A5040188256- Advanced Chemical Physics Studies
- Inorganic Fluorides and Related Compounds
- Atomic and Molecular Physics
- Atomic and Subatomic Physics Research
- Molecular Spectroscopy and Structure
- Cold Atom Physics and Bose-Einstein Condensates
- Spectroscopy and Laser Applications
- Atmospheric Ozone and Climate
- X-ray Spectroscopy and Fluorescence Analysis
- Solid-state spectroscopy and crystallography
- Mass Spectrometry Techniques and Applications
- Electron and X-Ray Spectroscopy Techniques
- Crystallography and molecular interactions
- Advanced Frequency and Time Standards
- High-pressure geophysics and materials
- Quantum, superfluid, helium dynamics
- Astro and Planetary Science
- X-ray Diffraction in Crystallography
- Spectroscopy and Quantum Chemical Studies
- Astrophysics and Cosmic Phenomena
- Neutrino Physics Research
- Dark Matter and Cosmic Phenomena
- Quantum optics and atomic interactions
- Analytical Chemistry and Sensors
- Crystallization and Solubility Studies
Pomona College
2011-2024
Leibniz University Hannover
2013-2019
Arizona State University
2019
East China Normal University
2019
Jet Propulsion Laboratory
1985-2011
University of Edinburgh
2007
California Institute of Technology
1991
Queen's University Belfast
1991
Philipps University of Marburg
1984-1986
The University of Texas at Austin
1983-1985
Static electric dipole moments of nondegenerate systems probe mass scales for physics beyond the Standard Model well those reached directly at high energy colliders. Discrimination between different models, however, requires complementary searches in atomic-molecular-and-optical, nuclear and particle physics. In this report, we discuss current status prospects near future a compelling suite such experiments, along with developments needed encompassing theoretical framework.
Monomers and dimers of the four alkali chlorides NaCl, KCl, RbCl, CsCl have been studied in vapor phase using counting method high energy electron diffraction. Nozzle temperatures from 840–960 K were required to achieve necessary pressures approximately 0.01 Torr. Large mean amplitudes vibration (as big as 0.26 Å) similarity monomer dimer bonded distances complicate analysis, although refined structures yield good fits data, especially for stronger scatterers RbCl CsCl. Using harmonic...
The molecular structures of Se(SCH3)2 and Te(SCH3)2 were investigated using gas-phase electron diffraction (GED) ab initio DFT geometry optimisations. While parameters involving H atoms refined flexible restraints according to the SARACEN method, that depended only on heavy could be without restraints. GED-determined geometric (rh1) are: rSe–S 219.1(1), rS–C 183.2(1), rC–H 109.6(4) pm; ∠S–Se–S 102.9(3), ∠Se–S–C 100.6(2), ∠S–C–H (mean) 107.4(5), ϕS–Se–S–C 87.9(20), ϕSe–S–C–H 178.8(19)° for...
A novel method has been developed to allow the accurate determination of equilibrium gas-phase structures from experimental data, thus allowing direct comparison with theory. This new is illustrated through example sodium chloride vapor at 943 K. Using this approach monomer (NaCl) and dimer (Na(2)Cl(2)), together fraction existing as dimer, have determined by electron diffraction supplemented data microwave spectroscopy ab initio calculations. Root-mean-square amplitudes vibration (u)...
The sensitivity of the PbF molecule to electron electric dipole moment has motivated detailed microwave spectroscopy. Previous theoretical approaches cannot fully explain spectra. In turn, explanation from ``first principles'' is very important both for molecular theory and confirmation correctness interpretation experimental data obtained with high precision. All these issues are decisively addressed here. We have determined centrifugal correction parameters hyperfine structure constants,...
Differential electron scattering cross sections have been measured for dipole-forbidden and resonance transitions in Mg II, Zn II Cd the angular range 4 degrees <or= theta <or=17 at 50 eV. These provide first recorded distributions an optically forbidden transition. It is found that while section excitation of 4s 2S to 3d94s2 2D transition small, those 3s 3d 2D, (unresolved lines) 5s 4d95s2 are comparable magnitude with excitation. In addition, one finds allowed very similar distributions,...
Reported herein are measured absolute single, double, and triple charge exchange (CE) cross sections for the highly charged ions (HCIs) ${\mathrm{C}}^{q+}$ $(q=5,6)$, ${\mathrm{O}}^{q+}$ $(q=6,7,8)$, ${\mathrm{Ne}}^{q+}$ $(q=7,8)$ colliding with molecular species ${\mathrm{H}}_{2}\mathrm{O}$, CO, $\mathrm{C}{\mathrm{O}}_{2}$. Present data can be applied to interpreting observations of x-ray emissions from comets as they interact solar wind. As such, ion impact energies...
Pure rotational spectra of the ground electronic-vibrational ${X}_{1}$ state ${}^{204}$Pb${}^{19}$F, ${}^{206}$Pb${}^{19}$F, ${}^{207}$Pb${}^{19}$F, and ${}^{208}$Pb${}^{19}$F are measured with a resonator pulsed supersonic jet Fourier-transform microwave spectrometer. Also reported is new measurement Stark effect on optical $A\ensuremath{\leftarrow}{X}_{1}$ transitions. These combined published high-resolution infrared ${X}_{2}\ensuremath{\leftrightarrow}{X}_{1}$ transitions in order to...
Electron-excitation cross sections are reported for the 3s $^{2}$S\ensuremath{\rightarrow}3p $^{2}$P(h,k) resonance transition in ${\mathrm{Mg}}^{+}$ at energies from threshold (4.43 eV) to approximately 9 times (40.0 eV). The electron-energy-loss merged-beams technique used these measurements is described detail. In addition, method of separating contributions elastically scattered (Coulomb) and inelastically electrons present case previously ${\mathrm{Zn}}^{+}$ results [Phys. Rev. Lett....
