# Anastasia BorschevskyUniversity of Groningen | RUG · The Van Swinderen Institute for Particle Physics and Gravity

Anastasia Borschevsky

PhD

## About

156

Publications

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Introduction

Additional affiliations

August 2012 - July 2014

November 2009 - July 2012

October 2003 - October 2009

## Publications

Publications (156)

We present the conceptual design of an experiment to measure the electron's electric dipole moment (eEDM) using $^{138}$BaOH molecules in an optical lattice. The BaOH molecule is laser-coolable and highly sensitive to the eEDM, making it an attractive candidate for such a precision measurement, and capturing it in an optical lattice offers potentia...

In this work, the molecular enhancement factors of the $\mathcal{P,T}$-odd interactions involving the electron electric dipole moment ($W_\mathrm{d}$) and the scalar-pseudoscalar nucleon-electron couplings ($W_\mathrm{s}$) are computed for the ground state of the bimetallic molecules YbCu, YbAg and YbAu. These systems offer a promising venue for cr...

The calculations of the first and the second ionization potentials of lawrencium and lutetium and the electron affinity of lawrencium are performed within the relativistic coupled-cluster framework. These results are corrected by including the contributions of extrapolation to the complete basis set limit and higher-order contributions due to relat...

We propose a laser resonance chromatography (LRC) experiment on 229Th3+, with the goal of detecting the ion's electronic ground 5𝑓 2𝐹5/2 state and metastable 7𝑠 2𝑆1/2 state by means of their ion mobilities. To this end, we first model the ion-neutral interaction potentials for the two electronic states with a relativistic Fock space coupled clu...

DOI:https://doi.org/10.1103/PhysRevLett.133.059901

Molecules containing short-lived, radioactive nuclei are uniquely positioned to enable a wide range of scientific discoveries in the areas of fundamental symmetries, astrophysics, nuclear structure, and chemistry. Recent advances in the ability to create, cool, and control complex molecules down to the quantum level, along with recent and upcoming...

We propose a theoretically designed laser resonance chromatography (LRC) experiment on Rf+ (𝑍=104) drifting in He buffer gas. To this end, we first developed a four-level rate equation model that simulates the optical pumping of Rf+ from its ground state, 2𝐷3/2 (7𝑠26𝑑1), to the metastable 4𝐹3/2 (7𝑠16𝑑2) state via laser resonant excitation of...

The calculations for the first and second ionization potentials of lawrencium and lutetium and the electron affinity of lawrencium are performed with Dirac-Coulomb-Breit relativistic coupled cluster method. The contributions of extrapolation of complete basis set limit for uncontracted Dyall basis set and higher order corrections are added to the c...

Recently, we have demonstrated a method to record the longitudinal phase-space distribution of a pulsed cryogenic buffer gas cooled beam of barium fluoride molecules with high resolution. In this paper, we use this method to determine the influence of various source parameters. Besides the expected dependence on temperature and pressure, the forwar...

Closed-shell atoms and molecules such as Hg and TlF provide some of the best low-energy tests of hadronic CP violation beyond the standard model of particle physics, which is considered to be a necessary ingredient to explain the observed excess of matter over antimatter in our universe. CP violation is expected to be strongly enhanced in octupole-...

The nuclear charge radius of Si32 was determined using collinear laser spectroscopy. The experimental result was confronted with ab initio nuclear lattice effective field theory, valence-space in-medium similarity renormalization group, and mean field calculations, highlighting important achievements and challenges of modern many-body methods. The...

We present a comprehensive theoretical study of the ionization potentials of the MF (M=Ca, Sr, and Ba) molecules using the state-of-the-art relativistic coupled-cluster approach with single, double, and perturbative triple excitations [CCSD(T)]. We have further corrected our results for higher-order excitations (up to full triples) and the QED self...

We propose a theoretically designed laser resonance chromatography (LRC) experiment on Rf + (Z = 104) drifting in He buffer gas. To this end, we first developed a four-level rate equation model that simulates the optical pumping of Rf + from its ground state, 2 D 3/2 (7s 2 6d 1), to the metastable 4 F 3/2 (7s 1 6d 2) state via laser resonant excita...

