High-Resolution Soft X-ray RIXS Beamline

Transcription

1 High-Resolution Soft X-ray RIXS Beamline Di-Jing Huang Jan 15, 2009

2 Science D. J. Huang (NSRRC), RIXS spectroscopy C. T. Chen (NSRRC), AGS-AGM design and RIXS spectroscopy S-W. Cheong (Rutgers University), material synthesis F. C. Chou (National Taiwan University), material synthesis C. L. Dong (NSRRC), ), RIXS spectroscopy A. Fujimori (University of Tokyo), RIXS spectroscopy C. Y. Mou (National Tsing Hua University), theory L. H. Tjeng (Cologne University), RIXS spectroscopy M. K. Wu (Scademia Sinica), material synthesis Beamline Design & Construction S. C. Chung(NSRRC), coordinator H. S. Fung (NSRRC), design of beamline & spectrometer W. B. Wu(NSRRC), beamline construction C. S. Lee (NSRRC), mechanical drawing.. 2

3 Outline Overview of Scientific Scope Design of the AGM-AGS Beamline Commissioning Results of the AGM-AGS with TLS Reply to SAC comments 3

4 Outline Overview of Scientific Scope Design of the AGM-AGS Beamline Commissioning Results of the AGM-AGS with TLS Reply to SAC comments 4

5 Energy Scale of Low-energy Excitations in Complex Materials ev 3 Mott/CT gaps 2 dd Excitations Orbitons Multimagnons Pseudogaps Magnons/Spin-flips Superconducting gap 5

6 a b Low-energy excitations interactions Resonant Inelastic X-ray Scattering (RIXS) a n b Charge, orbital, and spin 6

7 RIXS in the soft X-ray regime is powerful spectroscopy tool! 7

8 RIXS in the soft X-ray regime is powerful spectroscopy tool! Collective Magnetic Excitations in the Spin Ladder Sr 14 Cu 24 O 41 Measured Using High-Resolution Resonant Inelastic X-Ray Scattering J. Schlappa et al., Phys. Rev. Lett. 103, (2009) 8

9 RIXS in the soft X-ray regime is powerful spectroscopy tool! 9

10 Rare earth f-systems (mixed valence, heavy fermions, Kondo problem ) Classic examples S.M. Butorin, PRL 77 (1996) ;Theory by Kotani M. Magnuson et al., PRB 63, (2001) ;Theory by Kotani Crystal field excitation of YbN: RIXS Intermediate state 3d 5/2 4f 14 4f 13 Γ 7 Γ 8 Γ 6 81 mev 33 mev 0 mev Kondo excitation in Yb 3d RIXS of YbInCu4 3d 5/2 4f 14 c k A. Kotani, Workshop on soft-x-ray scattering (Oct. 2009) 4f 14 +4f 13 c Low excited states k B T K ~ 40 mev 10 Singlet bound state

11 RIXS is also a versatile photon-in/photon-out probe Considerations of in situ studies with RIXS- -Need an environmental cell (Liquid cell & gas cell) -Thin membrane (100nm Si 3 N 4 or carbon window) Solid sample Liquid cell In Window In Wet sample out out O-ring Transmission (%) Courtesy of J.-H. Guo (ALS) Fe 2p (82%) O 1s (66%) C_100nm; SiC_100nm Si_100nm; SiN_100nm C 1s (46%) Al_100nm Energy (ev) 100nm Si 3 N 4, ~4 µl liquid volume, Wet sample Liquid in In Window In Window Gas cell In Window out out Liquid flow Liquid out Reaction area Sample out Gas flow 66% Vacuum pressure < 1 x 10-9 Torr Gas Reaction area Sample

12 Static liquid cell From concept Photon-in Photon-out To reality liquid Nanoparticle suspension FPM O-ring Co Nanoparticles with Ligand Molecules 100 nm thick SiN membrane (Cell designed by Uppsala, Sweden & ALS) Co nanocrystals grwoth mechanism Nanocrystals interact more strongly with solvent molecules in the initial stages of growth, while at a later stage, the interaction is dominated by the oleic acid surfactant. HongjianLiu, et al., NanoLetters 7, 1919 (2007) Surfactant: Oleic Acid, C 18 H 34 O 2 [CH 3 (CH 2 ) 7 CH:CH(CH 2 ) 7 CO 2 H] Solvent: Dichlorobenzene, C 6 H 4 Cl 2 12

