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Abstract

We report on rotationally resolved laser induced fluorescence (LIF) and vibrationally resolved resonance enhanced multiphoton ionization (REMPI) spectroscopy of the chiral molecule 1-indanol. Spectra of the S₁ ← S₀ electronic transition are recorded in a jet-cooled, pulsed molecular beam. Using two time-delayed pulsed lasers, the lifetime of the S₁ state of the two most stable conformers, referred to as eq1 and ax2, is determined. The S₁ ← S₀ origin bands of these conformers as well as the transition to a vibrationally excited level in the S₁ state of eq1 are recorded with full rotational resolution (25 MHz observed linewidth) by measuring the LIF intensity following excitation with a tuneable, narrowband cw laser. On selected rotationally resolved electronic transitions, Lamb-dips are measured to confirm the Lorentzian lifetime-contribution to the observed lineshapes. The rotationally resolved S₁ ← S₀ origin band of a Neon-complex of eq1 is measured via LIF as well. The fit of the rotationally resolved LIF spectra of the origin bands to those of an asymmetric rotor yields a standard deviation of about 6 MHz. The resulting spectroscopic parameters are tabulated and compared to the outcome of ab initio calculations. For both conformers as well as for the Ne-eq1 complex, the geometric structures in the S₀ and S₁ states are discussed. For all systems, the transition dipole moment is mainly along the long axis, the a-axis, the contributions along the b- and c-axes being about one order of magnitude smaller.