Exploring the weakest bond: Structure and ionization of the Helium Dimer, Trimer and the search for the Efimov State
Final Report Abstract
The project aimed at exploring helium dimers (He2) and trimers (He3) and their interaction with femtosecond laser pulses, synchrotron radiation, Free Electron Laser (FEL) light. The main goals were to search for the Efimov State of He3, to solve the question of the structure of ground state of He3, to image the wavefunction of the quantum halo He2 and to learn about the ionization dynamics of He2. We have reached all these goals and have in addition made (and published) many interesting (and unexpected) discoveries on the way towards reaching these goals. A total of 31 peer reviewed papers (thereof 1 in Science, 5 in NaturePhysics/Nature Communications and 11 in Phys.Rev.Lett.). We list 4 highlights from our results: 1) In 2015 we have experimentally discovered the Efimov State of He3., almost 40 years after its theoretical prediction. We obtained the first ever image of the square of the wavefunction of an Efimov state. It shows the predicted enormous size (extending to more than 100 times the size of a water molecule) and the shape of an acute triangle. This was the ultimate but also most speculative and risky goal of the project and it was not clear at all if nature would allow us to reach it. The work is published in Science (2015). 2) In a series of experiments at our femtosecond laser and at the free electron laser FLASH we imaged the wavefunction of He2.We found the atoms to about 80 % in the classically forbidden tunneling region, below a potential barrier. In this region, the wavefunction shows a strictly exponential slope, which is a universal feature across all energy scales in physics. From our measured slope we obtain a new value for the long disputed helium dimer binding energy. This result is also of interest for metrology of temperature and the determination of the Boltzmann constant. 3) We performed a coulomb explosion imaging experiment on the 4He3 ground state molecule. From this we obtained the fiercely debated 4He3 geometrical structure to be that of a random cloud while predictions had ranged from this being mainly a linear molecule to it being an equilateral triangle. We could further image also the isotop mixed 3He4He2. We found that due to the tunneling effect the mass change of the one neutron changes the size by a factor of two and also changes the geometry. The results are published in Nature Communications. 4) The discovery and spectroscopy of Interatomic Coulombic Decay in helium dimers and a direct single photon double ionization process in He2. The Interatomic Coulombic Decay turned out spectacular as it shows for the first time the vibrational structure of the wave function of the intermediate excited He2+. We have described the long and rocky road towards the discovery of the Efimov state in a popular scientific article for the DFG magazine “Forschung” which is scheduled for 2016. Physics Today (68 (7), 10 (2015)) has published a long article about our experiment and the German newspaper “Frankfurter Allgemeine Zeitung” (5.Juni 2015) published a long detailed article on our discovery of the Efimov state and the “Neue Züricher Zeitung reported on our results using Coulomb Explosion imaging (NZZ 25.2.2015 article by Uta Neubauer). Furthermore, a 25 min Interview with the PI by Alexander Kluge in the program “10vor11” was aired on RTL, a major german TV channel. Maksim Kunitski, the postdoc behind the discovery of the Efimov state, has been awarded the Michael und Biserka Baum-Award 2015.
Publications
- “Angular distributions of photoelectrons and interatomic-Coulombic-decay electrons from helium dimers: Strong dependence on the internuclear distance” Physical Review A, 82, 063405, (2010)
