1 Acknowledgements Collaborators from Fritz Haber Institute Wieland
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Acknowledgements § Collaborators from Fritz Haber Institute - Wieland Schöllkopf - Weiqing Zhang § Funds 2
AMOL (Atom & Molecule Optics Lab) Members Lee Ju Hyeon Kim Hye ah Kim Lee Yeong Bong Jun Kim Byung Gwun Jin Xing Nan Sun Bum Suk Zhao
AMOL (Atom & Molecule Optics Lab) Research Topics § Manipulating external motions of molecules with laser fields • at UNIST in Ulsan § Grazing incidence atom/molecule optics • at Fritz Haber Institute in Berlin
Universal diffraction of atoms and molecules from a quantum reflection grating 6 Bum Suk Zhao (조범석) Department of Chemistry, Department of Physics Ulsan National Institute of Science and Technology
Universal diffraction of He, He 2 and D 2 from a quantum reflection grating 7 Bum Suk Zhao (조범석) Department of Chemistry, Department of Physics Ulsan National Institute of Science and Technology
Optical phenomena with matter waves of atoms and molecules § de Broglie wavelength § He atom diffraction from a Li. F crystal proof of wave property of atoms 8 I. Estermann and O. Stern, Z. Phys. . 61, 95 (1930)
Optical phenomena with matter waves of atoms and molecules § Three grating interferometer for matter waves of molecules § Talbot-Lau interferometer (TLI) • 9 C 60, C 70 (m = 840 amu) § Kapitza-Dirac-Talbot-Lau interferometer (KDTLI) • m = 7000 amu Gerlich, S. et al. , Nat. Phys. 3, 711 (2007) T. Juffmann, H. Ulbricht, M. Arndt, Rep. Prog. Phys. 76 (2013)
The analogy between classical and atom/molecule optics is not exact § Diffraction peak intensities of He and D 2 (with the same ld. B) scattered from a crystal surface were found to strongly differ. 10 M. F. Bertino, F. Hofmann, and J. P. Toennies, J. Chem. Phys. 106, 4327 (1997)
The analogy between classical and atom/molecule optics is not exact § three grating experiments KDTLI 11
The analogy between classical and atom/molecule optics is not exact § three grating experiments KDTLI 12
The analogy between classical and atom/molecule optics is not exact § three grating experiments KDTLI TLI 13
The analogy between classical and atom/molecule optics is not exact § The interaction of particles with either an external field or with the material of an optical element - results in the particle-dependent properties of matter waves - modifies or suppresses the matter-wave optical phenomena such as diffraction intensities and interference effects § The matter-wave optical phenomena is not only determined by ld. B but also by the properties of the particles 14
Minimizing particle-surface interaction § An atomically thin matter-wave beamsplitter phthalocyanine (m = 514) 15 Brand, C. et al. Nat. Nanotech. 10, 845 (2015)
Minimizing particle-surface interaction § Quantum reflection of particles tens of nanometers above a surface 16 B. S. Zhao*, G. Meijer and W. Schöllkopf, Science 331, 892 (2011)
Universal diffraction of He, He 2 and D 2 from a quantum reflection grating § “emerging beam resonances” of identical shape for He atoms, D 2 molecules, and even helium dimers, He 2 17
Outline § Introduction quantum reflection He 2 emerging beam resonance § Experimental setup § Result and discussion emerging beam resonance of He 2 universal diffraction of He, He 2, D 2 § Summary 18
Classical mechanics transmitted incident § A particle passes through a potential step with 100% probability 19
Quantum mechanics transmitted for x > 0 for x < 0 incident reflected § finite probability of being reflected at a potential step § Reflectivity |R|2 is obtained using continuity of y and dy/dx at x=0 20
Quantum mechanics transmitted incident reflected When Kin 0, |R|2 1 § finite probability of being reflected at a potential step § Reflectivity |R|2 is obtained using continuity of y and dy/dx at x=0 21
