There is no general picture to describe the influences of reagent rotational excitation on the reaction,which proceeds via the tunnelling mechanism at collision energies far below the reaction barrier.Here we report a...There is no general picture to describe the influences of reagent rotational excitation on the reaction,which proceeds via the tunnelling mechanism at collision energies far below the reaction barrier.Here we report a crossed beam study on the prototypical reaction of F+D_(2)(v=0,j=0,1)→DF(v′)+D at collision energies between 44 and 164 cm^(-1)with the scheme of multichannel D-atom Rydberg tagging time-of-flight detection.Vibrational state resolved differential cross sections are obtained at v′=2,3,4 levels.The effects of reagent rotational excitation were investigated at an equivalent amount of total energy by precise tuning of translational energies.Compared with translation,the rotation of D_(2) is found to be more efficient to promote the title reaction.Profound differences introduced by rotation of D_(2) are also observed on the angular distribution and quantum state distribution of DF products.We hope the present work could provide an example for understanding the effects of reagent rotational excitation on the chemical reaction at energies that are much lower than the reaction barrier.展开更多
The prototypical reaction of F+HD→DF+H was investigated at collision energies from 3.03 meV to 17.97 meV using a crossed molecular beam apparatus with multichannel Rydberg tagging time-of-flight detection.Significant...The prototypical reaction of F+HD→DF+H was investigated at collision energies from 3.03 meV to 17.97 meV using a crossed molecular beam apparatus with multichannel Rydberg tagging time-of-flight detection.Significant contributions from both the BornOppenheimer(BO)forbidden reaction F^(*)(^(2)P_(1/2))+HD→DF+H and the BO-allowed reaction F(^(2)P_(3/2))+HD→DF+H were observed.In the backward scattering direction,the contribution from the BO-forbidden reaction F^(*)(^(2)P_(1/2))+HD was found to be considerably greater than the BO-allowed reaction F(^(2)P_(3/2))+HD,indicating the non-adiabatic effects play an important role in the dynamics of the title reaction at low collision energies.Collision-energy dependence of differential cross sections(DCSs)in the backward scattering direction was found to be monotonously decreased as the collision energy decreases,which does not support the existence of resonance states in this energy range.DCSs of both BO-allowed and BO-forbidden reactions were measured at seven collision energies from 3.03 meV to 17.97 meV.It is quite unexpected that the angular distribution gradually shifts from backward to sideway as the collision energy decreases from 17.97 meV to 3.03 meV,suggesting some unknown mechanisms may exist at low collision energies.展开更多
A new fuelling method, the supersonic molecular beam injection (SMBI) system has been applied to W7-AS in May 2001,supported by the National Nature Science Foundation of China and the Max-Planck Institute of Plasma Ph...A new fuelling method, the supersonic molecular beam injection (SMBI) system has been applied to W7-AS in May 2001,supported by the National Nature Science Foundation of China and the Max-Planck Institute of Plasma Physics, Garching, Germany. The experiments with hydrogen or deuterium on W7-AS were implemented for two years.展开更多
The search for Majorana fermions in topological superconductors is one of paramount research targets in physics today. Using a cryogenic scanning tunneling microscopy, we here report the signature of topologically non...The search for Majorana fermions in topological superconductors is one of paramount research targets in physics today. Using a cryogenic scanning tunneling microscopy, we here report the signature of topologically nontrivial superconductivity on a single material of β-Bi_2Pd films grown by molecular beam epitaxy. The superconducting gap associated with spinless odd-parity pairing opens on the surface and appears much larger than the bulk one due to the Dirac-fermion enhanced parity mixing of surface pair potential. Zero bias conductance peaks, probably from Majorana zero modes supported by such superconducting states, are identified at magnetic vortices. The superconductivity exhibits resistance to nonmagnetic defects, characteristic of time-reversal-invariant topological superconductors. Our study reveals β-Bi_2Pd as a prime platform to generate, manipulate and braid Majorana zero modes for quantum computation.展开更多
