Lev Kazak

ORCID: 0000-0003-3404-1698
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About
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Research Areas
  • Laser-Matter Interactions and Applications
  • Laser-induced spectroscopy and plasma
  • High-pressure geophysics and materials
  • Quantum, superfluid, helium dynamics
  • Advanced Chemical Physics Studies
  • Diamond and Carbon-based Materials Research
  • Laser-Plasma Interactions and Diagnostics
  • Coal and Coke Industries Research
  • Ion-surface interactions and analysis
  • Atomic and Molecular Physics
  • Industrial Engineering and Technologies
  • Metal and Thin Film Mechanics
  • Silicon and Solar Cell Technologies
  • Advanced X-ray Imaging Techniques
  • Laser-Ablation Synthesis of Nanoparticles
  • Particle Accelerators and Free-Electron Lasers
  • Spectroscopy and Laser Applications
  • Minerals Flotation and Separation Techniques
  • Photochemistry and Electron Transfer Studies
  • Oil and Gas Production Techniques
  • Mining and Gasification Technologies
  • Coal Combustion and Slurry Processing
  • Molecular Junctions and Nanostructures
  • Laser Material Processing Techniques
  • Iron and Steelmaking Processes

Center for Integrated Quantum Science and Technology
2023-2025

University of Rostock
2014-2024

Giprokoks (Ukraine)
2009-2019

Ural Institute of Metals
1990

We report on recent experimental results deploying a continuous cryogenic hydrogen jet as debris-free, renewable laser-driven source of pure proton beams generated at the 150 TW ultrashort pulse laser Draco. Efficient acceleration reaching cut-off energies up to 20 MeV with particle numbers exceeding 10

10.1038/s41598-017-10589-3 article EN cc-by Scientific Reports 2017-08-25

Transform-limited photon emission from quantum emitters is essential for high-fidelity entanglement generation. In this Letter, we report the coherent optical property of a single negatively charged lead-vacancy (PbV) center in diamond. Photoluminescence excitation measurements reveal stable fluorescence with linewidth 39 MHz at 6 K, close to transform limit estimated lifetime measurement. We observe 4 orders magnitude different linewidths two zero-phonon lines, and find that phonon-induced...

10.1103/physrevlett.132.073601 article EN Physical Review Letters 2024-02-15

Nanodiamonds with colour centres have the potential to transform a wide range of disciplines, including quantum computation1,2, surface NMR spectroscopy3–6, single-spin magnetometry7,8, widefield microscopy9, and single photon sources10,11. However, controlled synthesis ultra-small uniform molecular ND (m-NDs) still represents great challenge. The techniques currently available only allow for production NDs that vary in terms their particle size distribution, morphology, presence undesired...

10.26434/chemrxiv-2025-hw77d preprint EN 2025-04-07

Abstract Negatively charged nitrogen‐vacancy (NV − ) centers in diamond are appealing for quantum sensing applications due to their environmental sensitivity and long coherence times. Precise scalable shallow color center creation is essential yet challenging technological applications. This the involvement of several lengthy processes, such as ion implantation thermal annealing samples. The latter process can be addressed by application an alternative activation technique that bypasses...

10.1002/adfm.202501661 article EN cc-by Advanced Functional Materials 2025-05-02

The strong-field dynamics of laser-produced nanoplasmas generated from free and size-selected silver clusters, AgN-, are analyzed by charge-state-resolving ion recoil energy spectrometry. Targeted excitation the plasmon resonance increases plasma electron temperature, which has an effect on screening, electron-ion recombination, correlated decay. By minimizing these complex contributions to expansion through plasmonic uptake, pronounced peaks show up in spectra, can be assigned emission ions...

10.1021/acs.jpclett.5c01014 article EN The Journal of Physical Chemistry Letters 2025-06-06

10.1016/0168-583x(90)90495-g article EN Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 1990-09-01

Femtosecond pump-probe electron and ion spectroscopy is applied to study the development of a helium nanoplasma up nanosecond timescale. Electrons, bound by deep confining mean-field potential, are elevated toward vacuum level in expansion. Subsequent recombination gives rise transitions between He^{+} states, resulting autoionization. The time-resolved analysis energy transfer quasifree electrons reveals transient depletion Auger emission, which allows for temporal gate map distribution...

