Hyperfine Multiplet Research Articles

Computation of hyperfine multiplet oscillator strengths in Tantalum atom

BackgroundThe electronic transitions between two fine levels depend on the transition probability. The transition probability depends on spectral line strength and oscillator strength. The oscillator strength depends on the number of oscillators and their energies. In this research, we will find the oscillator strengths of hyperfine multiplets of the Tantalum atom. The oscillator strength of hyperfine multiplet investigation aims to enhance our understanding of Tantalum's spectral characteristics. This work provides valuable information in the spectroscopy of material, atomic/molecular, and astrophysics.ResultFourier transform spectra from ultraviolet to far infrared regions have been obtained from TUGRAZ. Fourier transform spectra give the most reliable position of the wavelength of hyperfine multiplets. The Fourier transform spectra of Tantalum contain thousands of Tantalum I and II spectral lines. Each spectral line can be characterized by its upper and lower levels and corresponding angular momenta and hyperfine constants. These properties of the spectral lines were collected from the literature. Hyperfine multiplets for each fine structure were calculated, and they revealed their spectroscopic behavior with high precision.ConclusionIn this study, Tantalum's hyperfine multiplet oscillator strength was calculated using advanced computational techniques to address its atomic structure. The fine structure “gf” values were obtained from literature, and intensities of the multiplets were determined. They combined with the gf values to calculate the oscillator strengths of the hyperfine multiplets.

The nitrogen isotopic ratio of HC3N towards the L1544 prestellar core

The origin of the heavily fractionated reservoir of nitrogen in comets remains an issue in the theory of their formation and hence of the solar system. Whether the fractionated reservoir traced by comets is inherited from the interstellar cloud or is the product of processes taking place in the protostar, or in the protoplanetary disk, remains unclear. So far, observations of nitrogen isotopic ratios in protostars or prestellar cores have not securely identified such a fractionated reservoir owing to the intrinsic difficulty of direct isotopic ratios measurements. In this article, we report the detection of 5 rotational lines of \ce{HC3N}, {including the weaker components of the hyperfine multiplets}, and two rotational lines of its $^{15}$N isotopologue, towards the L1544 prestellar core. Based on a MCMC/non-LTE multi-line analysis at the hyperfine level, we derive the column densities of \ce{HC3N} ($8.0\pm0.4\tdix{13}$\cc) and \ce{HC3^{15}N} ($2.0\pm0.4\tdix{11}$\cc) and derive an isotopic ratio of 400$\pm$20(1$\sigma$). This value suggests that \ce{HC3N} is slightly depleted in $^{15}$N in L1544 with respect to the elemental $^{14}$N/$^{15}$N ratio {of $\approx$330} in the present-day local interstellar medium. Our study also stresses the need for radiative calculations at the hyperfine level. Finally, the comparison of the derived ratio with those obtained in CN and HCN in the same core seems to favor CN+C$_2$H$_2$ as the dominant formation route to HC$_3$N. However, uncertainties in the isotopic ratios preclude definitive conclusions.