Closed-shell atoms and molecules such as Hg or TlF provide some of the best low-energy tests of hadronic CP-violation which is considered to be a necessary ingredient to explain the observed excess of matter over antimatter in our universe. CP-violation is, however, expected to be strongly enhanced in octupole deformed nuclei such as 225 Ra. Recent...

The isotopically chiral molecular ion CHDBrI ⁺ is identified as an exceptionally promising candidate for the detection of parity violation in vibrational transitions. The largest predicted parity-violating frequency shift reaches 1.8...

Parity non-conservation (PNC) due to the weak interaction is predicted to give rise to enantiomer dependent vibrational constants in chiral molecules, but the phenomenon has so far eluded experimental observation. The enhanced sensitivity of molecules to physics beyond the Standard Model (BSM) has led to substantial advances in molecular precision...

We report measured and calculated values of radiative decay rates and vibrational branching fractions for the A2Π(v=0) state of Mg24F19. The decay rate measurements use time-correlated single-photon counting with roughly 1% total uncertainty. Branching-fraction measurements are performed using two calibrated imaging systems to achieve few percent t...

The nuclear charge radius of $^{32}$Si was determined using collinear laser spectroscopy. The experimental result was confronted with ab initio nuclear lattice effective field theory, valence-space in-medium similarity renormalization group, and mean field calculations, highlighting important achievements and challenges of modern many-body methods....

We present a comprehensive theoretical study of the ionization potentials of the MF (M= Ca, Sr, Ba) molecules using the state-of-the-art relativistic coupled cluster approach with single, double, and perturbative triple excitations (CCSD(T)). We have further corrected our results for the higher order excitations (up to full triples) and the QED sel...

We report the spectroscopy of 11 electronic states in the radioactive molecule radium monofluoride (RaF). The observed excitation energies are compared with state-of-the-art relativistic Fock-space coupled cluster (FS-RCC) calculations, which achieve an agreement of >99.71% (within ~8 meV) for all states. High-order electron correlation and quantum...

Ion mobilities of Lr+ (Z=103) and of its lighter chemical homolog Lu+ (Z=71) in helium were calculated for the ground state S01 and the lowest metastable state D13. To this end we applied the multireference configuration interaction method to calculate the ion-atom interaction potentials in the different states. The Gram-Charlier approach to solvin...

Parity non-conservation (PNC) due to the weak interaction is predicted to give rise to enantiomer dependent vibrational constants in chiral molecules, but the phenomenon has so far eluded experimental observation. The enhanced sensitivity of molecules to physics beyond the Standard Model (BSM), has led to substantial advances in molecular precision...

The isotopically chiral molecular ion CHDBrI$^+$ is identified as an exceptionally promising candidate for the detection of parity violation in vibrational transitions. The largest predicted parity-violating frequency shift reaches 1.8~Hz for the hydrogen wagging mode which has a sub-Hz natural line width and its vibrational frequency auspiciously...

Ion mobilities of Lr^+ (Z = 103) and of its lighter chemical homolog Lu^+ (Z = 71) in helium were calculated for the ground state ^1S_0 and the lowest metastable state ^3D_1. To this end we applied the multi-reference configuration interaction (MRCI) method to calculate the ion-atom interaction potentials in the different states. The Gram-Charlier...

We report measured and calculated values of radiative decay rates and vibrational branching fractions for the A$^2\Pi$ state of MgF. The decay rate measurements use time-correlated single photon counting with roughly 1% total uncertainty. Branching-fraction measurements are performed using two calibrated imaging systems to achieve few percent total...

We demonstrate a spin-precession method to observe and analyze multi-level coherence between all hyperfine levels in the $X ^2\Sigma^+,N=0$ ground state of barium monofluoride ($^{138}$Ba$^{19}$F). The signal is sensitive to the state-preparation Rabi frequency and external electric and magnetic fields applied in searches for a permanent electric d...

Molecules containing short-lived, radioactive nuclei are uniquely positioned to enable a wide range of scientific discoveries in the areas of fundamental symmetries, astrophysics, nuclear structure, and chemistry. Recent advances in the ability to create, cool, and control complex molecules down to the quantum level, along with recent and upcoming...

