms and reduced polyynes' solubility, yields fewer wires with rapid saturation. Organic solvents exhibit enhanced productivity and near-linear growth, attributed to additional carbon from solvent dissociation and low relative polarity. Exploring the dynamics of the saturation regime provides new insights into advancing carbon atomic wires' synthesis via PLAL. Understanding carbon atomic wires' growth dynamics can contribute to optimizing PLAL processes for nanomaterial synthesis.

physics.chem-ph↗

arXiv2025

Halogen-Terminated Carbon Atomic Wires by Laser Ablation in Halogenated Organic Solvents: Synthesis and Characterization

We report the synthesis of halogenated carbon atomic wires (halopolyynes) via pulsed laser ablation in liquid and their comprehensive Raman characterization. Using dichloromethane and dibromomethane-containing solutions, we produced polydisperse mixtures of monohalogenated (HC$_{2n}$X) and dihalogenated (XC$_{2n}$X) polyynes (X=Cl, Br; n=3-10). High-performance liquid chromatography enabled separation and analysis of these compounds, while chemical derivatization and mass spectrometry confirmed their molecular structures. A possible formation mechanism is proposed, involving carbon chain polymerization and termination by hydrogen and halogen atoms from atomized solvent molecules during the plasma phase. UV-Vis absorption and synchrotron-based UV Resonance Raman spectroscopy reveal that halogen terminations act as auxochromes through p-$\pi$ conjugation between their lone-pair electrons and the sp-carbon backbone, extending effective conjugation length. This interaction reduces bond length alternation and moderately redshifts vibronic absorption and vibrational modes. Resonance Raman spectra show selective overtone enhancement and vibrational anharmonicity consistent with carbyne-like materials. These findings expand the synthetic approaches for halogenated carbon atomic wires and establish halopolyynes as a platform for tailoring electronic and optical properties of sp-carbon wires.

physics.chem-ph↗

arXiv2025

A Machine Learning Tool to Analyse Spectroscopic Changes in High-Dimensional Data

When nanoparticles (NPs) are introduced into a biological solution, layers of biomolecules form on their surface, creating a corona. Understanding how the structure of the protein evolves into the corona is essential for evaluating the safety and toxicity of nanotechnology. However, the influence of NP properties on protein conformation is not well understood. In this study, we propose a new method that addresses this issue by analyzing multi-component spectral data using Machine Learning (ML). We apply the method to fibrinogen, a crucial protein in human blood plasma, at physiological concentrations while interacting with hydrophobic carbon or hydrophilic silicon dioxide NPs, revealing striking differences in the temperature dependence of the protein structure between the two cases. Our unsupervised ML method a) does not suffer from the challenges associated with the curse of dimensionality, and b) simultaneously handles spectral data from various sources. The method offers a quantitative analysis of protein structural changes upon adsorption and enhances the understanding of the correlation between protein structure and NP interactions, which could support the development of nanomedical tools to treat various conditions.

cond-mat.stat-mech↗

arXiv2020

Element- and enantiomer-selective visualization of ibuprofen dimer vibrations

In chemistry, biology and materials science, the ability to access interatomic interactions and their dynamical evolution has become possible with the advent of femtosecond lasers. In particular, the observation of vibrational wave packets via optical (UV-visible-IR) spectroscopies has been a major achievement as it can track the motion of nuclei within the system. However, optical spectroscopies only detect the effect of the interatomic vibrations on the global electronic surfaces. New tuneable, pulsed and polarized sources of short-wavelength radiation, such as X-Ray Free electron lasers, can overcome this limitation, allowing for chemical and, of primary importance in biochemistry, enantiomeric selectivity. This selectivity may be complemented by taking into account the chemical shifts of atoms belonging to different molecular moieties

cond-mat.soft↗