title: Stimulated X-ray emission for materials science.
abstract: Resonant inelastic X-ray scattering and X-ray emission spectroscopy can be used to probe the energy and dispersion of the elementary low-energy excitations that govern functionality in matter: vibronic, charge, spin and orbital excitations. A key drawback of resonant inelastic X-ray scattering has been the need for high photon densities to compensate for fluorescence yields of less than a per cent for soft X-rays. Sample damage from the dominant non-radiative decays thus limits the materials to which such techniques can be applied and the spectral resolution that can be obtained. A means of improving the yield is therefore highly desirable. Here we demonstrate stimulated X-ray emission for crystalline silicon at photon densities that are easily achievable with free-electron lasers. The stimulated radiative decay of core excited species at the expense of non-radiative processes reduces sample damage and permits narrow-bandwidth detection in the directed beam of stimulated radiation. We deduce how stimulated X-ray emission can be enhanced by several orders of magnitude to provide, with high yield and reduced sample damage, a superior probe for low-energy excitations and their dispersion in matter. This is the first step to bringing nonlinear X-ray physics in the condensed phase from theory to application.
authors: Institute for Methods and Instrumentation of Synchrotron Radiation Research G-ISRR, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489 Berlin, Germany. martin.beye@helmholtz-berlin.de
authors: M
authors: M
authors: Beye
authors: S
authors: S
authors: Schreck
authors: F
authors: F
authors: Sorgenfrei
authors: C
authors: C
authors: Trabant
authors: N
authors: N
authors: Pontius
authors: C
authors: C
authors: Schüßler-Langeheine
authors: W
authors: W
authors: Wurth
authors: A
authors: A
authors: Föhlisch
references: Phys Rev Lett. 2011 Apr 15;106(15):153004
references: 21568552
references: Rev Sci Instrum. 2012 Dec;83(12):123109
references: 23277974
references: Nature. 2012 May 3;485(7396):82-5
references: 22522933
references: J Chem Phys. 2012 May 7;136(17):174117
references: 22583220
references: Phys Rev Lett. 2012 Apr 13;108(15):153003
references: 22587249
references: Phys Rev Lett. 1993 Mar 29;70(13):1992-1995
references: 10053438
references: Nature. 2012 Aug 30;488(7413):603-8
references: 22932384
references: Phys Rev Lett. 2002 Jul 22;89(4):043001
references: 12144479
references: Nature. 2012 Jan 25;481(7382):488-91
references: 22281598
references: Phys Chem Chem Phys. 2011 Oct 14;13(38):16941-54
references: 21887417
references: Proc Natl Acad Sci U S A. 2010 Sep 28;107(39):16772-6
references: 20805512
references: Phys Rev Lett. 2010 May 14;104(19):193002
references: 20866962
references: Phys Rev Lett. 2009 Jul 24;103(4):047401
references: 19659397