WI. Mini-symposium: Spectroscopy in Traps
Wednesday, 2016-06-22, 01:30 PM
Chemical and Life Sciences B102
SESSION CHAIR: Jos Oomens (Radboud University, Nijmegen, The Netherlands)
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WI01 |
Invited Mini-Symposium Talk |
30 min |
01:30 PM - 02:00 PM |
P2118: ISOLATING SITE-SPECIFIC SPECTRAL SIGNATURES OF INDIVIDUAL WATER MOLECULES IN H-BONDED NETWORKS WITH ISOTOPOMER-SELECTIVE, IR-IR DOUBLE RESONANCE VIBRATIONAL PREDISSOCIATION SPECTROSCOPY |
CONRAD T. WOLKE, MARK JOHNSON, Department of Chemistry, Yale University, New Haven, CT, USA; |
IDEALS Archive (Abstract PDF / Presentation File) |
DOI: https://dx.doi.org/10.15278/isms.2016.WI01 |
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We will discuss an experimental method that directly yields the embedded correlations between the two OH stretches and the intramolecular bending modes associated with a single H2O water molecule embedded in an otherwise all-D isotopologue. This is accomplished using isotopomer-selective IR-IR hole-burning on the Cs+(D2O)5(H2O) clusters formed by gas-phase exchange of a single, intact H2O molecule for D2O in the Cs+(D2O)6 ion. The OH stretching pattern of the Cs+(H2O)6 isotopologue is accurately recovered by superposition of the isotopomer spectra, thus establishing that the H2O incorporation is random and that the OH stretching manifold is largely due to contributions from decoupled water molecules. This behavior enables a powerful new way to extract structural information from vibrational spectra of size-selected clusters by explicitly identifying the local environments responsible for specific infrared features. Extension of this method to address the degree to which OH stretches are decoupled in the protonated water clusters will also be discussed.
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WI02 |
Contributed Talk |
15 min |
02:05 PM - 02:20 PM |
P1685: IR-UV DOUBLE RESONANCE SPECTROSCOPY OF A COLD PROTONATED FIBRIL-FORMING PEPTIDE: NNQQNY·H+ |
ANDREW F DeBLASE, CHRISTOPHER P HARRILAL, PATRICK S. WALSH, SCOTT A McLUCKEY, TIMOTHY S. ZWIER, Department of Chemistry, Purdue University, West Lafayette, IN, USA; |
IDEALS Archive (Abstract PDF / Presentation File) |
DOI: https://dx.doi.org/10.15278/isms.2016.WI02 |
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Protein aggregation to form amyloid-like fibrils is a purported molecular manifestation that leads to Alzheimer’s, Huntington’s, and other neurodegenerative diseases. The propensity for a protein to aggregate is often driven by the presence of glutamine (Q) and asparagine (N) rich tracts within the primary sequence. For example, Eisenberg and coworkers [Nature 2006, 435, 773] have shown by X-ray crystallography that the peptides NNQQNY and GNNQQNY aggregate into a parallel β-sheet configuration with side chains that intercalate into a “steric zipper”. These sequences are commonly found at the N-terminus of the prion-determining domain in the yeast protein Sup35, a typical fibril-forming protein. Herein, we invoke recent advances in cold ion spectroscopy to explore the nascent conformational preferences of the protonated peptides that are generated by electrospray ionization. Towards this aim, we have used UV and IR spectroscopy to record conformation-specific photofragment action spectra of the NNQQNY monomer cryogenically cooled in an octopole ion trap. This short peptide contains 20 hydride stretch oscillators, leading to a rich infrared spectrum with at least 18 resolved transitions in the 2800-3800 cm−1 region. The infrared spectrum suggests the presence of both a free acid OH moiety and an H-bonded tyrosine OH group. We compare our results with resonant ion dip infrared spectra (RIDIRS) of the acyl/NH-benzyl capped neutral glutamine amino acid and its corresponding dipeptide: Ac-Q-NHBn and Ac-QQ-NHBn, respectively. These comparisons bring empirical insight to the NH stretching region of the spectrum, which contains contributions from free and singly H-bonded NH2 side-chain groups, and from peptide backbone amide NH groups. We further compare our spectrum to harmonic calculations at the M05-2X/6-31+G* level of theory, which were performed on low energy structures obtained from Monte Carlo conformational searches using the Amber* and OPLS force fields to assess the presence of sidechain-sidechain and sidechain-backbone interactions.