T. Havermeier, K. Kreidi, R. Wallauer, S. Voss, M. Schöffler, S. Schössler, L. Foucar, N. Neumann, J. Titze, H. Sann, M. Kühnel, J. Voigtsberger, N. Sisourat, W. Schöllkopf, H. Schmidt-Böcking, R. E. Grisenti, R. Dörner and T. Jahnke
(See online at https://doi.org/10.1103/PhysRevA.82.063405) - “Double-ionization mechanisms of the argon dimer in intense laser fields” Physical Review A, 82, 013412, (2010)
B. Ulrich, A. Vredenborg, A. Malakzadeh, M. Meckel, K. Cole, M. Smolarski, Z. Chang, T. Jahnke, and R. Dörner
(See online at https://doi.org/10.1103/PhysRevA.82.013412) - “Fragmentation Dynamics of CO23+ Investigated by Multiple Electron Capture in Collisions with Slow Highly Charged Ions” Physical Review Letters, 104, 103201, (2010)
N. Neumann, D. Hant, L. Ph. H. Schmidt, J. Titze, T. Jahnke, A. Czasch, M. S. Schöffler, K. Kreidi, O. Jagutzki, H. Schmidt-Böcking and R. Dörner
(See online at https://doi.org/10.1103/PhysRevLett.104.103201) - “Interatomic Coulombic Decay following Photoionization of the Helium Dimer: Observation of Vibrational Structure” Physical Review Letters, 104, 133401, (2010)
T. Havermeier, T. Jahnke, K. Kreidi, R. Wallauer, S. Voss, M. Schöffler, S. Schössler, L. Foucar, N. Neumann, J. Titze, H. Sann, M. Kühnel, J. Voigtsberger, J. H. Morilla, W. Schöllkopf, H. Schmidt-Böcking, R. E. Grisenti, and R. Dörner
(See online at https://doi.org/10.1103/PhysRevLett.104.133401) - “Interatomic Electronic Decay Driven by Nuclear Motion” Physical Review Letters, 105, 173401, (2010)
N. Sisourat, Hendrik Sann, Nikolai V. Kryzhevoi, Přemysl Kolorenč, Tilo Havermeier, Felix Sturm, Till Jahnke, Hong-Keun Kim, Reinhard Dörner and Lorenz S. Cederbaum
(See online at https://doi.org/10.1103/PhysRevLett.105.173401) - “Ion-ion coincidence studies on multiple ionizations of N2 and O2 molecules irradiated by extreme ultraviolet free-electron laser pulses” Journal of Chemical Physics, 132, 204305, (2010)
A. Yamada, H. Fukuzawa, K. Motomura, X.-J. Liu, L. Foucar, M. Kurka, M. Okunishi, K. Ueda, N. Saito, H. Iwayama, K. Nagaya, A. Sugishima, H. Murakami, M. Yao, A. Rudenko, K. U. Kühnel, J. Ullrich, R. Feifel, A. Czasch, R. Dörner, M. Nagasono, A. Higashiya, M. Yabashi, T. Ishikawa, H. Ohashi, H. Kimura, and T. Togashi
(See online at https://doi.org/10.1063/1.3436722) - “Single Photon Double Ionization of the Helium Dimer” Physical Review Letters, 104, 153401, (2010)
T. Havermeier, T. Jahnke, K. Kreidi, R. Wallauer, S. Voss, M. Schöffler, S. Schössler, L. Foucar, N. Neumann, J. Titze, H. Sann, M. Kühnel, J. Voigtsberger, A. Malakzadeh, N. Sisourat, W. Schöllkopf, H. Schmidt-Böcking, R. E. Grisenti, and R. Dörner
(See online at https://doi.org/10.1103/PhysRevLett.104.153401) - “Tracing direct and sequential two-photon double ionization of D2 in femtosecond extremeultraviolet laser pulses” Physical Review A, 81, 021401(R), (2010)
Y. H. Jiang, A. Rudenko, E. Plésiat, L. Foucar, M. Kurka, K. U. Kühnel, Th. Ergler, J. F. Pérez-Torres, F. Martín, O. Herrwerth, M. Lezius, M. F. Kling, J. Titze, T. Jahnke, R. Dörner, J. L. Sanz-Vicario, M. Schöffler, J. van Tilborg, A. Belkacem, K. Ueda, T. J. M. Zouros, S. Düsterer, R. Treusch, C. D. Schröter, R. Moshammer and J. Ullrich
(See online at https://doi.org/10.1103/PhysRevA.81.021401) - “Ultralong-range energy transfer by interatomic Coulombic decay in an extreme quantum system” Nature Physics, 6, 508, (2010)
N. Sisourat, Nikolai V. Kryzhevoi, Premysl Kolorenc, Simona Scheit, Till Jahnke and Lorenz S. Cederbaum
(See online at https://doi.org/10.1038/nphys1685) - “Breakdown of the independent electron approximation in sequential double ionization” New Journal of Physics, 13, 093008, (2011)
A. N. Pfeiffer, C. Cirelli, M. Smolarski, X. Wang, J. H. Eberly, R. Dörner and U. Keller
