title: Multiple Rabi Splittings under Ultrastrong Vibrational Coupling.
abstract: From the high vibrational dipolar strength offered by molecular liquids, we demonstrate that a molecular vibration can be ultrastrongly coupled to multiple IR cavity modes, with Rabi splittings reaching 24% of the vibration frequencies. As a proof of the ultrastrong coupling regime, our experimental data unambiguously reveal the contributions to the polaritonic dynamics coming from the antiresonant terms in the interaction energy and from the dipolar self-energy of the molecular vibrations themselves. In particular, we measure the opening of a genuine vibrational polaritonic band gap of ca. 60 meV. We also demonstrate that the multimode splitting effect defines a whole vibrational ladder of heavy polaritonic states perfectly resolved. These findings reveal the broad possibilities in the vibrational ultrastrong coupling regime which impact both the optical and the molecular properties of such coupled systems, in particular, in the context of mode-selective chemistry.
authors: ISIS and icFRC, Université de Strasbourg and CNRS, 67000 Strasbourg, France.
authors: Jino
authors: J
authors: George
authors: ISIS and icFRC, Université de Strasbourg and CNRS, 67000 Strasbourg, France.
authors: Thibault
authors: T
authors: Chervy
authors: ISIS and icFRC, Université de Strasbourg and CNRS, 67000 Strasbourg, France.|Braude College, Snunit Street 51, Karmiel 2161002, Israel.
authors: Atef
authors: A
authors: Shalabney
authors: ISIS and icFRC, Université de Strasbourg and CNRS, 67000 Strasbourg, France.
authors: Eloïse
authors: E
authors: Devaux
authors: IoT Device Research Laboratories, NEC Corporation, 34 Miyukigaoka, Tsukuba 305-8501, Japan.
authors: Hidefumi
authors: H
authors: Hiura
authors: ISIS and icFRC, Université de Strasbourg and CNRS, 67000 Strasbourg, France.
authors: Cyriaque
authors: C
authors: Genet
authors: ISIS and icFRC, Université de Strasbourg and CNRS, 67000 Strasbourg, France.
authors: Thomas W
authors: TW
authors: Ebbesen