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WI03 |
Contributed Talk |
15 min |
02:22 PM - 02:37 PM |
P1598: VIBRATIONAL AND ROTATIONAL SPECTROSCOPY
OF CD2H+ |
OSKAR ASVANY, PAVOL JUSKO, SANDRA BRÜNKEN, STEPHAN SCHLEMMER, I. Physikalisches Institut, Universität zu Köln, Köln, Germany; |
IDEALS Archive (Abstract PDF / Presentation File) |
DOI: https://dx.doi.org/10.15278/isms.2016.WI03 |
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The lowest rotational levels (J=0-5) of the CD 2H +
ground state have been probed by high-resolution
rovibrational and pure rotational spectroscopy
in a cryogenic 22-pole ion trap.
For this, the ν 1 rovibrational band has been
revisited M.-F. Jagod et al, J. Molec. Spectrosc. 153, 666, 1992
detecting 107 transitions, among which 35 are new. The use of a frequency comb system allowed to measure
the rovibrational transitions with high precision and accuracy, typically better than 1 MHz.
The high precision has been confirmed by comparing
combination differences in the ground and vibrationally excited state.
For the ground state, this allowed for equally precise
predictions of pure rotational transitions, 24 of which have
been measured directly by a novel IR - mm-wave
double resonance
method S. Gärtner et al, J. Phys. Chem. A 117, 9975, 2013
Footnotes:
M.-F. Jagod et al, J. Molec. Spectrosc. 153, 666, 1992,
S. Gärtner et al, J. Phys. Chem. A 117, 9975, 2013.
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WI04 |
Contributed Talk |
15 min |
02:39 PM - 02:54 PM |
P1604: INFRARED PREDISSOCIATION SPECTROSCOPY OF THE HYDROCARBON CATIONS C3H+, C2H+, and C3H2+ |
SANDRA BRÜNKEN, I. Physikalisches Institut, Universität zu Köln, Köln, Germany; FILIPPO LIPPARINI, JÜRGEN GAUSS, Institut für Physikalische Chemie, Universität Mainz, Mainz, Germany; ALEXANDER STOFFELS, BRITTA REDLICH, LEX VAN DER MEER, GIEL BERDEN, JOS OOMENS, Institute for Molecules and Materials (IMM), Radboud University Nijmegen, Nijmegen, Netherlands; STEPHAN SCHLEMMER, I. Physikalisches Institut, Universität zu Köln, Köln, Germany; |
IDEALS Archive (Abstract PDF / Presentation File) |
DOI: https://dx.doi.org/10.15278/isms.2016.WI04 |
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Reactive hydrocarbon cations play an important role in the astrochemistry of the interstellar medium, but spectroscopic data, needed for their identification in astronomical observations, is sparse. Here we report the first gas-phase vibrational spectra of the linear C3H+ (1 Σ), the radical cation C2H+ (3 Π), and the linear-/cyclic-C3H2+ (2 Π /2A1, resp.). Broadband spectra were recorded by Ne- and He-messenger infrared-predissociation (IR-PD) action spectroscopy in a cryogenic (4−11 K) ion trap instrument (FELion) in the 250−3500 cm−1 range using a free electron laser and a MIR-OPO at the FELIX (Free-Electron Laser for Infrared eXperiments) laboratory. The band positions (determined with a precision of 1−2 cm−1) covering the C-H and C-C stretching as well as several bending modes are compared to high-level (CCSD(T) with large basis sets) quantum-chemical calculations with an emphasis on anharmonic effects and on the influence of the rare-gas messenger atom. The experimental and theoretical data provide a solid basis for subsequent IR high-resolution studies, with the ultimate goal to predict and measure accurate rotational spectra for a radio-astronomical search of these molecular ions in space.