Potential step formed by particle-surface interaction potential V(z) 22
Potential step formed by particle-surface interaction potential V(z) 23
Grazing incidence angle of a few mrad provides vz < 1 m/s V(z) Kz, in = (mvz 2)/2 24
Quantum reflection several nanometers above a surface V(z) Kz, in = (mvz 2)/2 = |V(z 0)| 25 H. Friedrich et al. , Phys. Rev. A 65, 032902 (2002) (Theory)
Helium dimer: ‘fragile giant’ § Theoreticians calculated a helium pair potential [1] and a molecular wave function [2] of the He 2 binding energy |Eb| = 1. 1 m. K = 0. 1 me. V = 2. 3 mcal/mol (~ 10 e. V for H 2) 26 [1] Tang, Toennies, and Yiu, Phys. Rev. Lett. 74, 1546 (1995) [2] Lewerenz, J. Chem. Phys. 106, 4596 (1997)
He 2 can be reflected tens of nanometers above a surface without passing a potential well qin ~ 0. 39 mrad Kin = (3. 2 me. V)(sinqin)2 = 0. 57 ne. V 40 nm potential well depth ~ 10 me. V 27 B. S. Zhao, G. Meijer and W. Schöllkopf, Science 331, 892
Emerging beam resonance (Rayleigh-Wood anomaly in optics) qin = q. R, m § Rayleigh(-Wood) anomaly (i) a sharp intensity variation (ii) related exclusively to the emergence of a diffracted beam (iii) occurring at the Rayleigh conditions (angle or wavelength) § General aspects of emerging beam resonances can be explained with multiple scattering approach 28 Lord Rayleigh, Phil. Mag. 14, 60 (1907) U. Fano, J. Opt. Soc. Am. 31, 213 (1941)
Multiple scattering model qin < q. R, m secondary scattering direct scattering amplitude of nth-diffraction-order, Sn = Sn(1) + Sn(2) 29 Lord Rayleigh, Phil. Mag. 14, 60 (1907) U. Fano, J. Opt. Soc. Am. 31, 213 (1941)
Multiple scattering model qin < q. R, m qin = q. R, m secondary scattering direct scattering amplitude of nth-diffraction-order, Sn = Sn(1) + a. Sm emergence of mth-diffraction-order Sn(2) ∝ Sm , Sn(1) and Sn(2) are in phase 30 Lord Rayleigh, Phil. Mag. 14, 60 (1907) U. Fano, J. Opt. Soc. Am. 31, 213 (1941)
Multiple scattering model qin < q. R, m qin = q. R, m secondary scattering direct scattering amplitude of nth-diffraction-order, Sn = Sn(1) + a. Sm emergence of mth-diffraction-order Sn(2) ∝ Sm , Sn(1) and Sn(2) are in phase 31 increase of In ( intensity of of nth-diffraction-order)
Multiple scattering model qin < q. R, m qin = q. R, m secondary scattering direct scattering amplitude of nth-diffraction-order, Sn = Sn(1) + Sn(2) separation of mth-diffraction-order from grating Sn(2) ∝ Sm 32 increase of In stops abruptly qin > q. R, m
Observation of emerging beam resonance in atom optics § We will test the universal diffraction behavior by comparing the abrupt intensity variation of He, He 2 and, D 2 near q. R, m qin > q. R, -1 qin ~ q. R, -1 33 B. S. Zhao*, G. Meijer and W. Schöllkopf*, Phys. Rev. Lett. 104, 240404 (2010)
Experimental setup 34
Experimental setup (schematic) 35
Cryogenic molecular beam source nozzle condition i) diameter: 5 mm ii) T 0 = 4 ~ 300 K iii) P 0 = 0. 1 ~ 150 bar 36
High collimation slits 37 Highly collimated, continuous beam • divergence: below 50 mrad • angular resolution: ~110 mrad (FWHM)
Rotatable mass spectrometer 38
Definition of angles incidence angle qin detection angle q azimuth angle f 39
By rotating the plane ruled grating we can control the effective periodic length deff plane ruled blazed grating (Newport 20 RG 050 -600 -1) • period, d = 20 mm • blazing angle, a = 14 mrad • 6 -mm-thick glass with an aluminum coating 40
By rotating the plane ruled grating we can control the effective periodic length deff 41
By rotating the plane ruled grating we can control the effective periodic length deff 42 B. S. Zhao*, G. Meijer and W. Schöllkopf*, Phys. Rev. Lett. 104, 240404 (2010) B. S. Zhao*, G. Meijer and W. Schöllkopf, New J. Phys. 13, 065017 (2011)