ALMA imaging of C2H emission in the disk of NGC 1068

We study the feedback of star formation and nuclear activity on the chemistry of molecular gas in NGC1068, a nearby (D=14Mpc) Seyfert 2 barred galaxy, by analyzing if the abundances of key molecular species like ethynyl (C2H), a classical tracer of PDR, change in the different environments of the disk of the galaxy. We have used ALMA to map the emission of the hyperfine multiplet of C2H(N=1-0) and its underlying continuum emission in the central r~35"(2.5kpc)-region of the disk of NGC1068 with a spatial resolution 1.0"x0.7"(50-70pc). We have developed a set of time-dependent chemical models to determine the origin of the C2H gas. A sizeable fraction of the total C2H line emission is detected from the r~1.3kpc starburst (SB) ring. However, the brightest C2H emission originates from a r~200pc off-centered circumnuclear disk (CND), where evidence of a molecular outflow has been previously found in other molecular tracers imaged by ALMA. We also detect significant emission that connects the CND with the outer disk. We derived the fractional abundances of C2H (X(C2H)) assuming LTE conditions. Our estimates range from X(C2H)~a few 10^-8 in the SB ring up to X(C2H)~ a few 10^-7 in the outflow region. PDR models that incorporate gas-grain chemistry are able to account for X(C2H) in the SB ring for moderately dense (n(H2)>10^4 cm^-3) and moderately UV-irradiated gas (UV-field<10xDraine field) in a steady-state regime. However, the high fractional abundances estimated for C2H in the outflow region can only be reached at very early times (T< 10^2-10^3 yr) in models of UV/X-ray irradiated dense gas (n(H2)>10^4-10^5) cm^-3). We interpret that the transient conditions required to fit the high values of X(C2H) in the outflow are likely due to UV/X-ray irradiated non-dissociative shocks associated with the highly turbulent interface between the outflow and the molecular gas in NGC1068.

Are infrared dark clouds really quiescent?

The dense, cold regions where high-mass stars form are poorly characterised, yet they represent an ideal opportunity to learn more about the initial conditions of high-mass star formation (HMSF), since high-mass starless cores (HMSCs) lack the violent feedback seen at later evolutionary stages. We present continuum maps obtained from the Submillimeter Array (SMA) interferometry at 1.1 mm for four infrared dark clouds (IRDCs, G28.34S, IRDC 18530, IRDC 18306, and IRDC 18308). We also present 1 mm/3 mm line surveys using IRAM 30 m single-dish observations. Our results are: (1) At a spatial resolution of 10^4 AU, the 1.1 mm SMA observations resolve each source into several fragments. The mass of each fragment is on average >10 Msun, which exceeds the predicted thermal Jeans mass of the whole clump by a factor of up to 30, indicating that thermal pressure does not dominate the fragmentation process. Our measured velocity dispersions in the 30 m lines imply that non-thermal motions provides the extra support against gravity in the fragments. (2) Both non-detection of high-J transitions and the hyperfine multiplet fit of N2H+(1-0), C2H(1-0), HCN(1-0), and H13CN(1-0) indicate that our sources are cold and young. However, obvious detection of SiO and the asymmetric line profile of HCO+(1-0) in G28.34S indicate a potential protostellar object and probable infall motion. (3) With a large number of N-bearing species, the existence of carbon rings and molecular ions, and the anti-correlated spatial distributions between N2H+/NH2D and CO, our large-scale high-mass clumps exhibit similar chemical features as small-scale low-mass prestellar objects. This study of a small sample of IRDCs illustrates that thermal Jeans instability alone cannot explain the fragmentation of the clump into cold (~15 K), dense (>10^5 cm-3) cores and that these IRDCs are not completely quiescent.

Atomic-like spin noise in solid-state demonstrated with manganese in cadmium telluride.

Spin noise spectroscopy is an optical technique which can probe spin resonances non-perturbatively. First applied to atomic vapours, it revealed detailed information about nuclear magnetism and the hyperfine interaction. In solids, this approach has been limited to carriers in semiconductor heterostructures. Here we show that atomic-like spin fluctuations of Mn ions diluted in CdTe (bulk and quantum wells) can be detected through the Kerr rotation associated to excitonic transitions. Zeeman transitions within and between hyperfine multiplets are clearly observed in zero and small magnetic fields and reveal the local symmetry because of crystal field and strain. The linewidths of these resonances are close to the dipolar limit. The sensitivity is high enough to open the way towards the detection of a few spins in systems where the decoherence due to nuclear spins can be suppressed by isotopic enrichment, and towards spin resonance microscopy with important applications in biology and materials science.

