Acoustic cavitation, the growth and rapid collapse of bubbles in a liquid irradiated with ultrasound, is unique source energy for driving chemical reactions sound, process known as sonochemistry. Another consequence acoustic cavitation emission light [sonoluminescence (SL)]. Spectroscopic analyses SL from single well cloud have revealed line band emission, an underlying continuum arising plasma. Application spectrometric methods pyrometry tools plasma diagnostics to relative intensities,...

The transmission electron microscope (TEM) is a powerful tool enabling the visualization of atoms with length scales smaller than Bohr radius at factor only 20 larger relativistic wavelength 2.5 pm 200 keV. ability to visualize matter these in TEM largely due efforts made correcting for imperfections lens systems which introduce aberrations and ultimately limit achievable spatial resolution. In addition progress increasing resolution, has become an all-in-one characterization tool. Indeed,...

Abstract Precise manipulation and control of coherent lattice oscillations via nanostructuring phonon-wave interference has the potential to significantly impact a broad array technologies research areas. Resolving dynamics individual phonons in defect-laden materials presents an enormous challenge, however, owing interdependent nanoscale ultrafast spatiotemporal scales. Here we report direct, real-space imaging emergence evolution acoustic at defects crystalline WSe 2 Ge. Via bright-field...

Acoustic cavitation (the growth, oscillation, and rapid collapse of bubbles in a liquid) occurs all liquids irradiated with sufficient intensity sound or ultrasound. The such creates local heating provides unique source energy for driving chemical reactions. In addition to sonochemical bond scission formation, also induces light emission many liquids. This phenomenon sonoluminescence (SL) has captured the imagination researchers since it was first observed 85 years ago. SL direct probe...

In this Perspective, we provide an overview of the field ultrafast electron microscopy (UEM). We begin by briefly discussing emergence methods for probing structural dynamics and information that can be obtained. Distinctions are drawn between two main types probes femtosecond (fs) dynamics—fast electrons X-ray photons—and emphasis is placed on how nature charged particles exploited in electron-based experiments. Following this, describe versatility enabled ease with which trajectories...

Advances in the imaging of biological structures with transmission electron microscopy continue to reveal information at nanometer length scale and below. The images obtained are static, i.e., time-averaged over seconds, weak contrast is usually enhanced through sophisticated specimen preparation techniques and/or improvements optics methodologies. Here we report application technique photon-induced near-field (PINEM) specimens femtosecond (fs) temporal resolution. In PINEM, structure...

We use bright-field imaging in an ultrafast electron microscope to spatiotemporally map the evolution of photoexcited coherent strain waves a single, micrometer-size flake MoS2. Following situ femtosecond photoexcitation, we observe individual wave trains emerge from discrete nanoscale morphological features and propagate in-plane along specific vectors at approximately speed sound (7 nm/ps). Over span several hundred picoseconds, 50 GHz (20 ps periods) are observed undergo phonon–phonon...

Despite the development of a myriad mitigation methods, radiation damage continues to be major limiting factor in transmission electron microscopy. Intriguing results have been reported using pulsed-laser driven and chopped beams for modulated dose delivery, but underlying relationships effects remain unclear. Indeed, delivering precisely timed single-electron packets specimen has yet systematically explored, no direct comparisons conventional methods within common parameter space made....

The average pressure inside a sonoluminescing bubble in sulfuric acid has been determined by two independent techniques: (1) plasma diagnostics applied to Ar atom emission lines, and (2) light scattering measurements of radius vs time. For dimly luminescing bubbles, both methods yield intracavity pressures approximately 1500 bar. Upon stronger acoustic driving the bubble, sonoluminescence intensity increases 10,000-fold, spectral lines are no longer resolved, time internal > 3700...

Electrodeposited Fe and Fe-Au nanowires were studied for potential as MRI contrast agents, especially T2-weighted imaging. Transverse relaxivities up to r2 = 77.1 mM Fe-1 s-1 (at 1.5 T) achieved when coated with thiol carboxylic acid functionalized poly(ethyleneglycol). T2-Weighted images (9 verified successful contrast.

The large elastic strains that can be sustained by transition metal dichalcogenides (TMDs), and the sensitivity of electronic properties to strain, make these materials attractive targets for tunable optoelectronic devices. Defects have also been shown influence optical properties, characteristics are especially important understand applications requiring high precision sensitivity. Importantly, photoexcitation TMDs is known generate transient strain effects but associated intralayer...

Emission lines from transitions between high-energy states of noble-gas atoms (Ne, Ar, Kr, and Xe) ions (Ar(+), Kr(+), Xe(+)) formed excited during single-bubble cavitation in sulfuric acid are reported. The responsible for these emission range 8.3 eV (for to 37.1 Ar(+)) above the respective ground states. Observation allows identification intracavity species light emission; populated energy levels indicate plasma generated is comprised highly energetic particles.

Variations in sonoluminescence (SL) from an acoustically driven but rapidly translating bubble solutions of sulfuric acid with alkali-metal salts coincide variations translational dynamics. At low acoustic pressures, emission Ar excited states is observed and the motion smooth elliptical. elevated SL intensity decreases, atoms observed, becomes increasingly erratic frequent abrupt changes direction. These results provide a direct experimental link between single multibubble point toward...

The function of many nano- and microscale systems is revealed when they are visualized in both space time. Here, we report our first observation, using four-dimensional (4D) electron microscopy, the nanomechanical motions cantilevers. From observed oscillations nanometer displacements as a time, for free-standing beams, able to measure frequency modes motion determine Young's elastic modulus force energy stored during optomechanical expansions. cantilever triggered by molecular charge...

We report correlative crystallographic and morphological studies of defect-dependent phonon dynamics in single flakes 1T-TaS2 2H-WSe2 using selected-area diffraction bright-field imaging an ultrafast electron microscope. In both materials, we observe in-plane speed-of-sound acoustic-phonon wave trains, the which (i.e., emergence, propagation, interference) are strongly dependent upon discrete interfacial features (e.g., vacuum/crystal crystal/crystal interfaces). TaS2, cross-propagating...

We report real-space, time-resolved imaging of coherently excited acoustic phonon modes in plasmonic nanoparticles via femtosecond electron with an ultrafast microscope. The particles studied were cetyl trimethylammonium bromide stabilized Au nanorods (40 × 120 nm), and the particular specimen configurations for which photoinduced vibrational visualized consisted a single, isolated nanocrystal cluster four irregularly arranged randomly oriented particles, all supported on amorphous Si3N4...

Ultrafast electron microscopes with thermionic guns and LaB6 sources can be operated in both the nanosecond, single-shot femtosecond, single-electron modes. This has been demonstrated conventional Wehnelt electrodes absent any applied bias. Here, by conducting simulations using General Particle Tracer code, we define electron-gun parameter space within which various modes may optimized. The properties of interest include collection efficiency, temporal energy spreads, effects laser-pulse...