| 概 要 |
Title1
【Different ways to femtosecond imaging and light amplification】
Speaker: Heide Nadda Ibrahim（INRS-EMT, Senior post doctoral fellow）
Abstract:
The first part of the talk will focus on a tabletop multiphoton approach to image two chemical reactions in the acetylene cation. These are proton migration and dissociation along the C-C bond. With this pump-probe approach, based on Coulomb explosion imaging, we have obtained the first high-resolution molecular movie of proton migration in the acetylene cation – an alternative to demanding free-electron-lasers and other VUV light sources when ionizing from the HOMO-1. The challenge was hereby populating the first excited state of the cation, rather than the ground state, as well as its proof. The results show a never before observed to- and fro isomerization behavior between the two isomers acetylene and vinylidene. The experimental results are in excellent agreement with the timescales and relaxation pathways predicted by new and quantitative ab initio trajectory simulations. [arxiv.org/abs/1402.1419, nature comm. accepted.]
The second part of the talk introduces a new mechanism of nonlinear light amplification based in the Fourier plane of a 4-f setup. Today’s ultrafast lasers operate at the physical limits of optical materials to reach extreme performances. Amplification of single-cycle laser pulses with their corresponding octave-spanning spectra still remains a formidable challenge since the universal dilemma of gain narrowing sets limits for both real level pumped amplifiers as well as parametric amplifiers. We demonstrate that employing parametric amplification in the frequency domain rather than in time domain opens up new design opportunities for ultrafast laser science, with the potential to generate single-cycle multi-terawatt pulses. Fundamental restrictions arising from phase mismatch and damage threshold of nonlinear laser crystals are not only circumvented but also exploited to produce a synergy between increased seed spectrum and increased pump energy. This concept was successfully demonstrated by generating carrier envelope phase stable, 1.43 mJ two-cycle pulses at 1.8 mm wavelength. [Schmidt, B. E. et al. Frequency domain optical parametric amplification. Nat. Commun. 5:3643 doi: 10.1038/ncomms4643 (2014).]
Title2
【Deceleration of dissociating molecular wave packets by solvent cage: the dynamic continuum ansatz】
Speaker: Sebastian Thallmair (Ludwig-Maximilians-Universität München, PhD student）
Abstract: 添付ファイルをご覧ください。
title2.pdf
|
