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CIPE Home Exchanges and Programs International Exchange Activities Institutional Program for Young Researcher Overseas Visits Reports by Researchers HAMONOU Linda


Department & title:
Researcher, Dept. of Engineering Science
Kansas State University
From 14 AUG. 2010 to 15 OCT. 2010

Research theme:Siegert-state method for strong field ionization of molecules

Summary of research activities during your overseas visit

During my stay at Kansas state university, my research work under Professor Toru Morishita’s supervision has been divided into two principal activities.

The first purpose of my work was to complete the programming work which I started at my arrival in Japan in February 2010. That is to develop a method able to calculate energies and ionization rates for the states of diatomic molecules placed in an electric field using molecules modeled by potential, Discrete Variable Representation method, and R-matrix propagation techniques. The method has been developed for H2+ allowing us to obtain accurate energies and ionization rates for Siegert states.

The second purpose of my work was to use other theoretical approaches to compare and verify the validity of the energies and ionization rates obtained with our new approach. That for, I choose to use two well established theories. A method bases on perturbation theory was developed to allow the comparison of the energies obtained and Molecular ADK theory was used to obtain ionization rates for comparison.

Perturbation theory has been widely used it atomic and molecular physics to obtain a first approximation of states’ energies, however its accuracy is limited to low electric field so that more complex methods need to be implemented. The perturbation theory method developed enabled us to verify the accuracy of our results for low electric field. Molecular ADK theory is also limited to a certain range of electric field and its behavior is well known, using the code provided by the group at Kansas state university allowed us to verified the validity of the ionization rates obtained by our new method.

Research outcome obtained

The work accomplished at Kansas state university allowed me to complete the initial part of my programming research started in Japan. That is to develop a computer code able to obtain ionization rates and energies for molecular Siegert state. The first energies and ionization rates were obtained for molecular H2+ modeled by a rounded potential wells. We obtained initial energies and ionization rates for the ground stated and the two first excited states of H2+ and were able to compare them with other theoretical results to verify their accuracies. The initial results obtained allowed us to open new discussions on the following steps to follow in the research process, to solve several problems in the program and to plan the next steps to be used to test the program from an accuracy and an optimization of efficiency point of view as well as the use of better potential to model the molecules.

We were also able to use other theoretical methods such as a perturbation theory code and a Molecular ADK code. This not only allowed the comparison of the results to test the accuracy but also leaded to a new opening toward the understanding of the molecular physical processes in strong laser field. I attended weekly group meeting organized by Prof. C. D. Lin. and gave a presentation and had discussions with participants. The exchange permitted to open the discussion on the extension of the code toward other molecules and to have an overview of the data already available in the field for comparison as well as to overview the need for further developments of our techniques.

Reflection and suggestion on the program, particularly from the viewpoint of internationalization of researchers and students.

The exchange opened new perspectives for the research topic as it allowed to meet with people having different backgrounds and knowledge. It also allowed speeding up the development of the computer code by exchanging ideas.

The exchange also permitted me to discover a new country as it was my first experience of staying in the US for such an amount of time and especially my first time in Kansas. It allowed me to extend my knowledge of the American culture and to discover the specialties of Kansas such as cuisine, life style and national park.

Created: October 15, 2010 / Last modified:November 15, 2012