Adi Natan

Standoff detection of trace amounts of solids by nonlinear Raman spectroscopy using shaped femtosecond pulses

We demonstrate a single-beam, standoff (>10m) detection and identification of various materials including minute amounts of explosives under ambient light conditions. This is obtained by multiplex coherent anti-Stokes Raman scattering spectroscopy (CARS) using a single femtosecond phase-shaped laser pulse. We exploit the strong nonresonant background for amplification of the backscattered resonant CARS signals by employing a homodyne detection scheme. The simple and highly sensitive spectroscopic technique has a potential for hazardous materials standoff detection applications.

Ultrafast X-ray Auger probing of photoexcited molecular dynamics

Molecules can efficiently and selectively convert light energy into other degrees of freedom. Disentangling the underlying ultrafast motion of electrons and nuclei of the photoexcited molecule presents a challenge to current spectroscopic approaches. Here we explore the photoexcited dynamics of molecules by an interaction with an ultrafast X-ray pulse creating a highly localized core hole that decays via Auger emission. We discover that the Auger spectrum as a function of photoexcitation--X-ray-probe delay contains valuable information about the nuclear and electronic degrees of freedom from an element-specific point of view. For the nucleobase thymine, the oxygen Auger spectrum shifts towards high kinetic energies, resulting from a particular C-O bond stretch in the ππ* photoexcited state. A subsequent shift of the Auger spectrum towards lower kinetic energies displays the electronic relaxation of the initial photoexcited state within 200 fs. Ab-initio simulations reinforce our interpretation and indicate an electronic decay to the nπ* state.

Quantum state measurements using multipixel photon detectors

The characterization and conditional preparation of multiphoton quantum states require the use of photonnumber resolving detectors. We study the use of detectors based on multiple avalanche photodiode pixels in this context. We develop a general model that provides the positive operator value measures for these detectors. The model incorporates the effect of cross talk between pixels which is unique to these devices. We validate the model by measuring coherent-state photon-number distributions and reconstructing them with high precision. Finally, we evaluate the suitability of such detectors for quantum state tomography and entanglement-based quantum state preparation, highlighting the effects of dark counts and cross talk between pixels.

Standoff detection via single-beam spectral notch filtered pulses

We demonstrate single-beam coherent anti-Stokes Raman spectroscopy (CARS), for detecting and identifying traces of solids, including minute amounts of explosives, from a standoff distance (>50 m) using intense femtosecond pulses. Until now, single-beam CARS methods relied on pulse-shapers in order to obtain vibrational spectra. Here we present a simple and easy-to-implement detection scheme, using a commercially available notch filter, that does not require the use of a pulse-shaper.

Quantum control of photodissociation by manipulation of bond softening

We present a method to control photodissociation by manipulating the bond-softening mechanism occurring in strong shaped laser fields, namely by varying the chirp sign and magnitude of an ultrashort laser pulse. Manipulation of bond softening is experimentally demonstrated for strong-field (

Observation of Quantum Interferences via Light Induced Conical Intersections in Diatomic Molecules

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Strongly aligned gas-phase molecules at free-electron lasers.

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Probing ultrafast ππ* / nπ* internal conversion in organic chromophores via K-edge resonant absorption

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Probing electron delays in above-threshold ionization

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Spatio-temporal coherent control of atomic systems: weak to strong field transition and breaking of symmetry in 2D maps

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