2017 Fiscal Year Research-status Report
Ultrafast dynamics and resonance effects in photoemission from surfaces
| Project/Area Number |
16K05393
|
|---|
| Research Institution | Chiba University |
|---|
Principal Investigator |
KRUEGER PETER 千葉大学, 大学院工学研究院, 教授 (30706362)
|
|---|
| Project Period (FY) |
2016-04-01 – 2020-03-31
|
| Keywords | 光物性 / 表面・界面 |
|---|
| Outline of Annual Research Achievements |
(1) In this year we have completed the analysis of the one-dimensional model of time-delay in photoemission, where a wave packet is multiply scattered at a sequence of potential barriers. The time-delay was calculated in 3 ways: (i) by solving the time-dependent Schroedinger equation (ii) by using stationary multiple scattering for a plane-wave and (iii) for a wave packet via Fourier analysis. We found that (iii) gives the same time delays as direct wave packet simulation (i). This is important because it shows that multiple scattering theory can be used to obtain accurate photoemission time-delay in crystals. Method (ii) is reliable only when the wave packet width is much larger than the barrier width and spacing.In general the wave packet has to be reconstructed from the plane-wave multiple scattering calculations using (iii). These results have been presented at a conference. Also, the collaboration with Zurich on time-delay from Cu(111) has been published. [Optica 4 (2017) 1492]
(2) On the theory of non-resonant ARPES, we have started developing a
new method from supercell DFT band structure codes.The main challenge is the construction of final states with the proper (non-periodic) ARPES boundary conditions from the band structure eigenstates (which satisfy periodic boundary conditions). To this end we have developed a matching method between
the band states and the free electron states. We have applied this
method to a one-dimensional model and have obtained very good results.
They have been presented as a paper [eJSSNT 16 (2018) 49] and at 2 conferences.
|
| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
Most objectives of the 2nd year have been met.
(1) Very good progress has been made for the photoemission time delay
problem. The one-dimensional case has been solved. The results are very important. The analysis shows that our approach is successful:
photoemission time delay can be computed using multiple scattering
theory which is much more efficient than brute force time-dependent simulations.
(2) On non-resonant ARPES theory we have made very good progress. However the combination of multiplet theory with multiple scattering for the calculation of resonant Auger electron diffraction takes a bit longer than expected.
|
| Strategy for Future Research Activity |
During the next year the following plan will be carried out.
(1) Ultrafast photoelectron dynamics: The theory of time delay from multiple scattering calculations that we have developed in one-dimension, will be generalized to the three-dimensional case.
(2) Non-resonant ARPES theory: The matching method between supercell band states and free waves that we have developed in a 1-D model will be generalized 3 dimensions and wave functions from a DFT code.
Resonant Auger electron theory: The combination of multiplet theory with multiple scattering for the calculation of resonant Auger electron diffraction will be pushed ahead.
|
| Causes of Carryover |
The costs for repairing one workstation turned out to be less than expected.
|