Four-component relativistic all-order multireference electron correlation approaches are the most accurate methods available for benchmark calculations of properties of heavy atoms and their compounds with complex (frequently quasi-degenerate) electronic shell structures. Benchmarking requires continued improvement of the relativistic Hamiltonian a...

High-precision tests of fundamental symmetries are looking for the parity- (P), time-reversal- (T) violating electric dipole moment of the electron (eEDM) as proof of physics beyond the Standard Model. Particularly, in polyatomic molecules, the complex vibrational and rotational structure gives the possibility to reach high enhancement of the P,T-o...

We present a theory-experiment investigation of the helically chiral compounds Ru(acac)3 and Os(acac)3 as candidates for next-generation experiments for detection of molecular parity violation (PV) in vibrational spectra. We used relativistic density functional theory calculations to identify optimal vibrational modes with expected PV effects excee...

In natural processes involving weak interactions, a violation of spatial parity conservation should appear. Its effects are expected to be observable in molecules using different spectroscopic methodologies, but due to the tiny magnitude of these effects they have never been measured yet. We present a theoretical analysis of four-component relativi...

High-precision tests of fundamental symmetries are looking for the parity- (P), time-reversal- (T) violating electric dipole moment of the electron (eEDM) as proof of physics beyond the Standard Model. Particularly, in polyatomic molecules, the complex vibrational and rotational structure gives the possibility to reach high enhancement of the P, T-...

Theoretical calculations based on the Dirac--Coulomb--Breit relativistic coupled cluster method have been carried out for the electron affinities and ionization potentials of the superheavy element nihonium (Nh) and its lighter homologues In and Tl. The In and Tl calculations are in agreement with measurement within uncertainties. For Nh, where exp...

We present an investigation of the performance of the relativistic multireference Fock-space coupled-cluster (FSCC) method for predicting molecular hyperfine structure (HFS) constants, including a thorough computational study to estimate the associated uncertainties. In particular, we considered the F19 HFS constant in the ground and excited states...

The four-component relativistic Dirac–Coulomb Hamiltonian and the multireference configuration interaction (MRCI) model were used to provide the reliable energy levels and spectroscopic properties of the Lr+ ion and the Lu+ homolog. The energy spectrum of Lr+ is very similar to that of the Lu+ homolog, with the multiplet manifold of the 7s2, 6d17s1...

Theoretical calculations based on the Dirac--Coulomb--Breit relativistic coupled cluster method have been carried out for the electron affinities and ionization potentials of the superheavy element nihonium (Nh) and its lighter homologues In and Tl. The In and Tl calculations are in agreement with measurement within uncertainties. For Nh, where exp...

We present an investigation of the performance of the relativistic multi-reference Fock-space coupled cluster (FSCC) method for predicting molecular hyperfine structure (HFS) constants, including a thorough computational study to estimate the associated uncertainties. In particular, we considered the $^{19}$F HFS constant in the ground and excited...

We present high-accuracy relativistic investigations of the spectrum of Lr, element 103, prompted by the planned optical spectroscopy experiments on this rare and short-lived atom. Reliable predictions of the transition lines are important for the planning and success of these challenging measurements. The relativistic coupled cluster approach was...

An investigation of a helically chiral compound Ru(acac)$_3$ shows its potential for the experimental detection of parity violation (PV) in a molecular system. An experiment measuring PV frequency shifts $\Delta \nu^\text{PV}$ in vibrational spectra of Ru(acac)$_3$ is being built at Laboratoire de Physique des Lasers in Paris. Based on our relativi...

The changes in the mean-square charge radius (relative to 209 Bi), magnetic dipole, and electric quadrupole moments of 187;188;189;191 Bi were measured using the in-source resonance-ionization spectroscopy technique at ISOLDE (CERN). A large staggering in radii was found in 187;188;189 Bi g , manifested by a sharp radius increase for the ground sta...

We report on the electrostatic trapping of neutral SrF molecules. The molecules are captured from a cryogenic buffer-gas beam source into the moving traps of a 4.5-m-long traveling-wave Stark decelerator. The SrF molecules in X^{2}Σ^{+}(v=0,N=1) state are brought to rest as the velocity of the moving traps is gradually reduced from 190 m/s to zero....