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WI05 |
Contributed Talk |
15 min |
02:56 PM - 03:11 PM |
P1609: FREQUENCY COMB ASSISTED IR MEASUREMENTS OF H3+, H2D+ AND D2H+ TRANSITIONS |
PAVOL JUSKO, OSKAR ASVANY, STEPHAN SCHLEMMER, I. Physikalisches Institut, Universität zu Köln, Köln, Germany; |
IDEALS Archive (Abstract PDF / Presentation File) |
DOI: https://dx.doi.org/10.15278/isms.2016.WI05 |
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We present recent measurements of the fundamental transitions of H 3+, H 2D + and D 2H +
P. Jusko, C. Konietzko, S. Schlemmer, O. Asvany, J. Mol. Spec. 319 (2016) 55n a 4 K 22-pole trap
O. Asvany, S. Brünken, L. Kluge, S. Schlemmer, Appl. Phys. B 114 (2014) 203y action spectroscopic techniques. Either Laser Induced Inhibition of Cluster Growth (He attachment at T ≈ 4 K), endothermic reaction of H 3+ with O 2, or deuterium exchange has been used as measurement scheme.
We used a 3 μm optical parametric oscillator coupled to a frequency comb
O. Asvany, J. Krieg, S. Schlemmer, Rev. Sci. Instr. 83 (2012) 093110n order to achieve accuracy generally below 1 MHz.
Five transitions of H 3+, eleven of H 2D + and ten of D 2H + were recorder in our spectral range.
We compare our H 3+ results with two previous frequency comb assisted works
J.N. Hodges, A.J. Perry, P.A. Jenkins, B.M. Siller, B.J. McCall, J. Chem. Phys. 139 (2013) 164201
H.-C. Chen, C.-Y. Hsiao, J.-L. Peng, T. Amano, J.-T. Shy, Phys. Rev. Lett. 109 (2012) 263002.
Moreover, accurate determination of the frequency allows us to predict pure rotational transitions for H 2D + and D 2H + in the THz range.
Footnotes:
P. Jusko, C. Konietzko, S. Schlemmer, O. Asvany, J. Mol. Spec. 319 (2016) 55i
O. Asvany, S. Brünken, L. Kluge, S. Schlemmer, Appl. Phys. B 114 (2014) 203b
O. Asvany, J. Krieg, S. Schlemmer, Rev. Sci. Instr. 83 (2012) 093110i
J.N. Hodges, A.J. Perry, P.A. Jenkins, B.M. Siller, B.J. McCall, J. Chem. Phys. 139 (2013) 164201
Footnotes:
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03:13 PM |
INTERMISSION |
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WI06 |
Contributed Talk |
15 min |
03:30 PM - 03:45 PM |
P1810: INFRARED SPECTROSCOPY OF IONS IN SELECTED ROTATIONAL AND SPIN-ORBIT STATES |
UGO JACOVELLA, JOSEF A. AGNER, HANSJÜRG SCHMUTZ, FREDERIC MERKT, Laboratorium für Physikalische Chemie, ETH Zurich, Zurich, Switzerland; |
IDEALS Archive (Abstract PDF / Presentation File) |
DOI: https://dx.doi.org/10.15278/isms.2016.WI06 |
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r0pt
Figure
First results are presented obtained using an experimental setup developed to record IR spectra of rotationally state-selected ions. The method we use is a state-selective version of a method developed by Schlemmer et al. Schlemmer et al., J. Chem. Phys. 117, 2068 (2002)o record IR spectra of ions.
Ions are produced in specific rotational levels using mass-analysed threshold ionisation (MATI) spectroscopy combined with single-photon excitation of neutral molecules in supersonic expansions with a vacuum-ultraviolet laser. The ions generated by pulsed-field ionisation of Rydberg states of high principal quantum number ( n ≈ 200) are extracted toward an octupole ion guide containing a neutral target gas. Prior to entering the octupole the ions are excited by an IR laser. The target gas is chosen so that only excited ions react to form product ions. These product ions are detected mass selectively as function of the IR laser wavenumber.
