Anharmonic vibrational polaritons in the ultrastrong coupling regime: Nonlinear spectroscopy and chemical reactivity

Light-matter interaction of molecular vibrations with confined infrared fields is a powerful resource for controlling the spectroscopy and chemical reactivity of molecular materials [1]. Experiments show that the properties of vibrational polariton states can strongly depend on the detailed internal structure of the coupled molecules [2]. We introduce fully-quantum theory for the coupling of a Morse oscillator with an infrared cavity, taking into account both transition and permanent molecular dipole moments [3], and show that at the onset of ultrastrong coupling, polar molecular modes can spontaneously dissociate when placed inside a cavity [4]. The same theory has been successfully used to describe ultrafast polariton-to-polariton transitions in two-dimensional infrared cavity spectroscopy [5]. Our work thus offers mechanistic insights on the spectroscopy and chemistry hybrid vibration-cavity states.

[1] F. Herrera and J. Owrutsky. J. Chem. Phys. 152, 100902, 2020.
[2] Y. Pang et al, Angew. Chem. Int. Ed. 59, 10436, 2020.
[3] J. F. Triana et al, J. Chem. Phys. 152, 234111, 2020; F. Hernández and F. Herrera, J. Chem. Phys. 151, 144116, 2019.
[4] J. F. Triana, F. Herrera. DOI:10.26434/chemrxiv.12702419.v1, 2020.
[5] A.B. Grafton et al. DOI: 10.26434/chemrxiv.12518555.v1, 2020.