Author Institution: Institute of Radio Astronomy of NASU, Chervonopraporna 4, 61002 Kharkov, Ukraine; Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 107, Taiwan; now: Department of Nature Science, Taipei Municipal University of Education, Taipei, Taiwan; Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 107, Taiwan; Optical Technology Division, NIST, Gaithersburg, MD 20899-8441, USA; Chemical Sciences and Technology Laboratory, NIST, Gaithersburg, MD 20899; now: Rohm and Haas Co., Spring House, PA 19477