Minimizing attosecond CEP jitter by carrier envelope phase tuning

Minimizing the CEP jitter of isolated attosecond pulses (IAP) will be important for future applications. This jitter is experimentally and theoretically investigated and can be minimized when the driving pulse is near its Fourier limit but with slightly negative chirp. Thus, understanding and characterization of the CEP jitter of IAPs is a first step towards exact control of the electric field of IAP pulses

Measuring the frequency chirp of extreme-ultraviolet free-electron laser pulses by transient absorption spectroscopy

High-intensity ultrashort pulses at extreme ultraviolet (XUV) and x-ray photon energies, delivered by state-of-the-art free-electron lasers (FELs), are revolutionizing the field of ultrafast spectroscopy. For crossing the next frontiers of research, precise, reliable and practical photonic tools for the spectro-temporal characterization of the pulses are becoming steadily more important. Here, we experimentally demonstrate a technique for the direct measurement of the frequency chirp of extreme-ultraviolet free-electron laser pulses based on fundamental nonlinear optics. It is implemented in XUV-only pump-probe transient-absorption geometry and provides in-situ information on the time-energy structure of FEL pulses. Using a rate-equation model for the time-dependent absorbance changes of an ionized neon target, we show how the frequency chirp can be directly extracted and quantified from measured data. Since the method does not rely on an additional external field, we expect a widespread implementation at FELs benefiting multiple science fields by in-situ on-target measurement and optimization of FEL-pulse properties.ISSN:2041-172

Complete reconstruction of ultra-broadband isolated attosecond pulses including partial averaging over the angular distribution

ISSN:1094-408

Extreme-ultraviolet high-order harmonic generation from few-cycle annular beams

ISSN:0146-9592ISSN:1539-479

Using a passively stable attosecond beamline for relative photoemission time delays at high XUV photon energies

ISSN:1094-408

All-XUV Pump-Probe Transient Absorption Spectroscopy of the Structural Molecular Dynamics of Di-iodomethane

In this work, we use an extreme-ultraviolet (XUV) free-electron laser (FEL) to resonantly excite the I:4d(5/2)(-sigma*) transition of a gas-phase di-iodomethane (CH2I2) target. This site-specific excitation generates a 4d core hole located at an iodine site, which leaves the molecule in a well-defined excited state. We subsequently measure the time-dependent absorption change of the molecule with the FEL probe spectrum centered on the same I: 4d resonance. Using ab initio calculations of absorption spectra of a transient isomerization pathway observed in earlier studies, our time-resolved measurements allow us to assign the timescales of the previously reported direct and indirect dissociation pathways. The presented method is thus sensitive to excited-state molecular geometries in a time-resolved manner, following a core-resonant site-specific trigger.ISSN:2160-330

Photoionization delays in xenon using single-shot referencing in the collinear back-focusing geometry

ISSN:0146-9592ISSN:1539-479

Development of a low-cost electronic stethoscope - DIY Digital Stethoscope

Auscultation while wearing PPE (especially coveralls), using traditional stethoscopes is often not feasible. While some commercially electronic stethoscopes can circumvent this problem by playing audio using headphones over/ inside PPE, the currently available ones are too costly. We plugged an electret microphone into earpiece of a stethoscope and through various audio processing algorithms improved the audio quality. We packaged these processes into an app, freely available for download from Google Play Store. Audio quality through this device is at least equivalent to the one heard through traditional stethoscopes. We are validating the device in pediatric and adult clinical setup

Photoelectron spectrometer for liquid and gas-phase attosecond spectroscopy with field-free and magnetic bottle operation modes

ISSN:0034-6748ISSN:1089-762