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We have synthesized L-cysteine and oleylamine stabilized CsPbBr3 perovskite quantum dots (PQDs) and coupled them with gold nanoparticles (AuNPs). The PQDs and AuNPs, as well as their hybrid nanostructures (HNS), were characterized using UV–visible (UV–vis) and photoluminescence (PL) spectroscopy. The UV–vis spectra show absorption bands of the HNS at 503 and 520 nm, attributed mainly to PQDs and AuNPs, respectively. The PQDs show a strong excitonic PL band peaked at 513 nm from PQDs. The HR-TEM results show the formation of hybrid structures between PQDs and AuNPs, which is also supported by the PL quenching of the PQDs by the coupled AuNPs. Ultrafast dynamics of the exciton and charge carriers in the HNS and pristine PQD were studied using femtosecond transient absorption. Multiexponential fitting of the dynamic data revealed the existence of shallow and deep trap states in pristine PQDs and ultrafast electron transfer from PQDs to AuNPs in the HNS. A kinetic model was proposed to account for the key dynamic processes involved and to extract the time for electron transfer from PQDs to AuNPs in the HNS, found to be ∼2 ps. Dynamic processes in pristine PQDs are largely unchanged by HNS formation with AuNPs. 

The double-slit experiment has long been pivotal in understanding matter’s wave–particle duality. A central question revolves around Born’s interpretation of wavefunction whether a single photon demonstrates a 50% probability of passing through each slit individually as particles or simultaneously traverses both as waves. Experimentally, once the photon’s path is detected, the observer effect causes its wavefunction to collapse, rendering the results inconclusive. Designing an experiment to minimize instrumental involvement during the wavefunction collapse of photons, while aiming to gain insight into its collapse mechanism, becomes necessary. We propose a revised experiment that replaces the traditional setup with two Au nanoparticles acting as observers, triggering photon collapse before spectrum collection. In single-photon scenarios, we consider two assumptions: first, the photon wavefunctions collapse into a particle and transfer energy to one of the nanoparticles exclusively, and second, the photon acts as a wave, splitting and transferring its energy to two nanoparticles simultaneously, which does not align well with Born’s interpretation of wavefunction as spatial probabilities. These two assumptions would generate distinctly different spectra. Conversely, in high-intensity experiments, both nanoparticles collectively undergo excitation, regardless of the collapse mechanism. A comparative analysis of scattering spectra under the two conditions reveals crucial insights into the genuine nature of photon collapse. We also proposed using two molecules attached to a metal nanoparticle as an alternative design. Whether affirming or refuting the observer effect, this research holds promise for resolving the theoretical debate surrounding the collapse of wavefunctions and advancing quantum computing and communication fields.