We present a four-component relativistic approach to describe the effects of the nuclear spin-dependent parity-violating (PV) weak nuclear forces on nuclear spin-rotation (NSR) tensors. The formalism is derived within the four-component polarization propagator theory based on the Dirac–Coulomb Hamiltonian. Such calculations are important for planni...

We report calculation of the energy spectrum and the spectroscopic properties of the superheavy element ion: Rf+. We use the four-component relativistic Dirac-Coulomb Hamiltonian and the multireference configuration interaction model to tackle the complex electronic structure problem that combines strong relativistic effects and electron correlatio...

We report calculation of the energy spectrum and the spectroscopic properties of the superheavy element ion: Rf^+. We use the 4-component relativistic Dirac-Coulomb Hamiltonian and the multireference configuration interaction (MRCI) model to tackle the complex electronic structure problem that combines strong relativistic effects and electron corre...

A measurement of the magnitude of the electric dipole moment of the electron (eEDM) larger than that predicted by the Standard Model (SM) of particle physics is expected to have a huge impact on the search for physics beyond the SM. Polar diatomic molecules containing heavy elements experience enhanced sensitivity to parity (P) and time-reversal (T...

We present high accuracy relativistic coupled cluster calculations of the first and second ionisation potentials and the electron affinity of the heaviest element in the Periodic Table, Og. The results were extrapolated to the basis set limit and augmented with the higher order excitations (up to perturbative quadruples), the Breit contribution, an...

A measurement of the magnitude of the electric dipole moment of the electron (eEDM) larger than that predicted by the Standard Model (SM) of particle physics is expected to have a huge impact on the search for physics beyond the SM. Polar diatomic molecules containing heavy elements experience enhanced sensitivity to parity ($P$) and time-reversal...

Planned optical spectroscopy experiments in lawrencium (Lr, Z = 103) require accurate theoretical predictions of the location of spectral lines in order to narrow the experimental search window. We present ab initio calculations of the atomic energy levels, transition amplitudes and g-factors for lawrencium, as well as its lighter homologue lutetiu...

A supersonic beam source for SrF and BaF molecules is constructed by combining the expansion of carrier gas (a mixture of 2% SF6 and 98% argon) from an Even-Lavie valve with laser ablation of a barium/strontium metal target at a repetition rate of 10 Hz. Molecular beams with a narrow translational velocity spread are produced at relative values of...

We present high accuracy relativistic coupled cluster calculations of the first and second ionization potentials and the electron affinity of the heaviest element in the periodic table, Og. The results were extrapolated to the basis set limit and augmented with the higher order excitations (up to perturbative quadruples), the Breit contribution, an...

Collinear laser spectroscopy measurements were performed on Ge69,71,73 isotopes (Z=32) at ISOLDE-CERN. The hyperfine structure of the 4s24p2P13→4s24p5sP1o3 transition of the germanium atom was probed with laser light of 269 nm, produced by combining the frequency-mixing and frequency-doubling techniques. The hyperfine fields for both atomic levels...

Measurements of nuclear spin-dependent parity-violating (NSD-PV) effects provide an excellent opportunity to test nuclear models and to search for physics beyond the Standard Model. Molecules possess closely spaced states with opposite parity which may be easily tuned to degeneracy to greatly enhance the observed parity-violating effects. A high-se...

This paper presents high-precision spectroscopic measurements of atomic tin using five different resonance-ionization schemes performed with the collinear resonance-ionization spectroscopy technique. Isotope shifts were measured for the stable tin isotopes from the 5s25p2P0,1,23 and 1S0 to the 5s25p6sP11,P1,23 and 5s25p7s1P1 atomic levels. The magn...

Collinear laser spectroscopy measurements were performed on $^{69,71,73}$Ge isotopes ($Z = 32$) at ISOLDE-CERN. The hyperfine structure of the $4s^2 4p^2 \, ^3P_1 \rightarrow 4s^2 4p 5s \, ^3P_1^o$ transition of the germanium atom was probed with laser light of 269 nm, produced by combining the frequency-mixing and frequency-doubling techniques. Th...

