| Grant number: | 16/20886-1 |
| Support type: | Regular Research Grants |
| Duration: | March 01, 2017 - February 28, 2019 |
| Field of knowledge: | Physical Sciences and Mathematics - Physics - Condensed Matter Physics |
| Principal researcher: | Leonardo de Boni |
| Grantee: | Leonardo de Boni |
| Home Institution: | Instituto de Física de São Carlos (IFSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil |
Abstract
The research will be developed in this period is related to the development and modernization of an ultrafast spectroscopy laboratory, which will, in the near future, create the possibility of ultrafast temporal dynamics studies in different materials, such as organic molecules and inorganic compounds. In addition to these initial Femtochemistry studies, it is intended in the future to use such experimental framework for the study of biological materials such as proteins and DNA, which require the use of polarization control in ultrafast lasers employed on the spectroscopic techniques. The main objective will be the development and modernization of the ultrafast spectroscopy techniques at transmittance mode (transient absorption) and adapting it to the study of chiral materials and possibly metamaterials. The techniques and their adaptations require optical and mechanical components extremely accurate and reliable, which must be purchased with the approval of this project. In these coming years, the research project will be associated with the assembly and to obtain significant results in Femtochemistry area of organic materials with great importance for the basic knowledge in the area and high relevance to application technology.The study of population dynamics employing polarization control of the excitation and probe fields can provide important information about molecules and its excited states and how chiral structures behave in their higher excited electronic states. In such states or energy bands, the interaction with the light can bring important information to the understanding of secondary structures of chiral molecules (DNA, amino acids, etc.). Based on this, in the opportunity to observe how effects due to chirality can behave in ultrafast time (hundreds of femtoseconds to tens of picoseconds), in this project, in addition to modernizing the transient absorption technique (excitation and probe), polarization control of the optical fields will be adapted (linearly polarized, circularly polarized left and right) for a wide spectral range (VIS-NIR). After the implementation of such technique, it will be used to characterize and quantify the nonlinear effects in known organic materials, which may have polarization dependency of light. This initial part will improve considerable the available and obsolete technique in the Photonics Group. The technique is limited in time and spectral resolution due to the optical and mechanical components already old and faulty, which reduces the reliability of the technique. The improvement and modernization of the techniques will make ultrafast spectroscopy line competitive with other researchers groups. It is important also to emphasize here that the second stage of the project, which take into account the polarization control, will turn the transient absorption technique sensitive to circular dichroism in excited states of chiral materials. It can be stated, with certainty, that techniques which study circular dichroism of excited state and its dynamics are very few, which makes this field of research something quite promising for the generation of basic concepts and open up new areas of research. This experimental technique will be applied to the understanding of basic chiral materials as simple organic molecules and chiral polymers and may be the beginning of the use of it to understand more complex molecules such as DNA, proteins, etc. (AU)
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