To illustrate this method, we present IR spectra of C 2H 2+ in selected rotational levels of the 2Π 3/2 and 2Π 1/2 spin-orbit components of the electronic ground state.
Footnotes:
Schlemmer et al., J. Chem. Phys. 117, 2068 (2002)t
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WI07 |
Contributed Talk |
15 min |
03:47 PM - 04:02 PM |
P2035: PRECISION SPECTROSCOPY ON SINGLE COLD TRAPPED MOLECULAR NITROGEN IONS |
GREGOR HEGI, KAVEH NAJAFIAN, MATTHIAS GERMANN, ILIA SERGACHEV, STEFAN WILLITSCH, Department of Chemistry, University of Basel, Basel, Switzerland; |
IDEALS Archive (Abstract PDF / Presentation File) |
DOI: https://dx.doi.org/10.15278/isms.2016.WI07 |
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The ability to precisely control and manipulate single cold trapped particles has enabled spectroscopic studies on narrow transitions of ions at unprecedented levels of precision P. O. Schmidt et. al., Science 309 (2005), 749. This has opened up a wide range of applications, from tests of fundamental physical concepts, e.g., possible time-variations of fundamental constants, to new and improved frequency standards.
So far most of these experiments have concentrated on atomic ions. Recently, however, attention has also been focused on molecular species, and molecular nitrogen ions have been identified as promising candidates for testing a possible time-variation of the proton/electron mass ratio M. Kajita et. al., Phys. Rev. A 89 (2014), 032509. Here, we report progress towards precision-spectroscopic studies on dipole-forbidden vibrational transitions in single trapped N 2+ ions M. Germann , X. Tong, S. Willitsch, Nature Physics 10 (2014), 820. Our approach relies on the state-selective generation of single N 2+ ions X. Tong, A. Winney, S. Willitsch, Phys. Rev. Lett. 105 (2010), 143001. subsequent infrared excitation using high intensity, narrow-band quantum-cascade lasers and a quantum-logic scheme for non-destructive state readout. We also characterize processes limiting the state lifetimes in our experiment, which impair the measurement fidelity.
Footnotes:
P. O. Schmidt et. al., Science 309 (2005), 749..
M. Kajita et. al., Phys. Rev. A 89 (2014), 032509..
M. Germann , X. Tong, S. Willitsch, Nature Physics 10 (2014), 820..
X. Tong, A. Winney, S. Willitsch, Phys. Rev. Lett. 105 (2010), 143001.,
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WI08 |
Contributed Talk |
15 min |
04:04 PM - 04:19 PM |
P1887: UV PHOTODISSOCIATION SPECTROSCOPY OF TEMPERATURE CONTROLLED HYDRATED PHENOL CLUSTER CATION |
ITARU KURUSU, REONA YAGI, YASUTOSHI KASAHARA, HARUKI ISHIKAWA, Department of Chemistry, School of Science, Kitasato University, Sagamihara, Japan; |
IDEALS Archive (Abstract PDF / Presentation File) |
DOI: https://dx.doi.org/10.15278/isms.2016.WI08 |
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Owing to various developments of spectroscopic techniques, microscopic hydration structures of various clusters in the gas phase have been determined so far. The next step for further understanding of the microscopic hydration is to reveal the temperature effect, such as a fluctuation of the hydration structure. Thus, we have been carrying out photodissociation spectroscopy on the hydrated phenol cation clusters, [PhOH(H 2O) n] +, trapped in our temperature-variable ion trap H. Ishikawa, T. Nakano, T. Eguchi, T. Shibukawa, K. Fuke, Chem. Phys. Lett. 514, 234 (2011).
After the last symposium R. Yagi, Y. Kasahara, H. Ishikawa, WH12, the 70th International Symposium on Molecular Spectroscopy (2015) we succeeded in improving our experimental condition and recorded the UV photodissociation spectra of [PhOH(H 2O) 5] + at the trap temperatures of 20, 50, and 100 K. We identified three groups of bands by their temperature dependence in the spectra. Based on the results of the DFT calculations, we estimated the temperature dependence of the relative populations among the isomers. As a results, the isomers were grouped into three groups having different motifs of the hydrogen-bond structures. Comparing the experimental with the theoretical results, we assigned the relation between the band carriers and the hydrogen-bond structure motifs. Details of the discussion will be presented in the paper.
