1. Mass Spectrometry and Advanced Instrument Group, Korea Basic Science Institute, Ochang Center, Chungbuk 28119, South Korea
2. Department of Chemistry, Sungkyunkwan University, Suwon 16419, South Korea
3. Korea Basic Science Institute, Daejeon 34133, South Korea
4. Division of High Technology Materials Research, Korea Basic Science Institute, Busan Center, Busan 46742, South Korea
5. Department of Physics, University of Konstanz, Konstanz D-78457, Germany