Electronic spectroscopy of anthracene molecules trapped in helium nanodroplets

The electronic spectroscopy of anthracene trapped in liquid helium nanodroplets has been studied in the spectral region of the S1 ← S0 transition using both laser-induced fluorescence and molecular beam depletion spectroscopy with mass spectrometric detection. The absorption band has been located at 27 625.9 cm−1, red-shifted by 61.4 cm−1 from the respective gas phase transition. It consists of two well separated maxima and a long tail to the blue side which is essentially assigned to the phonon wing. The origin of the band structure is discussed in this Letter.