Preface
The Synchrotron Radiation Laboratory (SRL) of the Institute for Solid State Physics (ISSP)
has been cooperating with the Synchrotron Radiation Research Organization of theUniversity of Tokyo to operate the BL07LSU soft X-ray beamline and its experimental end
stations at SPring-8 since 2006. The beamline has a 27-m-long polarization-controlled
undulator and monochromator covering the photon energy range from 250 eV to 2 keV, withan average photon flux of 1012 photons/s. Since 2009, the SRL staff has been playing anessential role in promoting the ISSP’s joint research program for domestic and international
users of the BL07LSU. The three end stations—ambient pressure X-ray photoemission
spectroscopy, three dimensional nanoESCA, and the high-resolution soft X-ray emission
spectroscopy stations—have excellent ability to operate under high pressure (~20 mbar), highspatial resolution (~70 nm), and high energy resolution (E/E≈10,000), respectively. During
FY2021, as the COVID-19 pandemic persisted, we conducted joint research experiments
while applying infection control measures in accordance with the SPring-8 facility policy. Allof the experiments were carried out as scheduled, except for those involving the internationaluser groups, who could not come to Japan. We thus conducted the experiments on their behalf
via remote connection.
To utilize the characteristics of BL07LSU, new challenges were undertaken, including thefirst observation of rotational X-ray magnetic linear dichroism (XMLD), which is a soft X-ray
magneto-optical measurement during rotation of the angle of the linearly polarized beam andthe X-ray magneto-optical Kerr effect when utilizing polarization switching. A soft X-ray
XAFS imaging experiment has been launched using a 50 nm focused beam produced by aWalter-type soft X-ray focusing mirror system. This experiment serves as both research anddevelopment for the next-generation synchrotron radiation facility in Sendai and a way to takeadvantage of the characteristics of BL07LSU. A high-resolution soft X-ray charge-coupleddevice detector has been introduced for soft X-ray emission spectroscopy to obtain aresolution of E/E > 10000. The ambient-pressure photoemission spectroscopy system has
also been improved to increase the measurement pressure to 100 Torr. All of these
improvements were made as part of research and development for the upcoming synchrotron
radiation facility. We have also expanded our activities to include the time-resolved soft X-ray
magneto-optical effect and nonlinear spectroscopy experiments using a focused beam ofseveral hundred nanometers at the X-ray free electron laser facility SACLA.
The SRL will terminate the joint research program at SPring-8 in the first half of 2022 andtransfer most of the instruments to the new facility. In addition, SRL will continue to develop
a novel soft X-ray imaging system that can most effectively make use of the new light source.
In addition to the cutting-edge activities using synchrotron radiation and SACLA, the SRL
has promoted the scientific use of laser-based high-harmonic generation in the vacuum
ultraviolet and soft X-ray regions at the Kashiwa campus. Since 2015, the SRL has operated ajoint research program of the high-resolution laser spin- and angle-resolved photoelectronspectroscopy (SARPES) system, which is designed to provide high-energy (1.7 meV) and angular resolutions with high-efficiency spin detectors for various types of solids, such as spinorbit coupled materials and ferromagnetic materials.
Our goal is to provide users with a platform that uses both synchrotron radiation and highharmonic laser generation through strong collaboration with other LASOR group members.

June 30, 2022
Yoshihisa Harada
Director of SRL-ISSP