Nonadiabatic laser-induced alignment dynamics of alkali-metal dimers on the surface of a helium droplet

Henrik H. Kristensen; Lorenz Kranabetter; Areg Ghazaryan; Constant A. Schouder; Emil Hansen; Frank Jensen; Robert E. Zillich; Mikhail Lemeshko; Henrik Stapelfeldt

doi:10.1103/PhysRevA.111.033114

Nonadiabatic laser-induced alignment dynamics of alkali-metal dimers on the surface of a helium droplet

Henrik H. Kristensen, Lorenz Kranabetter, Areg Ghazaryan, Constant A. Schouder, Emil Hansen, Frank Jensen, Robert E. Zillich, Mikhail Lemeshko, Henrik Stapelfeldt^*

^*Corresponding author for this work

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

Abstract

Alkali-metal dimers, Ak2, located on the surface of a helium nanodroplet, are set into rotation through the polarizability interaction with a nonresonant 1-ps-long laser pulse. The time-dependent degree of alignment is recorded using femtosecond-probe-pulse-induced Coulomb explosion into a pair of Ak+ fragment ions. The results, obtained for Na2, K2, and Rb2 in both the ground state 11ςg+ and the lowest-lying triplet state 13ςu+, exhibit distinct, periodic revivals with a gradually decreasing amplitude. The dynamics differ from that expected for dimers had they behaved as free rotors. Numerically, we solve the time-dependent rotational Schrödinger equation, including an effective mean-field potential to describe the interaction between the dimer and the droplet. The experimental and simulated alignment dynamics agree well and their comparison enables us to determine the effective rotational constants of the alkali dimers with the exception of Rb2(13ςu+) that only exhibits a prompt alignment peak but no subsequent revivals. For Na2(13ςu+), K2(11ςg+), K2(13ςu+), and Rb2(11ςg+), the alignment dynamics are well described by a two-dimensional rotor model. We ascribe this to a significant confinement of the internuclear axis of these dimers, induced by the orientation-dependent droplet-dimer interaction, to the tangential plane of their residence point on the droplet.

Original language	English
Article number	033114
Journal	Physical Review A
Volume	111
Issue	3
Number of pages	11
ISSN	2469-9926
DOIs	https://doi.org/10.1103/PhysRevA.111.033114
Publication status	Published - Mar 2025

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title = "Nonadiabatic laser-induced alignment dynamics of alkali-metal dimers on the surface of a helium droplet",

abstract = "Alkali-metal dimers, Ak2, located on the surface of a helium nanodroplet, are set into rotation through the polarizability interaction with a nonresonant 1-ps-long laser pulse. The time-dependent degree of alignment is recorded using femtosecond-probe-pulse-induced Coulomb explosion into a pair of Ak+ fragment ions. The results, obtained for Na2, K2, and Rb2 in both the ground state 11ςg+ and the lowest-lying triplet state 13ςu+, exhibit distinct, periodic revivals with a gradually decreasing amplitude. The dynamics differ from that expected for dimers had they behaved as free rotors. Numerically, we solve the time-dependent rotational Schr{\"o}dinger equation, including an effective mean-field potential to describe the interaction between the dimer and the droplet. The experimental and simulated alignment dynamics agree well and their comparison enables us to determine the effective rotational constants of the alkali dimers with the exception of Rb2(13ςu+) that only exhibits a prompt alignment peak but no subsequent revivals. For Na2(13ςu+), K2(11ςg+), K2(13ςu+), and Rb2(11ςg+), the alignment dynamics are well described by a two-dimensional rotor model. We ascribe this to a significant confinement of the internuclear axis of these dimers, induced by the orientation-dependent droplet-dimer interaction, to the tangential plane of their residence point on the droplet.",

author = "Kristensen, {Henrik H.} and Lorenz Kranabetter and Areg Ghazaryan and Schouder, {Constant A.} and Emil Hansen and Frank Jensen and Zillich, {Robert E.} and Mikhail Lemeshko and Henrik Stapelfeldt",

note = "Publisher Copyright: {\textcopyright} 2025 American Physical Society. ",

year = "2025",

month = mar,

doi = "10.1103/PhysRevA.111.033114",

language = "English",

volume = "111",

journal = "Physical Review A",

issn = "2469-9926",

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number = "3",

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Nonadiabatic laser-induced alignment dynamics of alkali-metal dimers on the surface of a helium droplet. / Kristensen, Henrik H.; Kranabetter, Lorenz; Ghazaryan, Areg et al.
In: Physical Review A, Vol. 111, No. 3, 033114, 03.2025.

