Towards shot-noise limited diffraction experiments with table-top femtosecond hard x-ray sources

Table-top laser-driven hard x-ray sources with kilohertz repetition rates are an attractive alternative to large-scale accelerator-based systems and have found widespread applications in x-ray studies of ultrafast structural dynamics. Hard x-ray pulses of 100 fs duration have been generated at the Cu Kα wavelength with a photon flux of up to 109 photons per pulse into the full solid angle, perfectly synchronized to the sub-100-fs optical pulses from the driving laser system. Based on spontaneous x-ray emission, such sources display a particular noise behavior which impacts the sensitivity of x-ray diffraction experiments. We present a detailed analysis of the photon statistics and temporal fluctuations of the x-ray flux, together with experimental strategies to optimize the sensitivity of optical pump/x-ray probe experiments. We demonstrate measurements close to the shot-noise limit of the x-ray source.

[1]  Strain propagation in nanolayered perovskites probed by ultrafast x-ray diffraction , 2006 .

[2]  J. Hajdu,et al.  Ultrafast Bond Softening in Bismuth: Mapping a Solid's Interatomic Potential with X-rays , 2007, Science.

[3]  A. Cavalleri,et al.  Picosecond–milliångström lattice dynamics measured by ultrafast X-ray diffraction , 1999, Nature.

[4]  S. Johnson,et al.  Ultrafast Formation of a Charge Density Wave State in 1T-TaS_{2}: Observation at Nanometer Scales Using Time-Resolved X-Ray Diffraction. , 2017, Physical review letters.

[5]  T. Elsaesser,et al.  The rotating crystal method in femtosecond x-ray diffraction , 2011, 2012 Conference on Lasers and Electro-Optics (CLEO).

[6]  S. Johnson,et al.  Non-equilibrium phonon dynamics studied by grazing-incidence femtosecond X-ray crystallography. , 2010, Acta crystallographica. Section A, Foundations of crystallography.

[7]  Bahr,et al.  Kossel diffraction in perfect crystals: X-ray standing waves in reverse. , 1995, Physical review. B, Condensed matter.

[8]  T. Elsaesser,et al.  Femtosecond powder diffraction with a laser-driven hard X-ray source. , 2010, Optics express.

[9]  Juris Blums,et al.  Femtosecond X-ray measurement of coherent lattice vibrations near the Lindemann stability limit , 2003, Nature.

[10]  T. Loew,et al.  Nonlinear lattice dynamics as a basis for enhanced superconductivity in YBa2Cu3O6.5 , 2014, Nature.

[11]  Piero Macchi,et al.  Modern Charge-Density Analysis , 2012 .

[12]  I. Uschmann,et al.  Communication: The formation of rarefaction waves in semiconductors after ultrashort excitation probed by grazing incidence ultrafast time-resolved x-ray diffraction , 2016, Structural dynamics.

[13]  Hannon,et al.  Determining the phase of the structure factor by Kossel cone analysis with the use of synchrotron radiation. , 1985, Physical review. B, Condensed matter.

[14]  P Coppens,et al.  Chemical applications of X-ray charge-density analysis. , 2001, Chemical reviews.

[15]  S. Johnson,et al.  Watching the birth of a charge density wave order: diffraction study on nanometer-and picosecond-scales , 2017, 1703.07465.

[16]  T. Elsaesser,et al.  Perspective: structural dynamics in condensed matter mapped by femtosecond x-ray diffraction. , 2014, The Journal of chemical physics.

[17]  M. Bargheer,et al.  Femtosecond hard X-ray plasma sources with a kilohertz repetition rate , 2009 .

[18]  T. Elsaesser,et al.  Theoretical analysis of hard x-ray generation by nonperturbative interaction of ultrashort light pulses with a metal , 2015, Structural dynamics.

[19]  T. Elsaesser,et al.  Ultrafast large-amplitude relocation of electronic charge in ionic crystals , 2012, Proceedings of the National Academy of Sciences.

[20]  M Sikorski,et al.  A time-dependent order parameter for ultrafast photoinduced phase transitions. , 2014, Nature materials.

[21]  Harris,et al.  MeV x-ray generation with a femtosecond laser. , 1992, Physical review letters.

[22]  T. Elsaesser,et al.  Microfocus Cu-Kαsource for femtosecond x-ray science , 2005, 2005 Quantum Electronics and Laser Science Conference.

[23]  D. S. Kim,et al.  Coherent Atomic Motions in a Nanostructure Studied by Femtosecond X-ray Diffraction , 2004, Science.

[24]  Wei Li,et al.  High-average-power 2-kHz laser for generation of ultrashort x-ray pulses. , 2002, Optics letters.

[25]  W. Leitenberger,et al.  Normalization schemes for ultrafast x-ray diffraction using a table-top laser-driven plasma source. , 2012, The Review of scientific instruments.

[26]  U. Griebner,et al.  Ho:YLF chirped pulse amplification at kilohertz repetition rates - 4.3  ps pulses at 2  μm with GW peak power. , 2016, Optics letters.

[27]  Thomas Elsaesser,et al.  Ultrashort 1-kHz laser plasma hard x-ray source. , 2002, Optics letters.

[28]  B. Zhang,et al.  Note: A novel normalization scheme for laser-based plasma x-ray sources. , 2014, The Review of scientific instruments.

[29]  Brunel.  Not-so-resonant, resonant absorption. , 1987, Physical review letters.

[30]  Thomas Elsaesser,et al.  Microfocus Cu K ? source for femtosecond x-ray science , 2005 .

[31]  Thomas Elsaesser,et al.  High-brightness table-top hard X-ray source driven by sub-100-femtosecond mid-infrared pulses , 2014, Nature Photonics.

[32]  Antoine Rousse,et al.  Femtosecond x-ray crystallography , 2001 .

[33]  T. Elsaesser,et al.  Shift-current-induced strain waves in LiNbO3 mapped by femtosecond x-ray diffraction , 2016 .