13 Flow liquid cell Static liquid cell: (only one 1b 1 feature) J.-H. Guo et al., PRL 89, (2002) M. Odelius et al., PRL 94, (2005) Isotope and temperature effects in Liquid water O. Fuchs, et al., PRL 100, (2008) Isotope effect Temperature effect 1b 1 1b 1 1b 1 Only one broad 1b 1 feature at lower energy resolution for liquid water. Three occupied molecular orbitals: 1b 2, 3a 1 and 1b 1 1b 1 turns into 1b 1 peak has dependence on phase and temperature 1b 1 : Intact water molecular 1b 1 : Ultrafast molecular dissociation. The splitting of 1b 1 has not been predicted by any theoretical simulation model! 13

14 Outline Overview of Scientific Scope Design of the AGM-AGS Beamline Commissioning Results of the AGM-AGS with TLS Reply to SAC comments 14

15 A Conventional SGM Beamline for IXS Measurements High performance Simple optical layout Refocusing Mirror Varied-Line-Space (VLS) Grating V. Focusing Mirror Entrance Slit H. Focusing Mirror Source Sample Movable Exit slit to eliminate the defocus aberration Grating Detector Major optical aberrations: defocus & comma aberrations 15

16 Invited talk, 8 th SRI, 2003 H. S. Fung et al. AIP Conf. Proc. 705, 655 (2004). 16

17 Optical Concept of the AGM-AGS Beamline Energy Compensation Principle Entrance slit H. S. Fung et al. AIP Conf. Proc. 705, 655 (2004). sample hω + ε Active Grating hω ε 17

18 Optical Concept of the AGM-AGS Beamline Energy Compensation Principle Entrance slit H. S. Fung et al. AIP Conf. Proc. 705, 655 (2004). sample hω + ε hω ε Active Grating 18

19 Optical Concept of the AGM-AGS Beamline Entrance slit Energy Compensation Principle H. S. Fung et al. AIP Conf. Proc. 705, 655 (2004). CCD sample hω ± ε hω + ε hω + ε hω± ε Active Grating (monochromator) AGM hω ε hω ε ε, << hω Active Grating (spectrometer) AGS 19

20 Source A Active VLS Grating grating profile 2 3 ( w) aw aw ξ = B α β Grove density of VLS n( w) = n0 + nw 1 +L w A VLS grating can focus photons onto a nearly vertical plane, satisfying much better the condition of energy compensation. Grating equation sinβ sinα = kn0λ 20

21 Optical design of the AGM-AGS RIXS beamline Active Grating: Position of the exit slit fixed Coma aberration eliminated Slit V. Focusing Mirror H. Focusing Mirror EPU AGM Sample AGS CCD 21

22 Simulation with varied-line-spacing grating 1000 ev For resolving power =10000 E=93 mev at Cu L 3, and 53 mev, at O K-edge. (e.g. SLS ADRESS) A resolving power of can be achieved with a perfect grating. H. S. Fung et al. AIP Conf. Proc. 705, 655 (2004). 22

23 Simulated Energy Loss Spectrum with VLS Gratings H. S. Fung et al. AIP Conf. Proc. 705, 655 (2004). Relative Intensity mev mev 84 mev 0.2 Limited to a small range of energy-loss window Energy Loss (ev) The AGS grating is optimized for 1.5 ev energy loss. r 1 = 3.5 m r 2 = 2.5 m n 0 = 1200 /mm n 1 = 0.8 /mm 2 E in = 800 ev ε = 8 ev 23

24 Requirement of the Energy Compensation Principle Grating equation sinβ sinα = kn0λ Only the values of r 2 and n 0 are required to be the same for AGM and AGS. r 2 M AGM r 1 M Slit V. Focusing Mirror H. Focusing Mirror EPU n( w) = n0 + nw 1 +L Sample r 2 S AGS r 1 S CCD The values of n 1 for AGM and AGS can be independently fine tuned. 24

25 Expected AGM-AGS System 900 ev Zero slope error of grating C:\NSRRC_Project\TPS_EPU\Case_V\ray_tracing\AGS_fix_R(n1=-22)\900eV\resolt(n1=-22) E c =900 ev E=+/ ev Entrance slit opening: 2 µm n 0 = 1200 grooves/mm AGM_n 1 = 0.88 grooves/mm 2 AGS_n 1 = grooves/mm 2 19 mev (FWHM) C:\NSRRC_Project\TPS_EPU\Case_V\ray_tracing\AGS_fix_R(n1=-22)\900eV\resolt(n1=-22) 17 mev (FWHM) 17 mev (FWHM) Energy Loss (ev) Energy Loss (ev) 25

