Development of a wideband multilayer grating with a new layer structure for a flat-field spectrometer attached to transmission electron microscopes in the 2-4 keV range, 2

透過型電子顕微鏡に搭載可能な24keV領域用平面結像分光器のための新しい膜構造を持つワイドバンド多層膜回折格子の開発,2

今園 孝志; 倉本 智史*; 小池 雅人

Imazono, Takashi; Kuramoto, Satoshi*; Koike, Masato

透過型電子顕微鏡に搭載できる24keV領域用平面結像分光器を開発するために、一定入射角でも一様に高い回折効率を得ることができる新しい膜構造を持つワイドバンド多層膜回折格子を開発した。これまでのわれわれの研究において、マスタ回折格子にこの新しい膜構造を積層した新型多層膜回折格子の回折効率が測定エネルギー領域全域(2.14.0keV)において広帯域化していることを確かめた。今回、実用性・汎用性を鑑み、新たにマスタ回折格子を作製し、それのレプリカ回折格子に新しい膜構造を積層した多層膜回折格子の回折効率を測定した。測定は前回同様、PFの二結晶ビームラインBL-11Bに接続した自前の軟X線回折計を用いて行った。その結果、レプリカ回折格子の回折効率は高エネルギー側でマスタよりわずかに劣るものの、レプリカで回折効率の広帯域化に成功した。

A soft X-ray spectrograph to attach to transmission electron microscopes has been developed. Original TEM-SXES instruments can detect soft X-ray emission (SXE) spectra of the 60-2000 eV range. However it is necessary to develop a new SXES instrument that covers a wider energy range from 2 keV to 4 keV. Observation of the SXE spectra in this energy range needs a multilayer grating because in which a typical grating with a gold coating is no longer practical. A conventional multilayer grating has high diffraction efficiency but narrow band at a fixed angle of incidence. It indicates that the SXES instrument should employ a mechanism for wavelength scanning to cover the required energy range and is unsuitable for the spectrograph to attach to a TEM. To overcome this problem, a new multilayer structure was invented, which uniformly enhances the reflectivity in a few keV energy range at a fixed angle of incidence. The multilayer was deposited on a laminar varied-line-spacing replica grating. The diffraction efficiency of the multilayer grating was evaluated by a goniometric apparatus, soft X-ray diffractometer, at a double-crystal Si monochromator BL-11B at Photon Factory, KEK. It varies from 0.6% to 2.7% over the whole energy range. This means the wide-band multilayer replica grating was developed successfully.