<title>Zero kinetic energy photoelectron spectroscopy and femtosecond dynamics of the cluster Na3</title>

Abstract

Zero kinetic energy (ZEKE) photoelectron spectroscopy has been employed to study the spectroscopy and the geometry of the sodium cluster Na<SUB>3</SUB><SUP>+</SUP> with nanosecond tunable dye lasers. The fully resolved cation vibrational spectra prove the equilateral (D<SUB>3h</SUB>) geometry of Na<SUB>3</SUB><SUP>+</SUP>. Due to the high resolution of the ZEKE method we derived a much improved value for the ionization potential of Na<SUB>3</SUB> of 31,363 +/- 5 cm<SUP>-1</SUP>, which is about 300 cm<SUP>-1</SUP> lower than previous values. The real- time dynamics of two photon ionization and fragmentation of Na<SUB>3</SUB> has been studied applying femtosecond pump-probe techniques in combination with ion- and ZEKE photoelectron spectroscopy. Three dimensional vibrational wave packet motions in the excited state B and in the ground state X as well as pseudorotational wave packet motion in the B-state have been observed. Time resolved fragmentation studies show ultrafast picosecond decays of most of the excited states of Na<SUB>3</SUB>.