26 Expected AGM-AGS System 900 ev Slope error of grating: 0.25 mrad (RMS) E c =900 ev E=+/ ev Entrance slit opening: 2 µm n 0 = 1200 grooves/mm AGM_n 1 = 0.88 grooves/mm 2 AGS_n 1 = grooves/mm 2 Gratings slope error: 0.25 µrad(rms) 40 mev (FWHM) mev(fwhm) m e V W H Energy Loss (ev) Energy Loss (ev) 26

27 Expected AGM-AGS System 500 ev Zero slope error of grating E c = 500 ev, E=+/ ev Entrance slit opening: 2 µm n 0 = 600 grooves/mm AGM_n 1 = 0.37 grooves/mm 2 AGS_n 1 = grooves/mm mev (FWHM) 8 m e V (F W H M) Energy Loss (ev) 10 mev (FWHM) Energy Loss (ev) 27

28 Expected AGM-AGS System 500 ev Slope error of grating: 0.25 mrad (RMS) E c = 500 ev, E=+/ ev n 0 = 600 grooves/mm AGM_n 1 = 0.37 grooves/mm 2 AGS_n 1 = grooves/mm 2 Gratings slope error: 0.25 µrad (RMS) m e V (F W H M) mev (FWHM) Energy Loss (ev) Energy Loss (ev) 28

29 Would be the World-Best RIXS Setup in Soft X-Ray Range Ultra-high energy 900 ev: E/DE 40,000 (0.1-mrad slope error), sample = /sec (900 ev) Sample Beam size ~ 54 mm (H) 20,000 (0.25-mrad slope error) AGM r 2 =2.5 r 1 = 3.5 AGS Grating efficiency =0.1 Slit R = 0.5 V. Focusing Mirror in units of m Vertical beam size < 2 the entrance slit (demagnification=10) Flux = BW, 900 ev R = 0.65 H. Focusing Mirror EPU Source size 10 mm (V) 165 mm (H) CCD 29

30 In Comparison with the ADRESS beamline 800 l/mm: 1.3x10 13 ph/s in a bandwidth, E/ΔE= l/mm: 1.7x10 12 ph/s in a bandwidth, E/ΔE= l/mm: 2.4x10 11 ph/s in a bandwidth, E/ΔE=20000 courtesy of T. Schmitt 30

31 Outline Overview of Scientific Scope Design of the AGM-AGS Beamline Commissioning Results of the AGM-AGS with TLS Reply to SAC comments 31

32 ±40 32

33 Sample chamber AGM-AGS Inelastic Scattering Setup Monochromator Entrance slit Spectrometer Sample chamber CCD detector 33

34 RIXS of NiO Aperture (mm) Energy Compensation Principle Total energy resolution FWHM=270 mev elastic peak aperture Energy Loss (ev) 0 34

35 RIXS of NiO Ψ 3d F G Ψ 2 p H x 2 I J K Energy Loss (ev) 0 Ghiringhelli et al. J. Phys.: Condens. Matter (2005)

36 G. Ghiringhelliet al., PRL (2009) 1 E g 3 T 1g e g t 2g e g 3 T 2g NiO dd excitations 3 T 2g t 2g Counts e g T 1g 1 d 8 E g + 3 T 1g t2g 3 A 2g Energy Loss (ev) 36

37 Quantum Multiferroic LiCu 2 O 2 O 2- Cu 2+ Li 1+ Cu 1+ Cu 2+ : d 9 + d 10 L d xy hole Cu + : d 10 + d 9 4s 1 + d 10 4s 1 L d z hole S. W. Huang et al., RL(2008) XAS (001) θ C. L. Chen et al., PRB(2008) 37

38 XAS E ^ c Total energy resolution FWHM=210 mev Aperture = 100 mm 38

39 Outline Overview of Scientific Scope Design of the AGM-AGS Beamline Commissioning Results of the AGM-AGS with TLS Reply to SAC comments 39

40 Comments of SAC review in 2009 Proposal #5 has the potential to be world leading and includes a complete team with expertise in x-ray science, materials, and theory. The scope can be broadened to include the components of proposal #4 which includes excellently trained, young scientists. Reply: Scientific Subjects Strongly correlated compounds: transition-metal oxides Heavy-fermion compounds: rare-earth materials liquids New member: C. L. Dong (NSRRC) PhD students - S. W. Huang (National Chiao-Tung University) - Huang (National Tsing Hua University) - Lai (National Tsing HuaUniversity)

41 Hasa RIXS spectrum been smeared out by using the energy compensation principle? Within the liftetimebroadening of XAS, RIXS obtained by using the conventional method is insensitive to the incident photon energy. G. Ghiringhelliet al., PRL (2009)

42 Acknowledgement T. Schmitt, V. N. Strocov, J. Friso van der Veen G. Ghiringhelli 42

43 Thank you!