Microwave spectrum, structure, tautomeric, and conformational composition of 4-vinylimidazole

The microwave spectra of the two conformers each, of the 1H and 3H tautomers of 4-vinylimidazole, have been measured in the 48-72 GHz spectral region. The 4-vinylimidazole was generated in situ by the facile decarboxylation of urocanic acid at its vaporization temperature of 220 °C. The recognition of this reaction casts doubt on the reliability of a previous published spectroscopic study apparently mistakenly thought to be of uncontaminated vaporized urocanic acid, a natural product of great interest in skin cancer etiology. Quantum chemical theoretical predictions of the structures of each of ten possible conformers∕tautomers of urocanic acid and four of 4-vinylimidazole were performed at the ab initio MP2∕cc-pVTZ level, with vibrational predictions at the B3LYP∕cc-pVTZ and M062X∕cc-pVTZ levels. The predicted values of rotational constants for all the urocanic acid species were found to be quite inconsistent with those of the four observed spectra. For the 4-vinylimidazole isomers, the calculated relative energies suggested that all four species would have substantial equilibrium mole fractions at 220 °C. The isomers were identified by matching the observed and calculated rotational constants. The resulting assignment was found to be consistent with the predicted and observed (14)N nuclear quadrupole hyperfine multiplet patterns for a suitable rotational transition, and with the observed versus empirically calculated inertial defects. With one exception, the predicted structures were found to be planar. Resembling the case of 1-vinylimidazole, where one conformer is nonplanar, one isomer of 4-vinylimidazole was found to be quasiplanar. This seems to belong to a class of spontaneous symmetry-breaking observed in the molecular structure of some otherwise planar vinyl aromatic compounds.

High-resolution synchrotron-based Fourier transform spectroscopy of in the 120–350 cm−1 far-infrared region

The Fourier transform spectrum of the isotopologue of methanol has been recorded in the 120–350 cm−1 far-infrared region at a resolution of 0.00096 cm−1 using synchrotron source radiation at the Canadian Light Source. The study, motivated by astrophysical applications, is aimed at generating a sufficiently accurate set of energy level term values for the ground vibrational state to allow prediction of the centres of the quadrupole hyperfine multiplets for astronomically observable sub-millimetre transitions to within an uncertainty of a few MHz. To expedite transition identification, a new function was added to the Ritz program in which predicted spectral line positions were generated by an adjustable interpolation between the known assignments for the and isotopologues. By displaying the predictions along with the experimental spectrum on the computer monitor and adjusting the predictions to match observed features, rapid assignment of numerous sub-bands was possible. The least squares function of the Ritz program was then used to generate term values for the identified levels. For each torsion-K-rotation substate, the term values were fitted to a Taylor-series expansion in powers of J(J + 1) to determine the substate origin energy and effective B-value. In this first phase of the study we did not attempt a full global fit to the assigned transitions, but instead fitted the sub-band J-independent origins to a restricted Hamiltonian containing the principal torsional and K-dependent terms. These included structural and torsional potential parameters plus quartic distortional and torsion–rotation interaction terms.

Effects of collisional interference of lines in the spectra of symmetric top molecules: III. Broadening of rotational transitions with a hyperfine structure

The peculiarities of the broadening of rotational transitions of molecules in the case where the spectrum exhibits a hyperfine structure caused by the nuclear quadrupole interaction are considered. The relaxation parameters of the components of a number of hyperfine multiplets of CH3I molecules are calculated taking into account self-broadening, and calculations are compared with experiment.

Laser-microwave spectroscopy of Cu I atoms in S, P, D, F and G Rydberg states

Energy-level positions of neutral copper atoms in S, P, D, F and G Rydberg series for principal quantum number n = 23–38 have been determined with sub-MHz accuracy by means of laser-microwave spectroscopy in the 73–321 GHz frequency range. Quantum defects of L = 0–4 levels and fine-structure splittings of P, D, F and G levels have been found from a global analysis of the measured frequencies of 79 single- and two-photon resonance transitions. Hyperfine multiplets were observable in several cases below n = 30 whose splitting frequencies are consistent with n−3 scaling from low-lying levels. An improved value of the Cu I ionization potential 62 317.46 ± 0.03 cm−1 has been obtained.

