Reconsideration of atomic scattering factor for ultrafast electron diffraction

2015 Fiscal Year Final Research Report

• Project/Area Number: 26790049
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Thin film/Surface and interfacial physical properties
• Research Institution: Hokkaido University
• Principal Investigator: Naruse Nobuyasu 北海道大学, 高等教育推進機構, 特任助教 (30350408)
• Project Period (FY): 2014-04-01 – 2016-03-31
• Keywords: 超高速時間分解電子顕微鏡 / 光励起物性 / 貴金属 / 溶融過程 / 相対論的電子パルス / 原子間ポテンシャル / 原子散乱因子 / レーザー光

Outline of Final Research Achievements

When a strong laser light is concentrated to matters, a melting occurs. The melting has been considered to be the effect of heat by the laser absorption (thermal melting). Recently, some papers have reported that the melting in the case of semiconductors occurs much earlier than believed thermal melting. The reason is explained below: the melting is promoted by the excited electrons, in the material atoms, which led to the weakened binding with atoms (non-thermal melting). It means that the spatial distribution of charge in the atoms is changing momentarily following the laser irradiation. We have experimentally observed ultrafast melting process (femto-second order) for gold, a representative metal. Thus, the non-thermal melting mechanism is applicable to the metal from the theoretical study.

Free Research Field

光物性、表面、透過電子顕微鏡