Characterization of neutral boron-silicon clusters using infrared spectroscopy: The case of Si6B

• Mixed boron/silicon clusters are produced by a new dual target laser ablation cluster source.
• The IR spectrum of Si6B is measured via an infrared-ultraviolet two-color ionization scheme.
• Its structure is determined as distorted pentagonal bipyramid with the B atom at one apex.

Nano-size clusters are of great interest for understanding of fundamental properties and processes relevant for applied materials science such as heterogeneous catalysis. In this study, we present a newly developed dual-target dual-laser ablation source, suitable for the production of binary clusters and their spectroscopic characterization. With the current design, an almost arbitrary mixing ratio can be achieved by altering different parameters such as the laser fluences. Boron and silicon targets are chosen for cluster production, illustrating the possibility to control the outcome ranging from pure boron over mixed SinBm to pure silicon clusters. As a test system, Si6B clusters are characterized by means of infrared-ultraviolet two-color ionization (IR-UV2CI) spectroscopy, combined with quantum chemical simulations. The most stable structure of Si6B (Cs, 2A′) predicted in our previous work is confirmed by the present experiment. Doping of Si7 with a single B atom has a drastic impact on the geometric, vibrational, and electronic properties.

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