Correlation between electron paramagnetic resonance and thermoluminescence in natural sodalite

Samples of natural sodalite, Na8Al6Si6O24Cl2, submitted to gamma irradiation and to thermal treatments, have been investigated using the thermoluminescence (TL) and electron paramagnetic resonance (EPR) techniques. Both, natural and heat-treated samples at 500°C in air for 30 min, present an EPR signal around g = 2.01132 attributed to oxygen hole centers. The EPR spectra of irradiated samples show an intense line at g = 2.0008 superimposed by a hyperfine multiplet of 11 lines due to an O− ion in an intermediate position with respect to two adjacent Al nuclei. In the TL measurements, the samples were annealed at 500°C for 30 min and then irradiated with γ doses varying from 0.001 to 20 kGy. All the samples have shown TL peaks at 110, 230, 270, 365, and 445°C. A correlation between the EPR g = 2.01132 line and the 365°C TL peak was observed. A TL model is proposed in which a Na+ ion acts as a charge compensator when an Al3+ ion replaces a Si4+ lattice ion. The γ ray destruction of the Al–Na complex provides an electron trapped at the Na and a hole trapped at a non-bridging oxygen ion adjacent to the Al3+ ion.

Magnetic resonance reversals in optically pumped alkali-metal vapor

We report an unusual phenomenon, peculiar sign reversals of the ground-state magnetic resonances and of the zero-dip resonance (Zeeman resonance at zero field) of optically pumped, alkali-metal vapors. These anomalies occur when a weak circularly polarized $D1$ laser light is tuned to pump atoms predominantly from the lower ground-state hyperfine multiplet. One can understand the signal reversals in a simple, semiquantitative way with reference to the spin-temperature distribution. Quantitative computer simulations are in excellent agreement with observations.

Sum rules for an atomic hyperfine structure in a magnetic field

The sum rules for the energy levels of a hyperfine multiplet in a constant uniform magnetic field are presented. It is found that for any value of the electron angular moment and the nuclear spin there are certain linear combinations of energy levels that do not depend on the magnetic field and can be used to determine the unperturbed hyperfine-structure separation in the presence of a perturbing magnetic field. It is also demonstrated that there are other linear combinations that are linear with the external magnetic field and hence can be used to determine bound values of the electron and nuclear magnetic moments. The accuracy of the approximation within which the result is valid is also discussed.PACS Nos.: 32.10.Fn, 32.60.+i1

Multiple scattering of photons by atomic hyperfine multiplets

Mesoscopic interference effects in multiple scattering of photons depend crucially on the internal structure of the scatterers. In the present paper, we develop the analytical theory of multiple photon scattering by cold atoms with arbitrary internal hyperfine multiplets. For a specific application, we calculate the enhancement factor of elastic coherent backscattering as a function of detuning from an entire hyperfine multiplet of neighboring resonances that cannot be considered isolated. Our theory permits one to understand why atoms behave differently from classical Rayleigh point-dipole scatterers, and how the classical description is recovered for larger but still microscopic objects like molecules or clusters.

Determination of a transmembrane pH difference in chloroplasts with a spin label tempamine

