The search of compounds emitting in the near-infrared (NIR) has been accelerated owing to their use in biomedical and telecommunications applications. In this regard, nanographenes (NGs) are attractive materials adequate for integration with other technologies, which have recently demonstrated amplified spontaneous emission (ASE) and lasing across the visible spectrum. Here, the optical and ASE properties of four-zigzag edged NGs of the [m,n]peri-acenoacene family are reported, whose size is increased through conjugation extension by varying n (from 3 to 5) while keeping m = 2. Results show that such 1D conjugation extension method is more efficient in terms of shifting the photoluminescence (PL) to the infrared (PL at 710 nm in the larger compound, PP-Ar) than through 2D conjugation extension as in previously reported NGs (PL at 676 nm with the largest compound FZ3, with n = 3 and m = 4). Additionally, PP-Ar shows dual-ASE (at 726 and 787 nm), whose origin is elucidated through Raman and transient absorption spectroscopies. These compounds' potential for red and NIR lasing is demonstrated through the fabrication of distributed feedback lasers with top-layer resonators. This study paves the way towards the development of stable low-cost all-plastic NIR lasers.

Chemically synthesized zigzag-edged nanographenes (NG) have recently demonstrated great success as the active laser units in solution-processed organic distributed feedback (DFB) lasers. Here, we report the first observation of dual amplified spontaneous emission (ASE) from a large-size NG derivative (with 12 benzenoid rings) dispersed in a polystyrene film. ASE is observed simultaneously at the 685 and 739 nm wavelengths, which correspond to different transitions of the photoluminescence spectrum. Ultrafast pump-probe spectroscopy has been used to ascertain the underlying photophysical processes taking place in the films. DFB lasers, based on these materials and top-layer nanostructured polymeric resonators (i.e., one or two-dimensional surface relief gratings), have been fabricated and characterized. Lasers emitting close to either one of the two possible ASE wavelengths, or simultaneously at both of them, have been prepared by proper selection of the resonator parameters.

We demonstrate the extension of coherence between all four two-electron spin ground states of an InAs quantum dot molecule (QDM) via non-local suppression of nuclear spin fluctuations in both constituent quantum dots (QDs), while optically addressing only the upper QD transitions. Long coherence times are revealed through dark-state spectroscopy as resulting from nuclear spin locking mediated by the exchange interaction between the QDs. Lineshape analysis provides the first measurement of the quieting of the Overhauser field distribution correlating with reduced nuclear spin fluctuations.

Silver, in the form of nanostructures, is widely employed as an antimicrobial agent. The origin of the biocidal mechanism has been elucidated in the last decades, originating from silver cation release due to oxidative dissolution followed by cellular uptake of silver ions, a process that causes a severe disruption of bacterial metabolism, leading to eradication. Despite the large body of work addressing the effects of nanosilver shape/size on the antibacterial mechanism and on the (bio)physical chemistry pathways that drive bacterial eradication, little effort has been devoted to the investigation of nanostructured silver plasmon response upon interaction with bacteria. We investigate the bacteria-induced changes of the plasmonic response of silver nanoplates after exposure to the bacterial model Escherichia coli. Ultrafast pump-probe measurements indicate that the dramatic changes on particle size/shape and crystallinity, which likely stem from a bacteria-induced oxidative dissolution process, translate into a clear modification of the plasmonic response. Specifically, exposure to bacteria causes a decrease in the electron–phonon coupling time and an increase in lattice-environment coupling time, effects explained by an increase in the free electron density and amorphization of the silver particles. Coherent oscillations that are observed in pristine silver are completely damped in contaminated samples, which can be attributed again to amorphization of the nanoplates at the surface and an increase in polydispersivity of particle geometries. This study opens innovative avenues in the biophysics of bio-responsive materials, with the aim of providing reliable biophysical signatures of the interaction of plasmonic materials with complex biological environments.

Substrate engineering for steering cell growth is a wide and well‐established area of research in the field of modern biotechnology. Here we introduce a micromachining technique to pattern an inert and transparent polymer matrix blended with a photoactive polymer. We demonstrate that the obtained scaffold combines the capability to align with that to photostimulate living cells. This technology can open up new and promising applications, especially where cell alignment is required to trigger specific biological functions, e.g., generate powerful and efficient muscle contractions following an external stimulus.