Footnotes:
H. Ishikawa, T. Nakano, T. Eguchi, T. Shibukawa, K. Fuke, Chem. Phys. Lett. 514, 234 (2011)..
R. Yagi, Y. Kasahara, H. Ishikawa, WH12, the 70th International Symposium on Molecular Spectroscopy (2015),
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WI09 |
Contributed Talk |
15 min |
04:21 PM - 04:36 PM |
P1923: STRUCTURAL INFORMATION INFERENCE FROM LANTHANOID COMPLEXING SYSTEMS: PHOTOLUMINESCENCE STUDIES ON ISOLATED IONS |
JEAN FRANCOIS GREISCH, MICHAEL E. HARDING, Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe, Germany; JIRI CHMELA, WILLEM M. KLOPPER, Institute of Physical Chemistry, Karlsruhe Institute of Technology, Karlsruhe, Germany; DETLEF SCHOOSS, Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe, Germany; MANFRED M KAPPES, Institute of Physical Chemistry, Karlsruhe Institute of Technology, Karlsruhe, Germany; |
IDEALS Archive (Abstract PDF / Presentation File) |
DOI: https://dx.doi.org/10.15278/isms.2016.WI09 |
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The application of lanthanoid complexes ranges from photovoltaics and light-emitting diodes to quantum memories and biological assays. Rationalization of their design requires a thorough understanding of intramolecular processes such as energy transfer, charge transfer, and non-radiative decay involving their subunits. Characterization of the excited states of such complexes considerably benefits from mass spectrometric methods since the associated optical transitions and processes are strongly affected by stoichiometry, symmetry, and overall charge state. We report herein spectroscopic measurements on ensembles of ions trapped in the gas phase and soft-landed in neon matrices. Their interpretation is considerably facilitated by direct comparison with computations.
The combination of energy- and time-resolved measurements on isolated species with density functional as well as ligand-field and Franck-Condon computations enables us to infer structural as well as dynamical information about the species studied. The approach is first illustrated for sets of model lanthanoid complexes whose structure and electronic properties are systematically varied via the substitution of one component (lanthanoid or alkali,alkali-earth ion): (i) systematic dependence of ligand-centered phosphorescence on the lanthanoid(III) promotion energy and its impact on sensitization, and (ii) structural changes induced by the substitution of alkali or alkali-earth ions in relation with structures inferred using ion mobility spectroscopy. The temperature dependence of sensitization is briefly discussed. The focus is then shifted to measurements involving europium complexes with doxycycline an antibiotic of the tetracycline family. Besides discussing the complexes’ structural and electronic features, we report on their use to monitor enzymatic processes involving hydrogen peroxide or biologically relevant molecules such as adenosine triphosphate (ATP).
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WI10 |
Contributed Talk |
15 min |
04:38 PM - 04:53 PM |
P1989: PHOTO-IONIZATION AND PHOTO-DISSOCIATION OF TRAPPED PAH CATIONS |
CHRISTINE JOBLIN, JUNFENG ZHEN, SARAH RODRIGUEZ CASTILLO, GIACOMO MULAS, HASSAN SABBAH, IRAP, Université de Toulouse 3 - CNRS, Toulouse, France; AUDE SIMON, LCPQ, Université de Toulouse 3 - CNRS, Toulouse, France; ALEXANDRE GIULIANI, LAURENT NAHON, DESIRS beamline, Synchrotron SOLEIL, Gif-sur-Yvette, France; SERGE MARTIN, UMR 5306, ILM University Lyon 1 and CNRS, Villeurbanne, France; JEAN-PHILIPPE CHAMPEAUX, LCAR, Université de Toulouse 3 - CNRS, Toulouse, France; PAUL M. MAYER, Department of Chemistry and Biomolecular Sciences,, University of Ottawa, Ottawa, Canada; |
IDEALS Archive (Abstract PDF / Presentation File) |
DOI: https://dx.doi.org/10.15278/isms.2016.WI10 |
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In astrophysical environments, polycyclic aromatic hydrocarbons (PAHs) are submitted to VUV photons of energy up to ∼ 20 eV. In the laboratory, photoelectron-photoion spectroscopy is usually performed using VUV synchrotron radiation, in which the same photon (15-25 eV), is used to ionize and dissociate PAHs H.W. Jochims et al., Astron. & Astrophys. 420 (1994), 307-317; P. M. Mayer et al., J. Chem. Phys. 134 (2011), 244312-244312-8
These experiments explore specific conditions and complementary studies in ion traps are required for a wider investigation of interstellar conditions.