We present a method for measuring the transmembrane pH difference (ΔpH=pH in−pH out) in chloroplasts with a spin label TEMPAMINE (4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl) accumulating inside the thylakoids in response to generation of ΔpH. Experiments with chloroplasts suspended in the media of different osmolarity demonstrated that most of TEMPAMINE (TA) molecules taken up by chloroplasts were localized in the bulk of the thylakoid lumen. The ΔpH value was determined from the relationship ΔpH=lg([H +] in/[H +] out)≅lg( C in/ C out), where C in and C out are the concentrations of TA inside and outside the thylakoids, respectively. To quantify the internal concentration C in, we used the threshold nature of the concentration-dependent broadening of the EPR signal from TA. It was demonstrated that spin-exchange interactions between TA molecules caused an observable broadening of the signal only when the concentration of TA exceeded the threshold level, [ TA] ϑ≈2.0–2.2 mM . The concentration dependencies of the signal parameters (the peak-to-peak amplitude, A pp, and the linewidth, Δ H pp) were described within a model of the non-homogeneous broadening of an unresolved hyperfine multiplet from the protons of TA molecule. If the concentration of TA inside the thylakoids went beyond the threshold level, the spin-exchange broadening of the EPR signal was accompanied by a reversible decrease in the signal height (parameter Δ A). By measuring the signal behavior at different levels of microwave power, we were able to discriminate between the line broadening effects caused by concentrating TA molecules inside the thylakoids or the light-induced changes in the concentration of oxygen. We developed a general algorithm for determination of the ΔpH value and the internal volume of thylakoids, V in, from the non-linear dependence of parameter Δ A on the concentration C 0 of TA in a chloroplast suspension. Advantages of this method are: (i) it avoids the use of a broadening agent; (ii) it allows the internal volume of thylakoids to be evaluated; and (iii) the concentrations of TA used to measure the ΔpH are below the range of concentrations that could cause the uncoupling electron transport to ATP synthesis in chloroplasts. Results of our measurements are consistent with the literature data on ΔpH determinations by other methods.

Transfer of Precessing Spin Polarizations between Different Kinds of Atoms with Sameg-Factor

In spin-related fundamental researches, there have been considerable interests in the transfer of microscopic orders between magnetic sublevels of different kinds of atoms. As for gaseous atomic systems, collisional transfer of spin polarization from optically pumped atoms A to atoms B is attained through spin exchange collisions. So far many experiments have been reported on the transfer of longitudinal spin polarization created along a static magnetic field. Transfer of coherence, on the other hand,is possible only when the energy matching condition j!A !Bj < is satisfied, where !A and !B are the Larmor frequencies of atoms A and B, and the line width. This is the reason why transfer of spin polarization precessing around the static magnetic field has not been observed except for a few experiments; The coherence transfer has been observed in the experiments where the atoms are subjected to properly chosen rf magnetic fields. Recently, it has been reported that coherence transfer between different kinds of atoms is possible by using the light field which transversely pumps only one kind of atoms under properly chosen experimetal conditions. It has also been pointed out that, as for the system of Rb and K atoms, which happen to have the same gyro-magnetic ratio, the peculier distortion of the magnetic resonance signal line shapes observed in the collisionally pumped atoms can be explained by the spin exchange coupling between the resonant Rb and K atoms. It is suggested that the precessing spin polarization in Rb can be transferred to K atoms or vice versa, since their Zeeman splittings become equal in the hyperfine multiplets jF 1⁄4 1i and jF 1⁄4 2i of the ground state 2S1=2 with the same gyromagnetic ratio 1⁄4 2 700 kHz/G. The experimental apparatus of the present experiment is shematically shown in Fig. 1. In addition to a droplet of natural rubidium and potassium, the sample cell contains 50mbar Ar as a buffer gas. It is subjected to a static magnetic field of H0 1⁄4 0:786G along the z axis and irradiated transversely to the field by a light beam from a GaAlAs laser A (output power = 10mW, beam diameter = 1mm). It is left-handed circularly polarized and tuned to the Rb absorption lines (S1=2, F 1⁄4 1 ! P1=2, F 1⁄4 1 and 2) which are not resolved owing to the Doppler broadening. The intensity of the laser A is modulated by an AOM (acousto-optic-modulator) at the Larmor frequency !A 1⁄4 2 550 (1⁄4 700 0:786) kHz of Rb in a rectangular shape pulse. As mentioned above the precessing spin polarization in Rb can be transferred to K. The precessing spin polarization of Rb and that of K are detected from the Faraday rotations of the beams of probe lasers B ( 1⁄4 794 nm, output power = 3mW, beam diameter = 2mm) and C ( 1⁄4 769 nm, output power = 3mW, beam diameter = 2mm), respectively. The frequency of laser B is chosen to be a few GHz higher than the Rb absorption lines (S1=2, F 1⁄4 1 ! P1=2, F 1⁄4 1 and 2) to prevent the detection beam from destroying the polarization. Similarly, the frequency of laser C is chosen to be a few GHz higher than the K absorption lines (S1=2, F 1⁄4 1 and 2 ! P1=2, F 1⁄4 1 and 2) which are not resolved owing to the Doppler broadening. They are linearly polarized and counter-propagated against the pumping beam,making angles of about 1 to the pumping beam. In each case the transmitted light beam of probe laser passes through the analyzer which makes an angle 45 to the polarization of the incident beam,and then it is detected by a pin-photo diode. The signals are electronically averaged over a few hundred cycles. Figure 2(a) shows the typical examples of signals on the magnetizations M x and M B x of Rb and K, respectively, Fig. 1. Schematic diagram of the experimetal apparatus. AOM, acoustooptic modulator; PD, pin-photo diode; P, polarizer; A, analyzer.