Diffraction patterns of He and He 2 obtained with T 0 = 8. 7 K and P 0 = 1 bar 43
Diffraction patterns of He and He 2 obtained with T 0 = 8. 7 K and P 0 = 1 bar 44
Diffraction patterns of He and He 2 obtained with T 0 = 8. 7 K and P 0 = 1 bar 45
Emerging beam resonance of He 2 qin < q. R, -1 46
Emerging beam resonance of He 2 qin < q. R, -1 47 qin = q. R, -1
Emerging beam resonance of He 2 qin < q. R, -1 48 qin = q. R, -1 qin > q. R, -1
Emerging beam resonance of He 2 49 B. S. Zhao*, W. Zhang and W. Schöllkopf*, Sci. Adv. 2, e 1500901 (2016)
Emerging beam resonance of He 2 1. He 2 at ~30 nm above a surface 2. evanescence wave of He 2 3. multiple scattering of He 2 50 B. S. Zhao*, W. Zhang and W. Schöllkopf*, Sci. Adv. 2, e 1500901 (2016)
He, He 2 and D 2, with the same ld. B = h/mv = 0. 17 nm T 0 (K) He He 2 D 2 35 8. 7 35 1 0. 8 P 0 (bar) 7. 3 51 velocity v v/2 v mass m 2 m m Kin Kin/2 Kin C 3 2 C 3 4 C 3 l l l 2 l
Secondary scattering phase shift § Rule of thumb § We assume the wave vector k to be constant along the path deff between the first and second scattering 52 B. S. Zhao*, W. Zhang and W. Schöllkopf*, Sci. Adv. 2, e 1500901 (2016)
Secondary scattering phase shift § the particle-surface potential-induced phase shift at qin = q. R, m constructive interference between direct and secondary scattering 53 B. S. Zhao*, W. Zhang and W. Schöllkopf*, Sci. Adv. 2, e 1500901 (2016)
Secondary scattering phase shift § F depends on ld. B as the sole parameter § universal behavior for any atom or molecule at a given ld. B (although the Casimir-Polder potential is particle-specific) 54 B. S. Zhao*, W. Zhang and W. Schöllkopf*, Sci. Adv. 2, e 1500901 (2016)
Universal diffraction of He, He 2, and D 2 55 B. S. Zhao*, W. Zhang and W. Schöllkopf*, Sci. Adv. 2, e 1500901 (2016)
Universal diffraction of He, He 2, and D 2 56 B. S. Zhao*, W. Zhang and W. Schöllkopf*, Sci. Adv. 2, e 1500901 (2016)
Universal diffraction of He, He 2, and D 2 He D 2 W. Zhang, J. H. Lee, H. A. Kim, B. G. Jin, B. J. Kim, L. Y. Kim, B. S. Zhao and W. Schöllkopf, Chem. Phys. Chem. 12 (2016) M. F. Bertino, F. Hofmann, and J. P. Toennies, J. Chem. Phys. 106, 4327 (1997)
Summary § Emerging beam resonance of He, He 2, and D 2 § Nondestructive multiple scattering of fragile He 2 § Universal diffraction of atoms and molecules 58
Experimental studies on evanescent waves in atom and molecule optics 2. Manipulation of atom beam through evanescent wave state • A: producing evanescent wave • B: detecting evanescent wave • periods: two different periods d. A and d. B • shapes: producing strong evanescent wave 59
Wood observed anomalous intensity variations in white light diffraction from a ruled grating wavele (diffrac ngth tion an gle) Incidence angle grating normal white light diffraction from a ruled grating 60 R. W. Wood, Phil. Mag. 4, 396 (1902)
Wood observed anomalous intensity variations in white light diffraction from a ruled grating incidence angle wavelength dark and bright bands 61 R. W. Wood, Phil. Mag. 4, 396 (1902)
Emerging beam resonance (Rayleigh-Wood anomaly in optics) History of Wood’s anomaly in wave optics Light optics Electron optics Atom optics emergence type Rayleigh anomaly (1902) threshold effect (1933) Emerging beam resonance (2010) resonance type resonance anomaly (1902) electron surface resonance (1933) selective adsorption (1930) R. W. Wood, Phil. Mag. 4, 396 (1902) I. Estermann and O. Stern, Z. Phys. . 61, 95 (1930) S. Kikuchi and S. Nakagawa. Sci. Pap. Inst. Phys. Chem. Res. Tokyo 21, 256 (1933) B. S. Zhao, G. Meijer and W. Schöllkopf, Phys. Rev. Lett. 104, 240404 (2010) 62
Emerging beam resonance (Rayleigh-Wood anomaly in optics) qin < q. R, m qin = q. R, m secondary scattering direct scattering l 2 l 1 amplitude of nth-diffraction-order, Sn = Sn(1) + Sn(2) emergence of mth-diffraction-order Sn(2) ∝ Sm , Sn(1) and Sn(2) are in phase l 1 - l 2 = ml 63