10.1103/physrevlett.125.093202 article EN Physical Review Letters 2020-08-27

The long-time correlated decay dynamics of strong-field exposed helium nanodroplets is studied by means photoelectron spectroscopy. As a result the adiabatic expansion laser-produced, fully inner-ionized nanoplasma, delocalized electrons in deep confining mean field potential are shifted towards vacuum level. Meanwhile, part localize bound levels ions. simple hydrogenlike electronic structure He+ results clear signatures experimentally observed spectra, which can be traced back to bound-free...

10.1063/1.5089943 article EN The Journal of Chemical Physics 2019-05-22

A key feature of extreme ultraviolet (XUV) radiation from free-electron lasers (FELs) is its spatial and temporal coherence. We measured the spatio-temporal coherence properties monochromatized FEL pulses at 13.5 nm using a Michelson interferometer. time (59±8) fs has been determined, which in good agreement with spectral bandwidth given by monochromator. Moreover, vertical direction amounts to about 15% beam diameter 12% horizontal direction. The feasibility measuring XUV interferometric...

10.1063/1.4895455 article EN Applied Physics Letters 2014-09-08

The electronic properties of magnesium embedded in helium nanodroplets are investigated as a function the doping level by combining resonant two-photon ionization with photoelectron spectroscopy. Photon absorption near atomic 31P1 ← 31S0 transition triggers dynamics, which is probed on nanosecond timescale subsequent ionizing photon. Striking similarities spectra for different levels and population states well beyond evidence an energy release process being relevant wide range droplet sizes...

10.1021/acs.jpca.9b02880 article EN The Journal of Physical Chemistry A 2019-06-26

We show that rotational line spectra of molecular clusters with near zero permanent dipole moments can be observed using impulsive alignment. Aligned wavepackets were generated by non-resonant interaction intense femtosecond laser pump pulses and then probed Coulomb explosion a second, time-delayed pulse. By means Fourier transform rich spectrum eigenstates was derived. For the smallest cluster, C(2)H(2)-He, we able to establish essentially all up dissociation threshold on basis theoretical...

10.1039/c4fd00099d article EN Faraday Discussions 2014-05-27

Ion emission from a nanoplasma produced in the interaction of intense optical laser pulses with argon clusters is studied resolving simultaneously charge states and recoil energies. By applying appropriate static electric fields we observe that significant fraction ions ${\mathrm{Ar}}^{q+}$ ($q=1--7$) has electrons binding energies lower than 150 meV; i.e., ${n}_{\mathrm{Ryd}}\ensuremath{\ge}15$ levels are populated. Charge state changes observed on $\ensuremath{\mu}\mathrm{s}$ time scale...

10.1103/physrevlett.120.133207 article EN Physical Review Letters 2018-03-30

We present an extreme ultraviolet (EUV) microscope using a Schwarzschild objective which is optimized for single-shot sub-micrometer imaging of laser-plasma targets. The has been designed and constructed the scattering from EUV-heated solid-density hydrogen jet. Imaging cryogenic target was demonstrated single pulses free-electron laser in Hamburg (FLASH) at wavelength 13.5 nm. In exposure, we observe jet with ice fragments spatial resolution range. situ EUV expected to enable novel...

10.1063/1.5007950 article EN publisher-specific-oa Review of Scientific Instruments 2018-02-01

Probing the rapid dynamics of plasma evolution in laser-driven interactions provides deeper understanding experiments context ion acceleration and facilitates interplay with complementing numerical investigations. Besides microscopic scales involved, strong (self-)emission, predominantly around harmonics driver laser, often complicates data analysis. We present concept implementation a stand-alone probe laser system that is temporally synchronized to providing probing wavelengths beyond...