基金supported by the National Natural Science Foundation of China(No.21822305,No.21688102,No.22003067)the Chinese Academy of Sciences(No.XDB17000000)。
文摘There is no general picture to describe the influences of reagent rotational excitation on the reaction,which proceeds via the tunnelling mechanism at collision energies far below the reaction barrier.Here we report a crossed beam study on the prototypical reaction of F+D_(2)(v=0,j=0,1)→DF(v′)+D at collision energies between 44 and 164 cm^(-1)with the scheme of multichannel D-atom Rydberg tagging time-of-flight detection.Vibrational state resolved differential cross sections are obtained at v′=2,3,4 levels.The effects of reagent rotational excitation were investigated at an equivalent amount of total energy by precise tuning of translational energies.Compared with translation,the rotation of D_(2) is found to be more efficient to promote the title reaction.Profound differences introduced by rotation of D_(2) are also observed on the angular distribution and quantum state distribution of DF products.We hope the present work could provide an example for understanding the effects of reagent rotational excitation on the chemical reaction at energies that are much lower than the reaction barrier.
基金supported by the National Natural Science Foundation of China(No.21822305,No.21688102,No.22003067)the Chinese Academy of Sciences(No.XDB17000000)。
文摘The prototypical reaction of F+HD→DF+H was investigated at collision energies from 3.03 meV to 17.97 meV using a crossed molecular beam apparatus with multichannel Rydberg tagging time-of-flight detection.Significant contributions from both the BornOppenheimer(BO)forbidden reaction F^(*)(^(2)P_(1/2))+HD→DF+H and the BO-allowed reaction F(^(2)P_(3/2))+HD→DF+H were observed.In the backward scattering direction,the contribution from the BO-forbidden reaction F^(*)(^(2)P_(1/2))+HD was found to be considerably greater than the BO-allowed reaction F(^(2)P_(3/2))+HD,indicating the non-adiabatic effects play an important role in the dynamics of the title reaction at low collision energies.Collision-energy dependence of differential cross sections(DCSs)in the backward scattering direction was found to be monotonously decreased as the collision energy decreases,which does not support the existence of resonance states in this energy range.DCSs of both BO-allowed and BO-forbidden reactions were measured at seven collision energies from 3.03 meV to 17.97 meV.It is quite unexpected that the angular distribution gradually shifts from backward to sideway as the collision energy decreases from 17.97 meV to 3.03 meV,suggesting some unknown mechanisms may exist at low collision energies.
文摘A new fuelling method, the supersonic molecular beam injection (SMBI) system has been applied to W7-AS in May 2001,supported by the National Nature Science Foundation of China and the Max-Planck Institute of Plasma Physics, Garching, Germany. The experiments with hydrogen or deuterium on W7-AS were implemented for two years.
基金financially supported by the National Natural Science Foundation of ChinaMinistry of Science and Technology+2 种基金Ministry of Education of Chinasupports from the National Thousand-Young-Talents Programthe Tsinghua University Initiative Scientific Research Program
文摘The search for Majorana fermions in topological superconductors is one of paramount research targets in physics today. Using a cryogenic scanning tunneling microscopy, we here report the signature of topologically nontrivial superconductivity on a single material of β-Bi_2Pd films grown by molecular beam epitaxy. The superconducting gap associated with spinless odd-parity pairing opens on the surface and appears much larger than the bulk one due to the Dirac-fermion enhanced parity mixing of surface pair potential. Zero bias conductance peaks, probably from Majorana zero modes supported by such superconducting states, are identified at magnetic vortices. The superconductivity exhibits resistance to nonmagnetic defects, characteristic of time-reversal-invariant topological superconductors. Our study reveals β-Bi_2Pd as a prime platform to generate, manipulate and braid Majorana zero modes for quantum computation.
