Traveling a long way past the junction Diodes are central components of modern electronic circuits. They essentially consist two semiconductors sandwiched together, with one deficient in electrons (p), other enriched (n). Najafi et al. used ultrafast electron microscopy to study dynamics silicon diode on time scale trillionths second. discovered that when light excites diode's charge carriers, those carriers migrate much farther p-n than standard models would imply. The authors explain...

We have studied, experimentally and theoretically, the ionization probability of carbonyl sulfide (OCS) molecules in intense linearly polarized 800-nm laser pulses as a function angle between molecular axis polarization. Experimentally, are exposed to two with relative time delay. The first, weaker pulse induces nuclear rotational wave packet within each molecule such that ensemble exhibits preferential alignment laboratory frame at specific times. second, stronger ionization, variation...

We study, experimentally and theoretically, the ionization probability of singly halogenated methane molecules, CH3Cl CH3Br, in intense linearly polarized 800 nm laser pulses as a function angle between molecular axis polarization. Experimentally, molecules are exposed to two with relative time delay. The first, weaker pulse induces nuclear rotational wave packet within which then ionized by second, stronger pulse. angle-dependent yields extracted from fits measured delay-dependent signal...

The NSF NeXUS user facility is designed to enable direct observation of electron motion with attosecond femtosecond time resolution, angstrom spatial and element-specific spectral resolution. will level the scientific playing field by providing researchers across disciplines access most advanced characterization tools available worldwide for studying ultrafast dynamics in molecules materials.

We introduce a simple and practical method to create ultrashort intense optical vortices for applications involving high-intensity lasers. Our utilizes femtosecond laser pulses etch grating lines into laser-quality gold mirrors. These holographically encode an vortex. derive mathematical equations each individual line be etched, any desired (integer) topological charge. investigate the smoothness of etched grooves. show that they are smooth enough produce with intensity is only few percent...

We report on the photoionization and photofragmentation of benzene (C(6)H(6)) monohalobenzenes C(6)H(5)-X (X = F, Cl, Br, I) under intense-field, single-molecule conditions. focus 50-fs, 804-nm pulses from a Ti:sapphire laser source, record ion mass spectra as function intensity in range ∼10(13) W/cm(2) to ∼10(15) W/cm(2). count ions that were created central, most intense part focal area; other regions are rejected. For all targets, stable parent (C(6)H(5)X(+)) observed. Our data is...

We present molecular-frame measurements of the recombination dipole matrix element (RDME) in CO2, N2O, and carbonyl sulfide (OCS) molecules using high-harmonic spectroscopy. Both amplitudes phases RDMEs exhibit clear imprints a two-center interference minimum, which moves energy with molecular alignment angle relative to laser polarization. find that whereas dependence this minimum is consistent geometry CO2 it behaves very differently OCS; particular, phase shift accompanies changes sign...

We report on the ultrafast photoionization of pyridine, pyridazine, pyrimidine, and pyrazine. These four molecules represent a systematic series perturbations into structure benzene ring which explores substitution C–H entity with nitrogen atom, creating heterocyclic structure. Data are recorded under intense-field, single-molecule conditions. The pulses (50 fs, 800 nm) focused molecular vapor, ion mass spectra for intensities ∼1013 W/cm2 to ∼1015 W/cm2. measure yields in absence focal...

High-harmonic generation was used to probe the spectral intensity and phase of recombination-dipole matrix element methyl chloride (CH3Cl), revealing a Cooper minimum (CM) analogous 3p CM previously reported in argon. The structure altered response group delay (GD) emitted harmonics, revealed only through careful removal all additional contributors GD. In characterizing GD dispersion, also known as “attochirp” we additionally present most complete validation date commonly strong-field...

We demonstrate high-harmonic spectroscopy in many-electron molecules using time-dependent density-functional theory. show that a weak attosecond-pulse-train ionization seed is properly synchronized with the strong driving mid-infrared laser field can produce experimentally relevant generation (HHG) signals, from which we extract both spectral amplitude and target-specific phase (group delay). also further processing of HHG signal be used to achieve molecular-frame resolution, i.e., resolve...

We perform ab initio calculations of high-harmonic spectroscopy (HHS) two-center interference phenomena in oriented carbon-dichalcogen molecules, using time-dependent density functional theory (TDDFT). show that by resolving the harmonic response into contributions from individual Kohn-Sham orbitals, we can extract target-specific characteristics for both spectral amplitude and phase. also discuss this extraction is predicated on a careful analysis normalization spectrum. Finally, present...

Intense-field stability of photoionization and fragmentation are compared for aniline (C₆H₅–NH₂) nitrobenzene (C₆H₅–NO₂), with amine <italic>vs.</italic> nitro substitutions explored.

We present molecular-frame high-harmonic spectroscopic measurements of the spectral intensity and group delay carbon dioxide. Using four different driving wavelengths a range intensities at each wavelength for generation, we observe well-characterized minimum in harmonic emission that exhibits both dependence. dependence wavelength, classify as due to either structural two-center interference or dynamic multichannel interference, consistent with previous literature. By additionally measuring...

We report experimental values of the group velocity dispersion (GVD) water and methanol at 800 nm. find GVD800water= (25.71 ± 0.5) fs 2 mm−1 GVD800methanol=(33.56 ±0.5) fs2 mm−1. These were measured by sending 50 fs, nm pulses with various amounts chirp through a glass cell filled solution fluorescein in these solvents recording production visible light from side using commercial digital camera. This simple setup also gives quantitative information on duration our lets us check independently...

We present quantitative simulations of the focal volume effect. Intensity distributions in detection volumes with two- and three-dimensional spatial resolution are calculated. Results include an analysis translations these focus along direction laser propagation as well discussion varying sizes spatially resolved volumes. find that less than half 1/e full-width beam waist Rayleigh length offer optimal compromise maintaining intensity without sacrificing peak intensity.

We report on the fragmentation of ionized pyridine (C(5)H(5)N) molecules by focused 50 fs, 800 nm laser pulses. Such ionization produces several metastable ionic states that fragment within field-free drift region a reflectron-type time flight mass spectrometer, with one particular dissociation being leading process. Because is no longer dependent in simple way ion, decay manifested as an unfocused peak spectrum appears at not corresponding to integer mass. A previously-developed method used...

Using 50-fs, 800-nm pulses, we study the intense-field ionization and fragmentation of monohalobenzenes C6H5-X (X=F, Cl, Br, I) heterocyclics azabenzene C5H5N (pyridine) three diazabenzenes C4H4N2 (pyridazine, pyrimidine, pyrazine). Avoiding focal intensity averaging find indications resonance-enhanced MPI. In propensity for increases increasing Z: fluorobenzene yields predominantly C6H5Fn+, while iodobenzene atomic ions with charges up to I8+. We ascribe this heavy-atom effect: large charge...

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