(See online at https://doi.org/10.1088/1367-2630/13/9/093008) - “Imaging of the Structure of the Argon and Neon Dimer, Trimer, and Tetramer” J. Phys. Chem. A, 115, 6936, (2011)
B. Ulrich, A. Vredenborg, A. Malakzadeh, L. Ph. H. Schmidt, T. Havermeier, M. Meckel, K. Cole, M. Smolarski, Z. Chang, T. Jahnke, and R. Dörner
(See online at https://doi.org/10.1021/jp1121245) - “Multiple Recapture of Electrons in Multiple Ionization of the Argon Dimer by a Strong Laser Field” Physical Review Letters, 107, 043003, (2011)
J. Wu, A. Vredenborg, B. Ulrich, L. Ph. H. Schmidt, M. Meckel, S. Voss, H. Sann, H. Kim, T. Jahnke, and R. Dörner
(See online at https://doi.org/10.1103/PhysRevLett.107.043003) - “Nonadiabatic alignment of van derWaals-force-bound argon dimers by femtosecond laser pulses” Physical Review A, 83, 061403(R), (2011)
J. Wu, A. Vredenborg, B. Ulrich, L. Ph. H. Schmidt, M. Meckel, S. Voss, H. Sann, H. Kim, T. Jahnke, and R. Dörner
(See online at https://doi.org/10.1103/PhysRevA.83.061403) - “Probing Angular Correlations in Sequential Double Ionization” Physical Review Letters, 107, 113003, (2011)
A. Fleischer, H. J. Wörner, L. Arissian, L. R. Liu, M. Meckel, A. Rippert, R. Dörner, D. M. Villeneuve, P. B. Corkum, and A. Staudte
(See online at https://doi.org/10.1103/PhysRevLett.107.113003) - “Timing the release in sequential double ionization” Nature Physics, 7, 418, (2011)
A. N. Pfeiffer, C. Cirelli, M. Smolarski, R. Dörner and U. Keller
(See online at https://doi.org/10.1038/nphys1946) - “Charge and energy transfer in argon-core-neon-shell clusters irradiated by free-electronlaser pulses at 62 nm” Physical Review A, 86, 033203, (2012)
A. Sugishima, H. Iwayama, S. Yase, H. Murakami, K. Nagaya, M. Yao, H. Fukuzawa, X.- J. Liu, K. Motomura, K. Ueda, N. Saito, L. Foucar, A. Rudenko, M. Kurka, K.-U. Kühnel, J. Ullrich, A. Czasch, R. Dörner, R. Feifel, M. Nagasono, A. Higashiya, M. Yabashi, T. Ishikawa, T. Togashi, H. Kimura, and H. Ohashi
(See online at https://doi.org/10.1103/PhysRevA.86.033203) - “Coulomb Asymmetry in Strong Field Multielectron Ionization of Diatomic Molecules” Physical Review Letters, 108, 043002, (2012)
J. Wu, M. Meckel, S. Voss, H. Sann, M. Kunitski, L. Ph. H. Schmidt, A. Czasch, H. Kim, T. Jahnke, and R. Dörner
(See online at https://doi.org/10.1103/PhysRevLett.108.043002) - “Multiorbital Tunneling Ionization of the CO Molecule” Physical Review Letters, 108, 183001, (2012)
J. Wu, L. Ph. H. Schmidt, M. Kunitski, M. Meckel, S. Voss, H. Sann, H. Kim, T. Jahnke, A. Czasch, and R. Dörner
(See online at https://doi.org/10.1103/PhysRevLett.108.183001) - “Probing the tunneling site of electrons in strong field enhanced ionization of molecules” Nature Communications, 3, 1113, (2012)
J. Wu, M. Meckel, L. Ph. H. Schmidt, M. Kunitski, S. Voss, H. Sann, H. Kim, T. Jahnke, A. Czasch, and R. Dörner
(See online at https://doi.org/10.1038/ncomms2130) - “Spatial Imaging of the H2+ Vibrational Wave Function at the Quantum Limit” Physical Review Letters, 108, 073202, (2012)
L. Ph. H. Schmidt, T. Jahnke, A. Czasch, M. Schöffler, H. Schmidt-Böcking, and R. Dörner
(See online at https://doi.org/10.1103/PhysRevLett.108.073202) - “Structures of N2Ar, O2Ar, and O2Xe dimers studied by Coulomb explosion imaging” Journal of Chemical Physics, 137, 104308, (2012)
J. Wu, M. Kunitski, L. Ph. H. Schmidt, T. Jahnke, and R. Dörner
(See online at https://doi.org/10.1063/1.4750980) - “Comparison of dissociative ionization of H2, N2, Ar2, and CO by elliptically polarized twocolor pulses” Physical Review A, 87, 023406 (2013)
J. Wu, A. Vredenborg, L. Ph. H. Schmidt, T. Jahnke, A. Czasch, and R. Dörner
(See online at https://doi.org/10.1103/PhysRevA.87.023406) - “Electron-Nuclear Energy Sharing in Above-Threshold Multiphoton Dissociative Ionization of H2” Physical Review Letters, 111, 023002 (2013)