Detection of low magnetic field by means of nuclear resonance of beats

The possibilities of detection of low magnetic fields by means of nuclear resonance of beats are discussed. It is shown that when low-frequency coherence is introduced into a system consisting of an arbitrary number of hyperfine sublevels of the atom's excited states in presence of an external magnetic field, in the high-temperature approximation and taking into account the dipole and quadrupole effects only, a complicated energy structure of hyperfine multiplets doesn't influence the dynamics of transverse components of nuclear magnetization. These occur to be just the same as in the case of two-level system. The multilevel feature of the spin system is not responsible for the fact of absence of the saturation phenomena on nuclear resonance of beats, which is characteristic of all the types of resonance of beats.

Towards synthetic models for trinuclear copper active sites of ascorbate oxidase and laccase: self-assembly, crystal structure and magnetic properties of the copper(II) complexes of 1,3,5-tris(1,4,7-triazacyclonon-1-ylmethyl)benzene †

Reaction of the hydrobromide salt of 1,3,5-tris(1,4,7-triazacyclonon-1-ylmethyl)benzene, L·9HBr, with copper(II) nitrate followed by cation-exchange chromatographic purification afforded [Cu3L(H2O)6][ClO4]6·6H2O 1. The ESR and magnetic susceptibility data indicated that the complex consists of three identical non-interacting copper(II) centres. Reaction of 1 with a phosphate source produces {[Cu3L(µ-OH)(µ3-HPO4)(H2O)][PF6]3·3H2O}n2 the polymeric lattice of which contains trinuclear copper(II) sites with structural similarities to laccase (Lc) and ascorbate oxidase (AO). These trinuclear sites consist of two type 3 copper(II) centres, at a separation of 3.557(4) A, linked by an hydroxo bridge and two phosphate oxygens while another phosphate oxygen links these two centres to the further removed type 2 copper(II) centre, establishing separations of 4.561(4) and 5.474(4) A. The magnetic properties of 2 were investigated in the temperature range 4.2–300 K and they revealed an S = ½ molecular ground state arising from antiferromagnetic coupling. A number of models have been employed in order quantitatively to fit the µeffversus temperature data including those applicable to the resting oxidised state of laccase and ascorbate oxidase, vis-a-vis dimer plus uncoupled monomer, but the best fits were obtained using a symmetrical trinuclear approximation with J12 for the doubly bridged [CuL(µ-OH)(µ-HPO4)Cu] moiety of –53 or ca. –80 cm–1 combined respectively with J for the two equal three-atom phosphato bridges of –90 or –77 to –90 cm–1. The 77 K solid-state ESR spectrum of 2 is unusual for S = ½ ground-state systems and shows six components of a probable seven-line copper hyperfine multiplet between 2500 and 3100 G and a strong x, y resonance at ca. 3200 G, most probably due to weak copper(II) pair interactions or the superimposition of S = ½ signals from both molecular doublets. The 77 K solution ESR spectrum (dimethylformamide, water–glycol 1∶1) for 2 is typical of a monomeric copper(II) centre and closely resembles the ESR spectrum of the type 2 site in Lc and AO. The ESR, electrospray mass spectrometric and NMR data indicate that 2 dissociates in solution to give a trinuclear unit consisting of two type 3 copper(II) centres (ESR silent), which are linked by the hydroxo and phosphate group (phosphate is released from the complex only on addition of acid), and an isolated type 2 copper(II) centre which is probably responsible for the ESR features.

