Spectroscopy of 3, 4, 9, 10-perylenetetracarboxylic dianhydride (PTCDA) attached to rare gas samples: clusters vs. bulk matrices. II. Fluorescence emission spectroscopy.

The interaction between 3, 4, 9, 10-perylenetetracarboxylic dianhydride (PTCDA) molecules and solid rare gas samples is studied by means of fluorescence emission spectroscopy. Laser-excited PTCDA-doped large argon, neon, and para-hydrogen clusters along with PTCDA embedded in helium nanodroplets are spectroscopically characterized with respect to line broadening and shifting. A fast non-radiative relaxation is observed before a radiative decay in the electronic ground state takes place.

Spectroscopy of 3, 4, 9, 10-perylenetetracarboxylic dianhydride (PTCDA) attached to rare gas samples: clusters vs. bulk matrices. I. Absorption spectroscopy.

The interaction between 3, 4, 9, 10-perylenetetracarboxylic dianhydride (PTCDA) and rare gas or para-hydrogen samples is studied by means of laser-induced fluorescence excitation spectroscopy. The comparison between spectra of PTCDA embedded in a neon matrix and spectra attached to large neon clusters shows that these large organic molecules reside on the surface of the clusters when doped by the pick-up technique. PTCDA molecules can adopt different conformations when attached to argon, neon, and para-hydrogen clusters which implies that the surface of such clusters has a well-defined structure without liquid or fluxional properties.

Efficient trapping of silver cations in a rare gas matrix: Ag3+ in argon.

Mass selected cations of Ag clusters are deposited, together with Ar seeded with CO2 (or other electron scavengers such as O2, N2O, or CCl4), on a cold substrate, while being flooded with low energy electrons. Optical absorption measurements reveal an efficient trapping of Ag cluster cations in the Ar matrix, provided that CO2 or another electron scavenger is present to ensure charge neutrality of the matrix. The spectrum of Ag3+ thus obtained is in excellent agreement with previous predictions from quantum chemical calculations.