Photodepletion spectroscopy and predissociation of the Na3 A′(2A1′) state

The A′(2A1′) ← X(2E′) system of the sodium trimer Na3 was studied by photodepletion in a supersonic molecular beam, in which the ion signal of Na3+ generated by one-photon ionization of Na3 (X 2E′) with an excimer laser decreased when an excimer-pumped dye laser was also applied prior to the ionizing laser to excite the neutral Na3 from the X 2E′ ground state to the A′ state. Photodepletion spectra were recorded in the wavelength range 700–780 nm with a spectral resolution of 7.5 GHz of the pulsed dye laser. The strongest depletion was found at wavelengths around 740 nm with a measured depletion cross-section of about 1.2 Å2. Structures with typical widths between 10 and 30 cm−1 were observed in the photodepletion spectra and are attributed to vibronic bands in the A′ state.