Vibrational and optical spectroscopies integrated with environmental transmission electron microscopy.

Here, we present a measurement platform for collecting multiple types of spectroscopy data during high-resolution environmental transmission electron microscopy observations of dynamic processes. Such coupled measurements are made possible by a broadband, high-efficiency, free-space optical system. The critical element of the system is a parabolic mirror, inserted using an independent hollow rod and placed below the sample holder which can focus a light on the sample and/or collect the optical response. We demonstrate the versatility of this optical setup by using it to combine in situ atomic-scale electron microscopy observations with Raman spectroscopy. The Raman data is also used to measure the local temperature of the observed sample area. Other applications include, but are not limited to: cathodo- and photoluminescence spectroscopy, and use of the laser as a local, high-rate heating source.

A pilot study on behavioral and cognitive effects of Cognitive Stimulation Training based on 3R Mental Stimulation. The Treviso Dementia (TREDEM) Study.

OBJECTIVES: Cognitive Stimulation (CS) trainings are non-pharmacological treatments widely used in dementia care. 3R Mental Stimulation is a particular type of CS, which consists of sequential association of ROT, Reminiscence and Remotivation during the same session. This pilot study sought to investigate whether CS, based on 3R program, could benefit cognitive functions, autonomy and behavioral disorders. METHOD: 3R-CS treatment was applied to 36 patients, which are part of the "TREDEM" study sample, and their caregivers. All patients received a multidimensional assessment consisting of a socio-demographic, clinical and neuropsychological data collection. RESULTS: After CS treatment a significant improvement was detected in cognition and autonomy in basic activities of daily living. Caregiver distress was decreased. Behavioral disturbances were reduced even when considering a potential confounding factor such as treatment with anticholinesterase or NMDA receptor antagonist drugs. CONCLUSION: The findings demonstrated that 3R-CS can benefit cognitive functions and level of autonomy in the basic activities of daily living and also it can reduce behavioral disorders and caregiver's distress.

Ultralocal modification of surface plasmons properties in silver nanocubes.

The plasmonic properties of individual subwavelength-sized silver nanocubes are mapped with nanometric spatial resolution by means of electron energy-loss spectroscopy in a scanning transmission electron microscope. Three main features with different energies and spatial behavior (two peaked at the corners, one on the edges) are identified and related to previous measurements on ensemble or individual nanoparticles. The highly subwavelength mapping of the energy position and intensity of the excitations shows that the surface plasmon modes, localized at specific areas of the particles, for example, the corners or the edges, are modified by their size, the presence of a substrate, and the very local environment. Helped by discrete dipole approximation numerical simulations, we discuss how local modifications of the environment affect the global modes of the particles. In particular, we show both experimentally and theoretically that absorption resonances at different corners of the same nanocube are largely independent of each other in energy and intensity. Our findings provide a better understanding of the spatial coherence of the surface plasmons in nanoparticles but also give useful insights about their roles in the nanoparticle sensing properties.

Nanometer scale spectral imaging of quantum emitters in nanowires and its correlation to their atomically resolved structure.

We report the spectral imaging in the UV to visible range with nanometer scale resolution of closely packed GaN/AlN quantum disks in individual nanowires using an improved custom-made cathodoluminescence system. We demonstrate the possibility to measure full spectral features of individual quantum emitters as small as 1 nm and separated from each other by only a few nanometers and the ability to correlate their optical properties to their size, measured with atomic resolution. The direct correlation between the quantum disk size and emission wavelength provides evidence of the quantum confined Stark effect leading to an emission below the bulk GaN band gap for disks thicker than 2.6 nm. With the help of simulations, we show that the internal electric field in the studied quantum disks is smaller than what is expected in the quantum well case. We show evidence of a clear dispersion of the emission wavelengths of different quantum disks of identical size but different positions along the wire. This dispersion is systematically correlated to a change of the diameter of the AlN shell coating the wire and is thus attributed to the related strain variations along the wire. The present work opens the way both to fundamental studies of quantum confinement in closely packed quantum emitters and to characterizations of optoelectronic devices presenting carrier localization on the nanometer scale.

Zeptomol detection through controlled ultrasensitive surface-enhanced Raman scattering.

SERS permits identifying the nature of molecules in extremely low concentrations, but it is hindered by poor enhancement or low reproducibility. We demonstrate controllable approximately 10(10) signal amplification reaching the zeptomol detection limit for a nonresonant molecule by sandwiching the analyte between the tips of star-shaped gold nanoparticles and a planar gold surface using a simple synthetic procedure. This unprecedented control over light-intensity amplification opens a new avenue toward high-yield, fully reproducible, SERS-based, zeptomol detection and holds promise for nonlinear optics applications at the single-particle level.