Ono, M. Kikuchi, T. Mase, K. Masuda, Y. Nakayama, Y. Ohno, S. Ozawa, K. Sato, Y. Yoshikawa, I. Yoshioka, K. JACoW Publishing Geneva, Switzerland 2673-5520 978-3-95450-229-5 10.18429/JACoW-MEDSI2020-TUPA01 English 119-122 vacuum site quadrupole synchrotron-radiation synchrotron Contribution to a conference proceedings 2021 2021-10 https://doi.org/10.18429/JACoW-MEDSI2020-TUPA01 https://jacow.org/medsi2020/papers/tupa01.pdf Although nonevaporable getter (NEG) pumps are widely used in synchrotron radiation facilities, pure metal Titanium (Ti) has not been used as a NEG because the activation temperature of a Ti thin film deposited by DC magnetron sputtering was reported to be 350-400 °C*. Recently Miyazawa et al. found that high-purity Ti deposited under ultra-high vacuum (UHV) followed by N₂ introduction works as a NEG with an activation temperature of 185 °C**,***. Since the concentration of impurities such as O, C, and N in the Ti thin film prepared by this method is 0.05% or less, we named this as oxygen-free Ti. In this study, we evaluated the pumping properties of oxygen-free Ti thin films after high-purity N₂ introduction by total and partial pressure measurements. A vacuum vessel with oxygen-free Ti deposited on the inner walls was found to pump H₂, H₂O, O₂, CO and CO₂ even after 30 cycles of high purity N₂ introduction, air exposure, pumping, and baking at 185 °C. Furthermore, we analyzed the oxygen-free Ti thin films after high-purity N₂ or air introduction by synchrotron radiation X-ray photoelectron spectroscopy. The results show that more TiN was formed when high-purity N₂ was introduced after oxygen-free Ti deposition. High purity of the Ti thin film and TiN formation on the surface seem to be responsible for the reduced activation temperature as low as 185 °C.