Nelssom Fernandez Cunha

We demonstrate that pulsed laser annealing induces plasmonic gold nanoparticles in ZnO thin films, monitored in real-time via pulse-by-pulse spectroscopy. Initially embedded gold nanoparticles (smaller than 5 nm) in sputtered ZnO films were annealed using 532 nm pulses from a Q-switched Nd:YAG laser while monitoring transmission spectra in situ. A plasmonic resonance dip emerged after ~100 pulses in the 530–550 nm region, progressively deepening with continued exposure. Remarkably, different incident energies converged to a thermodynamically stable optical state centered near 555 nm, indicating robust nanoparticle configurations. After several hundred laser shots, the process stabilized, producing larger nanoparticles (40–200 nm diameter) with significant surface protrusion. SEM analysis confirmed substantial gold nanoparticle growth. Theoretical modeling supports these observations, correlating spectral evolution with particle size and embedding depth. The protruding gold nanoparticles can be functionalized to detect specific biomolecules, offering significant advantages for biosensing applications. This approach offers superior spatial selectivity and real-time process monitoring compared to conventional thermal annealing, with potential for optimizing uniform nanoparticle distributions with pronounced plasmonic resonances for biosensing applications.

We demonstrate that pulsed laser annealing induces the formation of plasmonic gold nanoparticles in ZnO thin films, with the process monitored in real-time through pulse-by-pulse spectroscopy. Gold nanoparticles (smaller than 5 nm) were initially embedded in sputtered ZnO films on fused silica substrates. ZnO was selected as the matrix material for its inherent antimicrobial properties, which complement the plas-monic sensing functionality. Using 532 nm pulses with energies of 20 mJ, and a diame-ter of 2 mm from a Q-switched Nd:YAG laser, we induced annealing while simultane-ously monitoring transmission spectra via in-situ broadband spectroscopy. A plas-monic resonance dip emerged after approximately 100 laser pulses in the 530–550 nm region, progressively deepening and broadening with continued exposure. The process stabilized after roughly 800 shots, producing larger nanoparticles (40–200 nm diame-ter) with a significant fraction protruding from the ZnO surface. SEM analysis con-firmed substantial particle coarsening. Theoretical modeling supports these observa-tions, correlating spectral evolution with particle size and embedding depth. The pro-truding gold nanoparticles can be functionalized to detect specific biomolecules, of-fering significant advantages for biosensing applications. This approach offers the po-tential to optimize more uniform nanoparticle distributions with pronounced plas-monic resonances while providing superior spatial selectivity and real-time process monitoring compared to conventional thermal annealing.

This work explores the self-assembly and optical properties of a novel chiral, aromatic-rich Boc-Phe-Phe dipeptide derivative functionalized with a benzothiazole bicyclic ring, which forms supramolecular structures. Leveraging the well-known self-assembling capabilities of diphenylalanine dipeptides, this modified derivative introduces a heterocyclic benzothiazole unit that significantly enhances the fluorescence of the resulting nanostructures. The derivative’s rich aromatic character drives the formation of supramolecular structures through self-organization mechanisms influenced by quantum confinement. By adjusting the solvent system, the nanostructures exhibit tunable morphologies, ranging from nanospheres to nanobelts. Furthermore, the nonlinear optical properties of these self-assembled structures are studied and an estimated deff of ~0.9 pm/V is obtained, which is comparable to that reported for the highly aromatic triphenylalanine peptide.

A test station setup devised to measure the emission characteristics and beam propagation parameters of a light detection and ranging (LiDAR) system is presented. The main blocks of the station to measure the accessible emission, wavelength peak and FWHM, pulse duration, pulse repetition rate, horizontal and vertical angular resolution, field of view, beam propagation factor M², beam waist size, waist location, and divergence are described. The performance of this test station was demonstrated using a commercial spinning LiDAR, a Velodyne VLP-16, which successfully enables these measurements for a laser beam with a wavelength of 913 nm.