概 要 |
Stockholm University(Prof. Mats Larsson 研)から二人の研究者をお迎えしてオープンセミナーを開催致します。皆様の参加をお待ちしております。
Speaker1:
Sviatlana Viarbitskaya
Title:
Resonance-enhanced Second Harmonic Generation from spherical microparticles in aqueous solution
Abstract
Second harmonic generation (SHG) is a nonlinear optical effect sensitive to interfaces between materials with inversion symmetry. The scattered second harmonic intensity from surfaces of suspended microparticles, i.e. micron-sized particles, is characterized by its complex angular distribution dependence on the shape, size, and physical and chemical properties of the molecules making up the outer layer of the particles. In particular, the overall scattered second harmonic intensity has also been predicted to have a dramatic and nontrivial dependence on the particle size.
It is shown that second harmonic generation from the microparticle surfaces is indeed observed and the experimental conditions for measuring its intensity dependence on the particle size, such as light collection solid angle, are discussed. Data are presented that show qualitatively the predicted changes of the second harmonic intensity on microparticle diameters over the range of 0.9-3.0 m. The constructed apparatus is shown to be also capable of detecting second harmonic generation from single microparticle.
Speaker2:
Dr. Anneli Ehlerding
Title:
Electron-Ion Recombination in Atmospheric and Laboratory Plasmas.
Abstract:
The storage ring CRYRING, Stockholm, Sweden, is used to measure dissociative recombination with molecular ions, which is the process where a positive ion recombines with an electron to form neutral fragments. This process is important in most plasma environments, atmospheric and interstellar as well as artificial (eg. plasma-assisted combustion, fusion reactor erosion) as it provides a terminating step in the molecular formation and a way to produce radicals. For instance the dominance of CO2+ in the atmosphere of Venus and Mars makes the recombination of this ion important in modeling the carbon abundance and the escape flux in these environments.
I will talk about the storage ring technique we use to perform experiments and discuss the background and outcome of the studies.
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