A new high-temperature nozzle has been added to our counting electron diffraction apparatus, enabling precise studies of the vibrationally averaged structure molecules at temperatures between 300 and 1000 K. Our results for CO2 are compared with harmonic theory recent variational wave function calculation Kohl Hilderbrandt. The system is described, differences data theories discussed.
Absolute cross sections are reported for single, double, and triple charge exchange of Fe${}^{q}$${}^{+}$ ($q=5--13$) ions with CO CO${}_{2}$. The highly charged Fe generated in an electron cyclotron resonance ion source. data derived from knowledge the target gas pressure, path length, incident charge-exchanged currents. Experimental results compared new calculations these $n$-electron classical trajectory Monte Carlo approximation which ensuing radiative nonradiative cascades approximated...
Absolute single- and double-charge-exchange cross sections for the astrophysically prominent ${\mathrm{O}}^{6+}$ ion with atomic molecular targets He ${\mathrm{H}}_{2}$ are reported. These collisions give rise to x-ray emissions in interplanetary medium, planetary atmospheres, comets as they approach sun. Measurements have been carried out using Caltech Jet Propulsion Laboratory electron cyclotron resonance source at energies of 1.17 2.33 keV/u characteristic slow fast components solar wind....
Absolute, cascade-free excitation cross sections in an ion have been measured for the resonance $^{2}$S${\ensuremath{\rightarrow}}^{2}$P transition ${\mathrm{Zn}}^{+}$ using electron-energy-loss and merged electron-ion beams methods. Measurements were carried out at electron energies of below threshold to 6 times threshold. Comparisons are made with 2-, 5-, 15-state close-coupling distorted-wave theories. There is good agreement between experiment over energy range calculations.
Charge exchange (also referred to also charge transfer or electron capture) has been studied by the atomic collisions community for many years. Apart from fundamental interest in subject, much of research driven needs fusion where it plays an important role radiative heat loss and diagnostics tokamak plasmas. It is therefore surprising that generally not applied as extensively astrophysical Atomic data astrophysics includes comprehensive process but little exchange, due fact does exist...
Here we report precision microwave spectroscopy of pure rotational transitions the $^{207}\mathrm{Pb}$$^{19}\mathrm{F}$ isotopologue. We use these data to make predictions sensitivity molecule $P$-odd, $T$-even and $T$-odd effects.
We report the results of our theoretical study and analysis earlier experimental data for g-factor tensor components ground $^2\Pi_{1/2}$ state free PbF radical. The values obtained both within relativistic coupled-cluster method combined with generalized effective core potential approach fit from [R.J. Mawhorter, B.S. Murphy, A.L. Baum, T.J. Sears, T. Yang, P.M. Rupasinghe, C.P. McRaven, N.E. Shafer-Ray, L.D. Alphei, J.-U. Grabow, Phys. Rev. A 84, 022508 (2011); A. thesis, Pomona College,...
Results are presented from ab initio calculations on the symmetrical alkali halide dimers made up of Li, Na, K, F, and Cl. We examine sensitivity representative monomer dimer geometries to variation basis set with without polarization diffuse functions. The then compared available experimental results. have also calculated vibrational frequencies at restricted Hartree–Fock level examined changes in geometry brought about by correlation using second-order Mo/ller–Plesset perturbation theory....
The fine and hyperfine interactions in $X{}^{2}{\mathrm{\ensuremath{\Sigma}}}^{+}(v=0)$ ${A}^{2}{\mathrm{\ensuremath{\Pi}}}_{1/2}(v=0)$ states of $^{173}\mathrm{YbF}$ have been characterized using a combination high-resolution laser-induced fluorescence spectroscopy the $A{}^{2}{\mathrm{\ensuremath{\Pi}}}_{1/2}$\ensuremath{-}$X{}^{2}{\mathrm{\ensuremath{\Sigma}}}^{+}$ (0,0) electronic transition ground-state microwave spectroscopy. Fourteen frequencies associated with...
The ab initio Hartree–Fock calculation of the elastic electron scattering cross section sulphur hexafluoride is reported. integrals for Born amplitudes have been evaluated by a new simple technique, based on Gaussian quadrature. Spherical averaging was performed numerically; different techniques spherical are discussed. An estimated re structure used and vibrational effects neglected. In order to assess effect basis set intensities, calculations nitrogen molecule with six sets. Using these...
We report calculations on the q(Yb) electric field gradient (EFG) for X2Σ+ and A2Π1/2 electronic states of ytterbium monofluoride (YbF) molecule at molecular mean-field Dirac–Coulomb–Gaunt as well scalar-relativistic coupled-cluster levels theory using large uncontracted basis sets. Vibrational contributions are included in final results. Our estimated nuclear quadrupole coupling constants –3386(78) MHz –2083(153) 173YbF stark contrast to only available experimental results (–2050(170)...
In semiempirical ionic models a number of adjustable parameters have to be fitted experimental data either monomer molecules or crystals. This leads strong correlations between these constants and prevents unique test clear physical interpretation the fit parameters. Moreover, it is not whether remain unchanged when model applied dimers larger clusters. It shown that can substantially reduced reliable information about available from experiments ab initio calculations. Starting with Dunham...
Within the independent atom scattering model, we derive an approximate formula for rotationally and vibrationally averaged three-atom terms in series expansion of electron cross section. This uses atomic factors as well scattered wavefunctions input, rotational averaging is performed numerically. We compare our results to previous theoretical multiple approaches molecules F(3), F(4), SF(6) experimental data TeF(6). Our are consistent with those calculations inclusion term produces a...