We have used the LTQ linear ion trap available on the DESIRS VUV beamline at SOLEIL to study the interaction of PAH cations with photons in the 7-20 eV range. We recorded by action spectroscopy the relative intensities of photo-fragmentation and photo-ionization of eight PAH cations ranging in size from 14 to 24 carbon atoms and with different structures. We found that, at photon energies below ∼ 13.6 eV, fragmentation dominates for the smaller species, while for larger species ionization is competitive immediately above the second ionization
potential. At higher photon energies, all species behave similarly, the ionization yield gradually increases, levelling off between 0.8 and 0.9 at ∼ 18 eV J. Zhen et al., Astron. & Astrophys. (2016), in press
We have also recorded the competition between the different dissociation channels as a function of the VUV photon energy, such as the C 2H 2 versus H/H 2 loss. We will discuss how these data can be compared to results of photoelectron spectroscopy performed on neutral PAHs at the VUV beamline at the Swiss Light Source. B. West et al., J. Phys. Chem. A 118 (2014), 7824-7831; B. West et al., J. Phys. Chem. A 118 (2014), 9870-9878 Acknowledgments European Research Council grant ERC-2013-SyG, Grant Agreement n. 610256 NANOCOSMOS.html:<hr /><h3>Footnotes:
H.W. Jochims et al., Astron. & Astrophys. 420 (1994), 307-317; P. M. Mayer et al., J. Chem. Phys. 134 (2011), 244312-244312-8.
J. Zhen et al., Astron. & Astrophys. (2016), in press.
B. West et al., J. Phys. Chem. A 118 (2014), 7824-7831; B. West et al., J. Phys. Chem. A 118 (2014), 9870-9878.
European Research Council grant ERC-2013-SyG, Grant Agreement n. 610256 NANOCOSMOS.
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WI11 |
Contributed Talk |
15 min |
04:55 PM - 05:10 PM |
P2094: PROGRESS OF THE JILA ELECTRON EDM EXPERIMENT |
YAN ZHOU, WILLIAM CAIRNCROSS, MATT GRAU, DAN GRESH, KIA BOON NG, YIQI NI, JUN YE, ERIC CORNELL, JILA, NIST, and Department of Physics, University of Colorado Boulder, Boulder, CO, USA; |
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DOI: https://dx.doi.org/10.15278/isms.2016.WI11 |
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A more accurate value for the permanent electric dipole moment of the electron (eEDM), whether consistent with zero or otherwise, will have important implications for extensions to the Standard Model. The JILA eEDM experiment uses trapped HfF+ ions to attain a large effective electric field and a long measurement coherence time. We prepare HfF+ ions in a low-lying, metastable 3∆1 state and perform Ramsey spectroscopy with free-evolution times of > 500 ms between two Zeeman sub-levels in the presence of rotating bias electric and magnetic fields. In this talk, we present initial results of an eEDM-sensitive 100-hour data run and a thorough investigation of various systematic errors. Several of our leading systematics have been suppressed to the 10−30 e.cm level. In addition, we report two ongoing experiments aimed towards increasing the statistical sensitivity: (1) applying STImulated Raman Adiabatic Passage (STIRAP) for increased coherent population transfer to the eEDM-sensitive 3∆1 state; and (2) implementing a new ion counting detector for increased detection efficiency and for suppressing shot-to-shot noise.
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