J. Wu, M. Kunitski, M. Pitzer, F. Trinter, L. Ph. H. Schmidt, T. Jahnke, M. Magrakvelidze, C. B. Madsen, L. B. Madsen, U. Thumm, and R. Dörner
(See online at https://doi.org/10.1103/PhysRevLett.111.023002) - “Numerical simulations of single-photon double ionization of the helium dimer” Physical Review A, 88, 013407 (2013)
H. Ni, C. Ruiz, R. Dörner, and A. Becker
(See online at https://doi.org/10.1103/PhysRevA.88.013407) - “Simultaneous probing of geometry and electronic orbital of ArCO by Coulomb-explosion imaging and angle-dependent tunneling rates” Physical Review A, 88, 013422 (2013)
X. Gong, M. Kunitski, L. Ph. H. Schmidt, T. Jahnke, A. Czasch, R. Dörner, and J. Wu
(See online at https://doi.org/10.1103/PhysRevA.88.013422) - “Steering the nuclear motion in singly ionized argon dimers with mutually detuned laser pulses” Physical Review Letters 110, 033005 (2013)
J. Wu, M. Magrakvelidze, A. Vredenborg, L. Ph. H. Schmidt, T. Jahnke, A. Czasch, R. Dörner, and U. Thumm
(See online at https://doi.org/10.1103/PhysRevLett.110.033005) - “Understanding the role of phase in chemical bond breaking with coincidence angular streaking” Nature Communications, 4, 2177 (2013)
J. Wu, M. Magrakvelidze, L. Ph. H. Schmidt, M. Kunitski, T. Pfeifer, M. Schöffler, M. Pitzer, M. Richter, S. Voss, H. Sann, H. Kim, J. Lower, T. Jahnke, A. Czasch, U. Thumm, and R. Dörner
(See online at https://doi.org/10.1038/ncomms3177) - “Imaging the structure of the trimer systems 4He3 and 3He4He2” Nature Communications, 5, 5765 (2014)
Voigtsberger, Jörg, S. Zeller,J. Becht, N. Neumann, F. Sturm, H.-K. Kim, M. Waitz, F. Trinter M. Kunitski, A. Kalinin, J. Wu, W. Schöllkopf, D. Bressanini, A. Czasch, J. B. Williams, K. Ullmann-Pfleger, L. Ph H. Schmidt, M. S. Schöffler, R. E. Grisenti, T. Jahnke, and R. Dörner
(See online at https://doi.org/10.1038/ncomms6765) - “Interatomic-Coulombic-decay-induced recapture of photoelectrons in helium dimmers” Physical Review A, 90, 022515 (2014)
P. Burzynski, F. Trinter, J. B. Williams, M. Weller, M. Waitz, M. Pitzer, J. Voigtsberger, C. Schober, G. Kastirke, C. Müller, C. Goihl, F. Wiegandt, R. Wallauer, A. Kalinin, L. Ph. H. Schmidt, M. Schöffler, G. Schiwietz, N. Sisourat, T. Jahnke, and R. Dörner
(See online at https://doi.org/10.1103/PhysRevA.90.022515) - “Orientation dependence in multiple ionization of He2 and Ne2 induced by fast, highly charged ions: Probing the impact-parameter-dependent ionization probability in 11.37-MeV/u S14+ collisions with He and Ne” Physical Review A, 89, 022704 (2014)
Kim, H.-K., H. Gassert, J. N. Titze, M. Waitz, J. Voigtsberger, F. Trinter, J. Becht, A. Kalinin, N. Neumann, C. Zhou, L. Ph. H. Schmidt, O. Jagutzki, A. Czasch, M. Schöffler, H. Merabet, H. Schmidt-Böcking, T. Jahnke, H. J. Lüdde, A. Cassimi, and R. Dörner
(See online at https://doi.org/10.1103/PhysRevA.89.022704) - “Observation of the Efimov state of the helium trimer” Science, 348, 551 (2015)
Kunitski, Maksim, S. Zeller, J. Voigtsberger, A. Kalinin, L. Ph. H. Schmidt, M. Schöffler, A. Czasch, W. Schöllkopf, R. E. Grisenti, T. Jahnke, D. Blume and R. Dörner
(See online at https://doi.org/10.1126/science.aaa5601) - „Das ganze Bild aus Bruchstücken“ Physik Journal, Nr. 8/9, Page 62-64 (2015)
Moshammer, Robert, Reinhard Dörner
- “Imaging the He2 quantum halo state using a free electron laser “
S. Zeller, M. Kunitski, J. Voigtsberger, A. Kalinin, A. Schottelius, C. Schober, M. Waitz, H. Sann, A. Hartung, T. Bauer, M. Pitzer, F. Trinter, C. Goihl, C. Janke, M. Richter, G. Kastirke, M. Weller, A. Czasch, M. Kitzler, M. Braune, R. E. Grisenti, W. Schöllkopf, L. Ph. H. Schmidt, M. Schöffer, J. B. Williams, T. Jahnke, R. Dörner
(See online at https://doi.org/10.1073/pnas.1610688113)
