Excited rotational states of molecules in a superfluid

Cherepanov, Igor N.; Bighin, Giacomo; Schouder, Constant A.; Chatterley, Adam S.; Albrechtsen, Simon H.; Muñoz, Alberto Viñas; Christiansen, Lars; Stapelfeldt, Henrik; Lemeshko, Mikhail

doi:10.1103/physreva.104.l061303

Cited by 7 publications

(12 citation statements)

References 29 publications

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“…The present study builds upon our recent experimental and theoretical work [10], where we briefly sketched the model and showed that it provides a good agreement with experimental data for CS 2 and I 2 molecules up to J ∼ 16. Here, apart from describing the theoretical machinery of our model in more detail, we gain several novel insights into the highly excited states and connect their behavior to the large amount of experimental data available for the states with low angular momentum.…”

Section: Introductionmentioning

confidence: 57%

“…Thus we presented a simple quantum mechanical model describing the rotational level structure of molecules in superfluid helium nanodroplets and, in particular, capturing highly excited states (recent work [10] compared the model calculations with experiment up to J 16 for I 2 and CS 2 molecules). Here we provided details on the theoretical machinery of the model, benchmarked its results against the data on the effective spectroscopic constants B * and D * for a broad range of molecules.…”

Section: Discussionmentioning

confidence: 99%

“…The classification of different L-Λ coupling schemes in terms of Hund's cases (in analogy with gas-phase species) is another interesting problem that is not going to be discussed here. Furthermore, we omit the detailed discussion of molecule-bath angular momentum transfer, that has already been presented elsewhere [10].…”

Section: The Angulon Hamiltonianmentioning

confidence: 99%

“…The model described in section 2 has already been successfully used to describe experimental data on rotational states of CS 2 and I 2 molecules up to J ∼ 16 [10]. The experimental data available on highly excited rotational states is, however, still quite limited and it is important to place the model in the context of the large amount of measurements for the low-J excitations.…”

Section: Scaling Of Spectroscopic Constantsmentioning

confidence: 99%

“…Recently it became possible to experimentally probe highly excited rotational states of molecules in helium nanodroplets using non-adiabatic alignment protocols [7][8][9][10]. Namely, analysing the Fourier transforms of alignment traces allowed to reveal the energies and lifetimes of rotational levels in superfluid 4 He, up to J ∼ 16.…”

Section: Introductionmentioning

confidence: 99%

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A simple model for high rotational excitations of molecules in a superfluid

et al. 2022

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Recently it became possible to study highly excited rotational states of molecules in superfluid helium through nonadiabatic alignment experiments [Cherepanov \et al., Phys. Rev. A 104, L061303 (2021)]. This calls for theoretical approaches that go beyond explaining renormalized values of molecular spectroscopic constants, which suffices when only the lowest few rotational states are involved. As the first step in this direction, here we present a basic quantum mechanical model describing highly excited rotational states of molecules in superfluid helium nanodroplets. We show that a linear molecule immersed in a superfluid can be seen as an effective symmetric top, similar to the rotational structure of radicals, such as OH or NO, but with the angular momentum of the superfluid playing the role of the electronic angular momentum in free molecules. The simple theory sheds light onto what happens when the rotational angular momentum of the molecule increases beyond the lowest excited states accessible by infrared spectroscopy. In addition, the model allows to estimate the effective rotational and centrifugal distortion constants for a broad range of species and to explain the crossover between light and heavy molecules in superfluid $^4$He in terms of the many-body wavefunction structure. Some of the above mentioned insights can be acquired by analyzing a simple 2x2 matrix.

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Section: Introductionmentioning

confidence: 57%

Section: Discussionmentioning

confidence: 99%

Section: The Angulon Hamiltonianmentioning

confidence: 99%

Section: Scaling Of Spectroscopic Constantsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A simple model for high rotational excitations of molecules in a superfluid

et al. 2022

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Optical absorption of angulon in metal halide perovskites

Wu,

Cui,

et al. 2023

Physica B: Condensed Matter

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Variational theory of angulons and their rotational spectroscopy

Zeng

Yakaboylu

Lemeshko

et al. 2023

The Journal of Chemical Physics

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The angulon, a quasiparticle formed by a quantum rotor dressed by the excitations of a many-body bath, can be used to describe an impurity rotating in a fluid or solid environment. Here we propose a coherent state ansatz in the co-rotating frame which provides a comprehensive theoretical description of angulons. We reveal the quasiparticle properties, such as energies, quasiparticle weights and spectral functions, and show that our ansatz yields a persistent decrease in the impurity's rotational constant due to many-body dressing, consistent with experimental observations. From our study, a picture of the angulon emerges as an effective spin interacting with a magnetic field that is self-consistently generated by the molecule's rotation. Moreover, we discuss rotational spectroscopy, which focuses on the response of rotating molecules to a laser perturbation in the linear response regime. Importantly, we take into account initial-state interactions that have been neglected in prior studies and reveal their impact on the excitation spectrum. To examine the angulon instability regime, we use a single-excitation ansatz and obtain results consistent with experiments, in which a broadening of spectral lines is observed while phonon wings remain highly suppressed due to initial-state interactions.

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Excited rotational states of molecules in a superfluid

Cited by 7 publications

References 29 publications

A simple model for high rotational excitations of molecules in a superfluid

A simple model for high rotational excitations of molecules in a superfluid

Optical absorption of angulon in metal halide perovskites

Variational theory of angulons and their rotational spectroscopy

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