Observation of free-electron-laser-induced collective spontaneous emission in soft x-ray region

2016 Fiscal Year Final Research Report

• Project/Area Number: 26286080
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Quantum beam science
• Research Institution: Institute for Molecular Science
• Principal Investigator: SHIGEMASA Eiji 分子科学研究所, 極端紫外光研究施設, 准教授 (90226118)
• Co-Investigator(Kenkyū-buntansha): 小杉 信博 分子科学研究所, 光分子科学研究領域, 教授 (20153546)
• Co-Investigator(Renkei-kenkyūsha): IWAYAMA Hiroshi 分子科学研究所, 極端紫外光研究施設, 助教 (50584570)
• Research Collaborator: Harries J. R. ; FUJISE Hikaru ; KUMA Susumu ; TAMASAKU Kenji
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: 超蛍光 / 軟X線 / 自由電子レーザー / 極端紫外光

Outline of Final Research Achievements

In order to observe collective spontaneous emission (SF) in the short wavelength region, we have developed a new fluorescence spectrometer. Experiments have been carried out at BL1 of SACLA (X-ray free electron laser (FEL) facility) by using this spectrometer, which was set at the downstream of the beamline, for observing EUV radiation from excited helium atoms. The FEL wavelengths were set at 53.7 nm and 52.2 nm, which correspond to the 3p and 4p resonances.
We have observed intense EUV radiation from excited helium atoms, emitted to the downstream of the beamline. At the both wavelengths, pulsed time structures for the radiation were observed, whose widths and delay times depend on the sample gas pressures. These trends agree with the general features of SF, but the pressure dependence of the peak intensity completely differs from what is expected for the SF. This may be due to the insufficient time resolution. A further work with much improved time resolution is scheduled.

Free Research Field

原子分子物理