10.1088/1361-6587/aabf4f article EN Plasma Physics and Controlled Fusion 2018-04-19

The intensity-difference spectrum technique is applied to record charge-state resolved ion energy spectra from the Coulomb explosion of small Ar clusters under well-resolved laser intensity conditions. far-reaching control experimental parameters permits us identify a striking change in expansion pattern nanoplasma beyond given intensity. simultaneous characterization charge state and uncovers that reduction leads development low cuts yields, not present at higher fluence. complex interplay...

10.1103/physrevlett.133.073202 article EN Physical Review Letters 2024-08-16

The charging dynamics of helium droplets driven by embedded xenon cluster ignition in strong laser fields is studied comparing the abundances and highly charged Xe ions to electron signal. Femtosecond pump-probe experiments show that near optimal delay for yield increases, especially at low energies. signature can be traced back ionization environment seed electrons. Accompanying molecular simulations suggest a two-step scenario Xe-He core-shell system. In contrast xenon, experimental signal...

10.1021/acs.jpca.8b06673 article EN The Journal of Physical Chemistry A 2018-09-21

Magnesium atoms fully embedded in helium nanodroplets are exposed to two-color laser pulses, which trigger multiphoton above-threshold ionization (ATI). This allows exemplary study of the contribution a dense, neutral, and finite medium on single electron propagation. The angular-resolved photoelectron spectra show striking differences with respect results obtained free atoms. Scattering individual Mg photoelectrons, when traversing neutral environment, causes angular distribution become...

10.1021/acs.jpclett.2c00110 article EN The Journal of Physical Chemistry Letters 2022-02-08

The ionization potentials of magnesium clusters (MgN, N = 7-56) are determined by doping ultracold helium nanodroplets (HeM, M ≈ 52 000) with Mg atoms. Inspecting the particle size distributions resulting from non-resonant, short-wavelength, single-photon gives evidence that beyond a certain ensemble size, developing foam structure undergoes spontaneous collapse on way to laser interaction region. As result, hot form in relaxation process. manifests substantial change distributions, when...

10.1039/d2cp03075f article EN Physical Chemistry Chemical Physics 2022-01-01

The extreme ultraviolet plasma emission from liquid microsized argon droplets exposed to intense near-infrared laser pulses has been investigated.Emission the warm dense matter targets is recorded in a spectral range between 16 and 30 nm at intensities of 10 14 W/ cm 2 .Above threshold, soft x-ray radiation exponentially increases with pulse energy whereby strong dependence yields on duration observed, which points an effective electron collisional heating microplasma by inverse...

10.1088/1361-6455/aa9b94 article EN Journal of Physics B Atomic Molecular and Optical Physics 2017-12-29

Abstract The laser intensity dependence of the recoil energies from Coulomb explosion small argon clusters has been investigated by resolving contributions individual charge states to ion energy spectra. Between $$10^{14}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mn>10</mml:mn> <mml:mn>14</mml:mn> </mml:msup> </mml:math> and $$10^{15}$$ <mml:mn>15</mml:mn> W/cm $$^2$$ <mml:mrow /> <mml:mn>2</mml:mn> , high-energy tail spectra changes its shape develops into...

10.1140/epjs/s11734-021-00108-x article EN cc-by The European Physical Journal Special Topics 2021-05-28

Single-sized clusters of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:msubsup><a:mi>Ag</a:mi><a:mrow><a:mn>309</a:mn></a:mrow><a:mo>−</a:mo></a:msubsup></a:math> are accumulated within a digital Paul trap and exposed to intense optical laser pulses, leading the formation nanoplasmas known initial conditions, not yet feasible. Using field-free diagnostics, resulting Coulomb explosion is analyzed, giving electron distributions charge-state resolved ion energy spectra. Experiments on...

10.1103/physrevresearch.6.043276 article EN cc-by Physical Review Research 2024-12-13

The ST2 center is an optically addressable point defect in diamond that facilitates spin initialization and readout. However, while this study presents the discovery of centers first observed a natural provides reliable technique for artificially creating them, its chemical structure remains unknown. To assess potential ST2, we map out basic optical characteristics, reveal electronic level structure, quantify intrinsic transition rates. Furthermore, investigate response to microwaves, static...

10.48550/arxiv.2501.00570 preprint EN arXiv (Cornell University) 2024-12-31
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