We discuss how molecule-based searches offer complementary probes to study the violation of fundamental symmetries. These experiments have the potential to probe not only the electron EDM, but also hadronic CPV phenomena. Future experimental developments will offer generic sensitivity to probe flavor neutral sources of both leptonic and hadronic CP...

We discuss how molecule-based searches offer complementary probes to study the violation of fundamental symmetries. These experiments have the potential to probe not only the electron EDM, but also hadronic CPV phenomena. Future experimental developments will offer generic sensitivity to probe flavor neutral sources of both leptonic and hadronic CP...

One of the most important properties influencing the chemical behavior of an element is the electron affinity (EA). Among the remaining elements with unknown EA is astatine, where one of its isotopes, ²¹¹At, is remarkably well suited for targeted radionuclide therapy of cancer. With the At⁻ anion being involved in many aspects of current astatine l...

Measurements of nuclear spin-dependent parity-violating (NSD-PV) effects provide an excellent opportunity to test nuclear models and to search for physics beyond the Standard Model. Molecules possess closely-spaced states with opposite parity which may be easily tuned to degeneracy to greatly enhance the observed parity-violating effects. A high-se...

We report a methodology that allows the investigation of the consequences of the spin–orbit coupling by means of the QTAIM and ELF topological analyses performed on top of relativistic and multiconfigurational wave functions. In practice, it relies on the “state‐specific” natural orbitals (NOs; expressed in a Cartesian Gaussian‐type orbital basis)...

Accurate predictions of hyperfine structure (HFS) constants are important in many areas of chemistry and physics, from the determination of nuclear electric and magnetic moments to benchmarking of new theoretical methods. We present a detailed investigation of the performance of the relativistic coupled cluster method for calculating HFS constants...

Nuclear magnetic quadrupole moments (MQMs), such as intrinsic electric dipole moments of elementary particles, violate both parity and time-reversal symmetry and, therefore, probe physics beyond the standard model. We report on accurate relativistic coupled cluster calculations of the nuclear MQM interaction constants in BaF, YbF, BaOH, and YbOH. W...

One of the most important properties influencing the chemical behavior of an element is the energy released with the addition of an extra electron to the neutral atom, referred to as the electron affinity (EA). Among the remaining elements with unknown EA is astatine, the purely radioactive element 85. Astatine is the heaviest naturally occurring h...

Accurate predictions of hyperfine structure (HFS) constants are important in many areas of chemistry and physics, from the determination of nuclear electric and magnetic moments to benchmarking of new theoretical methods. We present a detailed investigation of the performance of the relativistic coupled cluster method for calculating HFS constants...

Nuclear magnetic quadrupole moments (MQMs), like intrinsic electric dipole moments of elementary particles, violate both parity and time-reversal symmetry and therefore probe physics beyond the Standard Model of particle physics. We report on accurate relativistic coupled cluster calculations of the nuclear MQM interaction constants in BaF, YbF, Ba...

Recent theoretical works have proposed atomic clocks based on narrow optical transitions in highly charged ions. The most interesting candidates for searches of physics beyond the Standard Model are those which occur at rare orbital crossings where the shell structure of the periodic table is reordered. There are only three such crossings expected...

The planned measurement of optical resonances in singly ionized lawrencium (Z=103) requires accurate theoretical predictions to narrow the search window. We present high-precision, ab initio calculations of the electronic spectra of Lr+ and its lighter homologue lutetium (Z=71). We have employed the state-of-the-art relativistic Fock space coupled...

Time-resolved detection of laser-induced fluorescence from pulsed excitation of electronic states in barium monofluoride (BaF) molecules has been performed in order to determine the lifetimes of the A2Π1/2 and A2Π3/2 states. The method permits control over experimental parameters such that systematic biases in the interpretation of the data can be...

Recent theoretical works have proposed atomic clocks based on narrow optical transitions in highly charged ions. The most interesting candidates for searches of new physics are those which occur at rare orbital crossings where the shell structure of the periodic table is reordered. There are only three such crossings expected to be accessible in hi...

Scalar and spin-dependent relativistic effects can influence the geometries and wave functions of the ground and excited states of molecular systems in a way that is not always trivial. However, it is still common for researchers, in particular within the quantum chemistry community, to neglect the spin-dependent effects while discussing the bindin...