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Title: Sympathetic Cooling of Complex Molecular Ions to Millikelvin Temperatures

Abstract

Gas-phase singly protonated organic molecules of mass 410 Da (Alexa Fluor 350) have been cooled from ambient temperature to the hundred millikelvin range by Coulomb interaction with laser-cooled barium ions. The molecules were generated by an electrospray ionization source, transferred to and stored in a radio-frequency trap together with the atomic ions. Observations are well described by molecular dynamics simulations, which are used to determine the spatial distribution and thermal energy of the molecules. In one example, an ensemble of 830 laser-cooled {sup 138}Ba{sup +} ions cooled 200 molecular ions to less than 115 mK. The demonstrated technique should allow a large variety of protonated molecules to be sympathetically cooled, including molecules of much higher mass, such as proteins.

Authors:
; ; ; ; ;  [1]
  1. Institut fuer Experimentalphysik, Heinrich-Heine-Universitaet Duesseldorf, 40225 Duesseldorf (Germany)
Publication Date:
OSTI Identifier:
20861480
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 97; Journal Issue: 24; Other Information: DOI: 10.1103/PhysRevLett.97.243005; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; AMBIENT TEMPERATURE; ATOMIC IONS; BARIUM 138; BARIUM IONS; COOLING; IONIZATION; LASERS; MASS; MOLECULAR DYNAMICS METHOD; MOLECULAR IONS; MOLECULES; RADIOWAVE RADIATION; SIMULATION; SPATIAL DISTRIBUTION; TRAPS

Citation Formats

Ostendorf, A., Zhang, C. B., Wilson, M. A., Offenberg, D., Roth, B., and Schiller, S. Sympathetic Cooling of Complex Molecular Ions to Millikelvin Temperatures. United States: N. p., 2006. Web. doi:10.1103/PHYSREVLETT.97.243005.
Ostendorf, A., Zhang, C. B., Wilson, M. A., Offenberg, D., Roth, B., & Schiller, S. Sympathetic Cooling of Complex Molecular Ions to Millikelvin Temperatures. United States. doi:10.1103/PHYSREVLETT.97.243005.
Ostendorf, A., Zhang, C. B., Wilson, M. A., Offenberg, D., Roth, B., and Schiller, S. Fri . "Sympathetic Cooling of Complex Molecular Ions to Millikelvin Temperatures". United States. doi:10.1103/PHYSREVLETT.97.243005.
@article{osti_20861480,
title = {Sympathetic Cooling of Complex Molecular Ions to Millikelvin Temperatures},
author = {Ostendorf, A. and Zhang, C. B. and Wilson, M. A. and Offenberg, D. and Roth, B. and Schiller, S.},
abstractNote = {Gas-phase singly protonated organic molecules of mass 410 Da (Alexa Fluor 350) have been cooled from ambient temperature to the hundred millikelvin range by Coulomb interaction with laser-cooled barium ions. The molecules were generated by an electrospray ionization source, transferred to and stored in a radio-frequency trap together with the atomic ions. Observations are well described by molecular dynamics simulations, which are used to determine the spatial distribution and thermal energy of the molecules. In one example, an ensemble of 830 laser-cooled {sup 138}Ba{sup +} ions cooled 200 molecular ions to less than 115 mK. The demonstrated technique should allow a large variety of protonated molecules to be sympathetically cooled, including molecules of much higher mass, such as proteins.},
doi = {10.1103/PHYSREVLETT.97.243005},
journal = {Physical Review Letters},
number = 24,
volume = 97,
place = {United States},
year = {Fri Dec 15 00:00:00 EST 2006},
month = {Fri Dec 15 00:00:00 EST 2006}
}
  • We report a high-resolution spectroscopic study of molecular ions at millikelvin temperatures. We measured several rovibrational infrared transitions in HD{sup +} molecular ions, stored in a radio-frequency trap and sympathetically cooled to {approx_equal}20 mK by laser-cooled Be{sup +} ions. We observed hyperfine splitting of the lines, in good agreement with theoretical predictions. The transitions were detected by monitoring the decrease in ion number after selective photodissociation of HD{sup +} ions in the upper vibrational state. The method described here is expected to be generally applicable.
  • We present a new method for the generation of rotationally and vibrationally state-selected, translationally cold molecular ions in ion traps. Our technique is based on the state-selective threshold photoionization of neutral molecules followed by sympathetic cooling of the resulting ions with laser-cooled calcium ions. Using N{sub 2}{sup +} ions as a test system, we achieve >90% selectivity in the preparation of the ground rovibrational level and state lifetimes on the order of 15 minutes limited by collisions with background-gas molecules. The technique can be employed to produce a wide range of apolar and polar molecular ions in the ground andmore » excited rovibrational states. Our approach opens up new perspectives for cold quantum-controlled ion-molecule-collision studies, frequency-metrology experiments with state-selected molecular ions and molecular-ion qubits.« less
  • A large sample (N{approx_equal}10{sup 4}) of fullerene ions (m=720 a.u) is cooled by means of a much smaller number({approx_equal}100) of laser-cooled magnesium ions (m=24 a.u). The results demonstrate that sympathetic cooling of large molecules to low temperatures is feasible. The temperature of the {sup 24}Mg{sup +} ions in the mixed Mg{sup +}-C{sub 60}{sup +} ion cloud stored in an rf trap is found to be T{sub Mg}=5 K from their fluorescence signal. Molecular dynamics simulations are used to obtain the corresponding equilibrium temperature of the fullerene ions, and show that T{sub C{sub 60}}=14 K.
  • Coulomb crystals, containing up to a few hundred ions of which more than 50{percent} were cooled sympathetically by the Coulomb interaction with laser cooled Mg{sup +} ions, have been produced in a linear Paul trap. By controlling the balance of the radiation pressure from the two cooling lasers, the Coulomb crystals could be segregated according to ion species. Previous studies of ion crystals and molecular dynamics simulations suggest that the temperature may be around 10 mK or lower. The obtained results indicate that a wide range of atomic and molecular ions, which due to their internal structures are not amenablemore » to direct laser cooling, can be effectively cooled and localized (crystallized) in linear Paul traps. For high resolution spectroscopy of such ions this may turn out to be very useful. {copyright} {ital 1999 American Institute of Physics.}« less
  • One limit to the fidelity of quantum logic operations on trapped ions arises from heating of the ions' collective modes of motion. Sympathetic cooling of the ions during the logic operations may eliminate this source of errors. We discuss the benefits and drawbacks of this proposal, and describe possible experimental implementations. We also present an overview of trapped-ion dynamics in this scheme. (c) 2000 The American Physical Society.