The advance of matter optics, thus the coherent scattering of an atom or molecule beam from a nanostructured grating, recently gave conclusive evidence for the extremely weakly bound diatomic and triatomic van der Waals clusters of helium in a precision experiment. A quantum mechanical multi-channel many-body scattering theory, as it is presented and extended in this work, is essential for the quantitative description of such an experiment. In order to enhance the resolution of the most recent measurements the grating was tilted with respect to the incident beam. At first, the asymmetry of the diffraction pattern caused by this was theoretically studied for the case of atom diffraction. Subsequently, the ground state of the helium trimer was investigated and its bond length determined to be about 1 nm. Another part of this work considers inelastic diffraction and shows, using small hydrogen dimers as an example, that matter optics allows, in principle, for the spectroscopy of weakly bound clusters.The advance of matter optics, thus the coherent scattering of an atom or molecule beam from a nanostructured grating, recently gave conclusive evidence for the extremely weakly bound diatomic and triatomic van der Waals clusters of helium in a precision experiment. A quantum mechanical multi-channel many-body scattering theory, as it is presented and extended in this work, is essential for the quantitative description of such an experiment. In order to enhance the resolution of the most recent measurements the grating was tilted with respect to the incident beam. At first, the asymmetry of the diffraction pattern caused by this was theoretically studied for the case of atom diffraction. Subsequently, the ground state of the helium trimer was investigated and its bond length determined to be about 1 nm. Another part of this work considers inelastic diffraction and shows, using small hydrogen dimers as an example, that matter optics allows, in principle, for the spectroscopy of weakly bound clusters.

Jan 1, 20040 citations

Observation of Mixed Fermionic-Bosonic Helium Clusters by Transmission Grating Diffraction

Anton Kalinin, Oleg Kornilov, Wieland Schöllkopf +1 more

Small weakly bound boson-fermion $^{4}\mathrm{He}_{m}^{3}\mathrm{He}_{n}$ clusters formed in a free jet expansion are identified using nondestructive transmission grating diffraction. The observations confirm the existence of more than 11 very tenuous complexes including the three-body halo molecule $^{4}\mathrm{He}_{2}^{3}\mathrm{He}$ and the pseudo-Borromean complex $^{4}\mathrm{He}_{2}^{3}\mathrm{He}_{2}$ . Effective cluster formation temperatures, extracted from a sudden freeze model for cluster growth using theoretical binding energies, increase smoothly with cluster size, thereby confirming the calculations with the possible exception of $^{4}\mathrm{He}_{2}^{3}\mathrm{He}_{2}$ .Small weakly bound boson-fermion $^{4}\mathrm{He}_{m}^{3}\mathrm{He}_{n}$ clusters formed in a free jet expansion are identified using nondestructive transmission grating diffraction. The observations confirm the existence of more than 11 very tenuous complexes including the three-body halo molecule $^{4}\mathrm{He}_{2}^{3}\mathrm{He}$ and the pseudo-Borromean complex $^{4}\mathrm{He}_{2}^{3}\mathrm{He}_{2}$. Effective cluster formation temperatures, extracted from a sudden freeze model for cluster growth using theoretical binding energies, increase smoothly with cluster size, thereby confirming the calculations with the possible exception of $^{4}\mathrm{He}_{2}^{3}\mathrm{He}_{2}$.

Physical Review LettersSep 9, 200521 citations

Dynamics of Helium Clusters

S. Stringari

NATO ASI series. Series B : PhysicsJan 1, 19910 citations

Matter Wave Diffraction from an Inclined Transmission Grating: Searching for the Elusive H4e Trimer Efimov State

Rüdiger Brühl, Anton Kalinin, Oleg Kornilov +3 more

The size of the helium trimer is determined by diffracting a beam of 4He clusters from a 100 nm period grating inclined by 21 degrees. Because of the bar thickness the projected slit width is roughly halved to 27 nm, increasing the sensitivity to the trimer size. The peak intensities measured out to the eighth order are evaluated via a few-body scattering theory. The trimer pair distance is found to be (r) = 1.1(+0.4)(-0.5) nm in agreement with predictions for the ground state. No evidence for a significant amount of Efimov trimers is found. Their concentration is estimated to be under 6%, less than expected.The size of the helium trimer is determined by diffracting a beam of 4He clusters from a 100 nm period grating inclined by 21 degrees. Because of the bar thickness the projected slit width is roughly halved to 27 nm, increasing the sensitivity to the trimer size. The peak intensities measured out to the eighth order are evaluated via a few-body scattering theory. The trimer pair distance is found to be (r) = 1.1(+0.4)(-0.5) nm in agreement with predictions for the ground state. No evidence for a significant amount of Efimov trimers is found. Their concentration is estimated to be under 6%, less than expected.

arXiv:quant-ph/0412064Physical Review LettersAug 2, 200578 citations

Small weakly bound boson-fermion

^{4}\mathrm{He}_{m}^{3}\mathrm{He}_{n}

clusters formed in a free jet expansion are identified using nondestructive transmission grating diffraction. The observations confirm the existence of more than 11 very tenuous complexes including the three-body halo molecule

^{4}\mathrm{He}_{2}^{3}\mathrm{He}

and the pseudo-Borromean complex

^{4}\mathrm{He}_{2}^{3}\mathrm{He}_{2}

. Effective cluster formation temperatures, extracted from a sudden freeze model for cluster growth using theoretical binding energies, increase smoothly with cluster size, thereby confirming the calculations with the possible exception of

^{4}\mathrm{He}_{2}^{3}\mathrm{He}_{2}