Vibrational states of atomic hydrogen in bulk and nanocrystalline palladium studied by neutron spectroscopy. - Maiko Kofu; Naoki Hashimoto; Hiroshi Akiba; Hirokazu Kobayashi; Hiroshi Kitagawa; Kazuki Iida; Mitsutaka Nakamura; Osamu Yamamuro (Physical Review B, 2017)