Basic studies on grazing incidence atom and molecule optics reciprocity theorem in grazing incidence atom and molecule optics In = 1 = Im = -1 • informs us the reverse process of evanescent wave formation • directly linked to the basic concept of time reversal symmetry 64
Different diffraction efficiency of He and D 2 M. F. Bertino, F. Hofmann, and J. P. Toennies, J. Chem. Phys. 106, 4327 (1997)
The He 2 peak appears between the two He peaks with He 3 peaks being suppressed at P 0 = 1 bar Incidence angle: qin = q 0 = 0. 39 mrad T 0 = 8. 7 K Effective period is determined by monomer peak positions. • deff = 2 mm • f ~ (0. 02 mm)/(2 mm) = 10 mrad B. S. Zhao, G. Meijer and W. Schöllkopf, Science 331, 892 (2011)
The He 2 peak appears between the two He peaks with He 3 peaks being suppressed at P 0 = 1 bar Incidence angle: qin = q 0 = 0. 39 mrad T 0 = 8. 7 K Effective period is determined by monomer peak positions. • deff = 2 mm • f ~ (0. 02 mm)/(2 mm) = 10 mrad 1 st-order He 2 peak between He peaks T 0 = 8. 7 K He 2+ mass channel: • no He contribution • weak He 2 peak due to fragmentation Higher P 0 = 2 bar: • additional He 3 peaks Bruch et al. , J. Chem. Phys. 117, 1544 (2002) B. S. Zhao, G. Meijer and W. Schöllkopf, Science 331, 892 (2011)
The analogy between classical and atom/molecule optics is not exact § Diffraction patterns of He and He 2 (with the same ld. B) diffracted from a transmission grating would be different by about 3 nm because of their different effective slit width seff(He) = 68. 7 nm seff(He 2) = 65. 3 nm 68 R. E. Grisenti et al. , Phys. Rev. Lett. 85, 2284 (2000)
Theoreticians have studied emerging beam resonances in atom scattering G. Armand J. Manson, Surf. Sci. 169, 216 (1986)
Theoreticians have studied emerging beam resonances in atom scattering 1. occurring over a narrow angular range of 0. 005° (~ 85 mrad) G. Armand J. Manson, Surf. Sci. 169, 216 (1986)
Theoreticians have studied emerging beam resonances in atom scattering 1. occurring over a narrow angular range of 0. 005° (~ 85 mrad) 2. small emerging-order intensity G. Armand J. Manson, Surf. Sci. 169, 216 (1986)
Theoreticians have studied emerging beam resonances in atom scattering 1. occurring over a narrow angular range of 0. 005° (~ 85 mrad) 2. small emerging-order intensity G. Armand J. Manson, Surf. Sci. 169, 216 (1986) high collimation and angular resolution of detection B. S. Zhao (조범석), G. Meijer and W. Schöllkopf, Phys. Rev. Lett. 104, 240404 (2010)
Secondary scattering phase shift § the potential energy probed by the particle along the additional path of length deff 73 B. S. Zhao*, W. Zhang and W. Schöllkopf*, Sci. Adv. 2, e 1500901 (2016)
Secondary scattering phase shift § the particle-surface potential-induced phase shift 74 B. S. Zhao*, W. Zhang and W. Schöllkopf*, Sci. Adv. 2, e 1500901 (2016)
Secondary scattering phase shift § the particle-surface potential-induced phase shift at qin = q. R, m 75 B. S. Zhao*, W. Zhang and W. Schöllkopf*, Sci. Adv. 2, e 1500901 (2016)
Diffraction through a transmission grating provided unequivocal evidence of He 2 N: # of He atoms in cluster velocity v: same for all particles Detection angle q [mrad] 76 W. Schöllkopf and P. Toennies, Science 266, 1345 (1994)
Emerging beam resonance (Rayleigh-Wood anomaly in optics) qin = q. R, m § Rayleigh(-Wood) anomaly (i) a sharp intensity variation (ii) related exclusively to the emergence of a diffracted beam (iii) occurring at the Rayleigh conditions (angle or wavelength) § General aspects of emerging beam resonances can be explained with multiple scattering approach 77 Lord Rayleigh, Phil. Mag. 14, 60 (1907) U. Fano, J. Opt. Soc. Am. 31, 213 (1941)
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