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Article
Title	Vibrational Excitation of Ammonia Molecules by FEL-SUT
Author(s)	Ogi, Yoshihiro ; Tsukiyama, Koichi
Affiliation	(TUS-Kagurazaka, Shinjuku, Tokyo)
Publication	2004
In:	26th International Free Electron Laser Conference and 11th FEL User Workshop 2004, Trieste, Italy, 29 Aug - 3 Sep 2004, pp.e-proc. THPOS26
Subject category	Accelerators and Storage Rings
Abstract	Free Electron Laser at Tokyo University of Science (FEL-SUT) was employed for exciting single vibrational modes of ammonia molecules. FEL is tuned to 10.5 &mu;m, corresponding to the X<sup>1</sup>A<sub>1</sub>' (&nu;<sub>2</sub> = 1) &larr; (&nu;<sub>2</sub> = 0) transition of NH<sub>3</sub>. The population of the vibrationally excited states is probed by the (2 + 1) resonance enhanced multiphoton ionization (REMPI) technique via the B <sup>1</sup>E" Rydberg state. Maximum excitation efficiency of &nu;<sub>2</sub> = 1 &larr; &nu;<sub>2</sub> = 0 transition was about 50 %, which was estimated by taking account of Franck-Condon factors and the rotational line strengths. Rotational analyses of the spectra revealed that vibrational ladder climbing up to &nu;<sub>2</sub> = 2 in NH<sub>3</sub> was realized for the first time. Experimental results on &nu;<sub>4</sub> vibrational excitation of NH<sub>3</sub> and ND<sub>3</sub> will be also reported.