HIGHLY SENSITIVE PENNING IONIZATION ELECTRON SPECTROSCOPYBY A MAGNETIC BOTTLE ELECTRON ENERGY ANALYZER Hideyasu Tanaka, Ryo Maruyama, Yoshihiro Yamakita, Hideo Yamakado+, Fuminori Misaizu and Koichi Ohno Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki, Aoba-ku, Sendai 980-8578, Japan +Department of Material Science and Chemistry, Faculty of Systems Engineering, Wakayama University, Sakaedani, Wakayama 640-8510, Japan A highly sensitive apparatus for Penning ionization electron spectroscopy has been developed by using magnetic bottle effect. Sensitivity of electron detection is about 103 times higher than a conventional hemispherical analyzer.