Dvorak Matthieu, Müller Markus, Bünermann Oliver, Stienkemeier Frank
Physikalisches Institut, Universität Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany.
Institut für Physikalische Chemie, Georg-August-Universität Tammannstr. 6, 37077 Göttingen, Germany.
J Chem Phys. 2014 Apr 14;140(14):144301. doi: 10.1063/1.4870395.
Complexes made of either Ar(N) or (H2)N clusters (N = 1-170) and a single PTCDA molecule (3,4,9,10-perylene-tetracarboxylic-dianhydride) are assembled inside helium droplets and spectroscopically studied via laser-induced fluorescence spectroscopy. The frequency shift and line-broadening are analyzed as a function of N and of the pick-up order of the PTCDA and cluster material in order to track liquid or solid properties of the clusters. For argon, the solid phase is observed for N > 10 above which the pick-up order dramatically influences the localization of the chromophore with respect to the Ar cluster. If the droplets are doped first with Ar, the chromophore remains on the surface of a solid cluster whereas for the reversed pick-up order the molecule is surrounded by an argon shell. At N < 10 wetting and the formation of the first solvation shell are observed. For para-hydrogen, a transition to the solid is observed at N ~ 20-25, confirming previous theoretical predictions on the existence of a liquid-like phase at such small sizes, even below the bulk hydrogen freezing temperature.
由Ar(N)或(H₂)N团簇（N = 1 - 170）与单个PTCDA分子（3,4,9,10 - 苝四羧酸二酐）组成的复合物在氦液滴内部组装，并通过激光诱导荧光光谱进行光谱研究。分析频率偏移和谱线展宽作为N以及PTCDA和团簇物质拾取顺序的函数，以便追踪团簇的液体或固体性质。对于氩气，当N > 10时观察到固相，在此之上拾取顺序极大地影响发色团相对于Ar团簇的定位。如果液滴首先用Ar掺杂，发色团保留在固体团簇的表面，而对于相反的拾取顺序，分子被氩壳包围。在N < 10时，观察到润湿和第一溶剂化壳的形成。对于对氢，在N ~ 20 - 25时观察到向固体的转变，证实了先前关于在如此小尺寸下存在类似液相的理论预测，甚至低于体相氢的凝固温度。
