Strongly aligned molecules inside helium droplets in the near-adiabatic regime

B. Shepperson, A. Chatterley, A. Søndergaard, L. Christiansen, M. Lemeshko, H. Stapelfeldt, The Journal of Chemical Physics 147 (2017).


Journal Article | Published | English
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Abstract
Iodine (I 2 ) molecules embedded in He nanodroplets are aligned by a 160 ps long laser pulse. The highest degree of alignment, occurring at the peak of the pulse and quantified by ⟨cos 2 θ 2D ⟩ , is measured as a function of the laser intensity. The results are well described by ⟨cos 2 θ 2D ⟩ calculated for a gas of isolated molecules each with an effective rotational constant of 0.6 times the gas-phase value, and at a temperature of 0.4 K. Theoretical analysis using the angulon quasiparticle to describe rotating molecules in superfluid helium rationalizes why the alignment mechanism is similar to that of isolated molecules with an effective rotational constant. A major advantage of molecules in He droplets is that their 0.4 K temperature leads to stronger alignment than what can generally be achieved for gas phase molecules -- here demonstrated by a direct comparison of the droplet results to measurements on a ∼ 1 K supersonic beam of isolated molecules. This point is further illustrated for more complex system by measurements on 1,4-diiodobenzene and 1,4-dibromobenzene. For all three molecular species studied the highest values of ⟨cos 2 θ 2D ⟩ achieved in He droplets exceed 0.96.
Publishing Year
Date Published
2017-06-01
Journal Title
The Journal of Chemical Physics
Volume
147
Issue
1
Article Number
013946
ISSN
IST-REx-ID

Cite this

Shepperson B, Chatterley A, Søndergaard A, Christiansen L, Lemeshko M, Stapelfeldt H. Strongly aligned molecules inside helium droplets in the near-adiabatic regime. The Journal of Chemical Physics. 2017;147(1). doi:10.1063/1.4983703
Shepperson, B., Chatterley, A., Søndergaard, A., Christiansen, L., Lemeshko, M., & Stapelfeldt, H. (2017). Strongly aligned molecules inside helium droplets in the near-adiabatic regime. The Journal of Chemical Physics, 147(1). https://doi.org/10.1063/1.4983703
Shepperson, Benjamin, Adam Chatterley, Anders Søndergaard, Lars Christiansen, Mikhail Lemeshko, and Henrik Stapelfeldt. “Strongly Aligned Molecules inside Helium Droplets in the Near-Adiabatic Regime.” The Journal of Chemical Physics 147, no. 1 (2017). https://doi.org/10.1063/1.4983703.
B. Shepperson, A. Chatterley, A. Søndergaard, L. Christiansen, M. Lemeshko, and H. Stapelfeldt, “Strongly aligned molecules inside helium droplets in the near-adiabatic regime,” The Journal of Chemical Physics, vol. 147, no. 1, 2017.
Shepperson B, Chatterley A, Søndergaard A, Christiansen L, Lemeshko M, Stapelfeldt H. 2017. Strongly aligned molecules inside helium droplets in the near-adiabatic regime. The Journal of Chemical Physics. 147(1).
Shepperson, Benjamin, et al. “Strongly Aligned Molecules inside Helium Droplets in the Near-Adiabatic Regime.” The Journal of Chemical Physics, vol. 147, no. 1, 013946, AIP, 2017, doi:10.1063/1.4983703.

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