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

TY - JOUR

T1 - Nonadiabatic laser-induced alignment dynamics of alkali-metal dimers on the surface of a helium droplet

AU - Kristensen, Henrik H.

AU - Kranabetter, Lorenz

AU - Ghazaryan, Areg

AU - Schouder, Constant A.

AU - Hansen, Emil

AU - Jensen, Frank

AU - Zillich, Robert E.

AU - Lemeshko, Mikhail

AU - Stapelfeldt, Henrik

PY - 2025/3

Y1 - 2025/3

N2 - Alkali-metal dimers, Ak2, located on the surface of a helium nanodroplet, are set into rotation through the polarizability interaction with a nonresonant 1-ps-long laser pulse. The time-dependent degree of alignment is recorded using femtosecond-probe-pulse-induced Coulomb explosion into a pair of Ak+ fragment ions. The results, obtained for Na2, K2, and Rb2 in both the ground state 11ςg+ and the lowest-lying triplet state 13ςu+, exhibit distinct, periodic revivals with a gradually decreasing amplitude. The dynamics differ from that expected for dimers had they behaved as free rotors. Numerically, we solve the time-dependent rotational Schrödinger equation, including an effective mean-field potential to describe the interaction between the dimer and the droplet. The experimental and simulated alignment dynamics agree well and their comparison enables us to determine the effective rotational constants of the alkali dimers with the exception of Rb2(13ςu+) that only exhibits a prompt alignment peak but no subsequent revivals. For Na2(13ςu+), K2(11ςg+), K2(13ςu+), and Rb2(11ςg+), the alignment dynamics are well described by a two-dimensional rotor model. We ascribe this to a significant confinement of the internuclear axis of these dimers, induced by the orientation-dependent droplet-dimer interaction, to the tangential plane of their residence point on the droplet.

AB - Alkali-metal dimers, Ak2, located on the surface of a helium nanodroplet, are set into rotation through the polarizability interaction with a nonresonant 1-ps-long laser pulse. The time-dependent degree of alignment is recorded using femtosecond-probe-pulse-induced Coulomb explosion into a pair of Ak+ fragment ions. The results, obtained for Na2, K2, and Rb2 in both the ground state 11ςg+ and the lowest-lying triplet state 13ςu+, exhibit distinct, periodic revivals with a gradually decreasing amplitude. The dynamics differ from that expected for dimers had they behaved as free rotors. Numerically, we solve the time-dependent rotational Schrödinger equation, including an effective mean-field potential to describe the interaction between the dimer and the droplet. The experimental and simulated alignment dynamics agree well and their comparison enables us to determine the effective rotational constants of the alkali dimers with the exception of Rb2(13ςu+) that only exhibits a prompt alignment peak but no subsequent revivals. For Na2(13ςu+), K2(11ςg+), K2(13ςu+), and Rb2(11ςg+), the alignment dynamics are well described by a two-dimensional rotor model. We ascribe this to a significant confinement of the internuclear axis of these dimers, induced by the orientation-dependent droplet-dimer interaction, to the tangential plane of their residence point on the droplet.

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U2 - 10.1103/PhysRevA.111.033114

DO - 10.1103/PhysRevA.111.033114

M3 - Journal article

AN - SCOPUS:105001046106

SN - 2469-9926

VL - 111

JO - Physical Review A

JF - Physical Review A

IS - 3

M1 - 033114

ER -

Nonadiabatic laser-induced alignment dynamics of alkali-metal dimers on the surface of a helium droplet

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