Pump–probe study of the reconstruction of helium surrounding a tetracene molecule inside a helium droplet

Abstract

The electronic spectra of single tetracene molecules and tetracene–Ar complexes embedded in large (≃10³–10⁴) superfluid helium droplets have been investigated with a pump–probe technique. New sharp (δν≈0.5 cm⁻¹) red-shifted (Δν≈1–2 cm⁻¹) features are obtained in the probe laser spectra indicating a rapid (Δt<20 ns) reconstruction of the He environment upon electronic excitation. These new structures are interpreted with a simple modified bubble-like model. Evidence for a rise in the droplet temperature induced by the pump laser pulse is obtained from a broadening of the phonon wing measured by the probe laser.