First assignment of the rotational spectrum of a molecule containing two iodine nuclei: Spectroscopic constants and structure of CH2I2

The rotational spectrum of methylene iodide was assigned by combining information from broadband mm wave spectra of low-J transitions recorded with a supersonic-jet spectrometer and of high-J transitions measured for a room temperature sample. In the first step, the analysis of central frequencies of hyperfine multiplets for rotational transitions with J″ up to 189 resulted in constants of the rotational Hamiltonian HR, in which the fitted quartic centrifugal distortion constants were consistent with predictions made from ab initio calculations. The knowledge of HR allowed accurate prediction and assignment of the hyperfine structure due to the two iodine nuclei, which was made on the basis of well isolated splitting patterns observed in the jet and the effects of nuclear spin statistics visible therein. The final rotational constants are A=22 034.437(2), B=620.584(2), C=605.798(2) MHz and the hyperfine coupling constants are χaa=−1180.9(1), χbb−χcc=−892.42(5), |χab|=1358.9(5) MHz, and χzz=−2030.1(5), χxx=993.4(10), χyy=1036.7(1) MHz. The angle θza between the inertial a axis and the principal quadrupole axis z is 32.00(1)° and is consistent with ∠(CI⋅a)=33.0(2)° from the fitted structure. The structural parameters of the halogen in CH2I2 are r(CI)=2.134(2)Å and ∠(ICI)=114.0(3)° and compare well with extrapolation from the remaining methylene halides.

The 14N Nuclear Quadrupole Coupling in E- and Z-C-Cyanomethanimine; its Prediction from Restricted Hartree-Fock Wave Functions and its Experimental Determination by High Resolution Microwave Spectroscopy

Abstract The 14N hyperfine multiplets of low-7 rotational transitions of the E and Z isomers of HN = CH - C ≡ N, produced by flash pyrolysis from (CH3)2N -C ≡ N as precursor, were observed and analysed. The quadrupole coupling constants determined are (c-axis perpendicular to the molecular plane): The observed hfs multiplets were predicted with reasonable accuracy from RHF/6-311G** field gradients, once the latter had been scaled appropriately to compensate partly for the typical errors in the RHF-wave functions. The hitherto unmeasured 14N hyperfine multiplets of the related pyruvonitriles, H - N = C(CH3) - C ≡ N, are predicted.

Neutral currents in atomic and nuclear physics

The spin structure function of the proton measured by the EMC collaboration suggests an axial isoscalar neutral current for the nucleon. I study its implications for neutral current phenomena in atomic and nuclear physics. This includes parity-violating observables for transitions between hyperfine multiplets in light muonic atoms, selected inelastic neutrino nuclear reactions and the polarization asymmetry in electron scattering for isoscalar transitions. The neutrino-induced process 7Li → 7Li ∗(0.478 MeV) is particularly favourable for neutrino reactor experiments. I find that the axial isoscalar coupling extracted from the EMC measurement increases the neutrino cross section by 60%.