Journal Article

PUBDB-2024-05172

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Probing the structure and dynamics of the heterocyclic PAH xanthene and its water complexes with infrared and microwave spectroscopy

Loru, D. (Corresponding author)Extern*DESY* ; Sun, W.DESY* ; Nootebos, H. ; Steber, A. L. ; Ferrari, P. ; Schnell, M.CFEL*DESY*

2024
RSC Publ. Cambridge

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Please use a persistent id in citations: doi:10.1039/D4CP03030C  doi:10.3204/PUBDB-2024-05172

Abstract: To assess the presence of oxygen-containing polycyclic aromatic hydrocarbons (OPAHs) in the interstellar medium and understand how water aggregates on an OPAH surface, we present a comprehensive gas-phase spectroscopy investigation of the OPAH xanthene (C$_{13}$H$_{10}$O) and its complexes with water using IR-UV ion dip spectroscopy and chirped-pulse Fourier transform microwave spectroscopy. The far-infrared spectrum of xanthene shows weak features at 3.42, 3.43, and 3.47 $\mu$m, which have been suggested to partly originate from vibrational modes of PAHs containing sp$^{3}$ hybridized carbon atoms, in agreement with the molecular structure of xanthene. The high resolution of rotational spectroscopy reveals a tunneling splitting of the rotational transitions, which can be explained with an out-of-plane bending motion of the two lateral benzene rings of xanthene. The nature of the tunnelling motion is elucidated by observing a similar splitting pattern in the rotational transitions of the singly-substituted $^{13}$C isotopologues. The rotational spectroscopy investigation is extended to hydrates of xanthene with up to four water molecules. Different xanthene-water binding motifs are observed based on the degree of hydration, with O-H $\cdots\pi$ interactions becoming preferred over O-H $\cdots$O$_\mathrm{xanthene}$ interactions as the degree of hydration increases. A structural comparison with water complexes of related molecular systems highlights the impact of the substrate's shape and chemical composition on the arrangement of the surrounding water molecules.

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Contributing Institute(s):

1. Spectroscopy of molecular processes (FS-SMP)
2. MPSD (CFEL-SDCCM)

Research Program(s):

1. 631 - Matter – Dynamics, Mechanisms and Control (POF4-631) (POF4-631)

Experiment(s):

1. No specific instrument

Appears in the scientific report 2024

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Database coverage:
; ; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Essential Science Indicators ; IF < 5 ; JCR ; National-Konsortium ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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