Search results for "PLASMA"
showing 10 items of 4043 documents
Narrow-band pulsed electron source based on near-threshold photoionization of Cs in a magneto-optical trap
2019
The newly developed method of time-of-flight (ToF) momentum microscopy was used to analyse the cold electron emission from a Cs 3D magneto-optical trap (MOT). Three-step resonant photoionization was implemented via two intermediate states (6P3/2 pumped with 852 nm laser and 7S1/2 with 1470 nm) and a tuneable femtosecond Ti:sapphire laser for the final ionization step. The magnetic field of the MOT is switched off during the photoionization step. The natural bandwidth of the fs-laser is reduced to 4 meV using optical spectral filters. Precise tuning of the photon energy makes it possible to observe the transition regime between direct photoemission into the open continuum and field induced i…
Measurement of untruncated nuclear spin interactions via zero- to ultralow-field nuclear magnetic resonance
2015
Zero- to ultra-low-field nuclear magnetic resonance (ZULF NMR) provides a new regime for the measurement of nuclear spin-spin interactions free from effects of large magnetic fields, such as truncation of terms that do not commute with the Zeeman Hamiltonian. One such interaction, the magnetic dipole-dipole coupling, is a valuable source of spatial information in NMR, though many terms are unobservable in high-field NMR, and the coupling averages to zero under isotropic molecular tumbling. Under partial alignment, this information is retained in the form of so-called residual dipolar couplings. We report zero- to ultra-low-field NMR measurements of residual dipolar couplings in acetonitrile…
Sawtooth-wave adiabatic-passage slowing of dysprosium
2018
We report on sawtooth wave adiabatic passage (SWAP) slowing of bosonic and fermionic dysprosium isotopes by using a 136 kHz wide transition at 626 nm. A beam of precooled atoms is further decelerated in one dimension by the SWAP force and the amount of atoms at near zero velocity is measured. We demonstrate that the SWAP slowing can be twice as fast as in a conventional optical molasses operated on the same transition. In addition, we investigate the parameter range for which the SWAP force is efficiently usable in our set-up, and relate the results to the adiabaticity condition. Furthermore, we add losses to the hyperfine ground-state population of fermionic dysprosium during deceleration …
Observation of a narrow inner-shell orbital transition in atomic erbium at 1299 nm
2021
We report on the observation and coherent excitation of atoms on the narrow inner-shell orbital transition, connecting the erbium ground state $[\mathrm{Xe}] 4f^{12} (^3\text{H}_6)6s^{2}$ to the excited state $[\mathrm{Xe}] 4f^{11}(^4\text{I}_{15/2})^05d (^5\text{D}_{3/2}) 6s^{2} (15/2,3/2)^0_7$. This transition corresponds to a wavelength of 1299 nm and is optically closed. We perform high-resolution spectroscopy to extract the $g_J$-factor of the $1299$-nm state and to determine the frequency shift for four bosonic isotopes. We further demonstrate coherent control of the atomic state and extract a lifetime of 178(19) ms which corresponds to a linewidth of 0.9(1) Hz. The experimental findi…
Anisotropic light-shift and magic-polarization of the intercombination line of Dysprosium atoms in a far-detuned dipole trap
2018
We characterize the anisotropic differential ac-Stark shift for the Dy $626$ nm intercombination transition, induced in a far-detuned $1070$ nm optical dipole trap, and observe the existence of a "magic polarization" for which the polarizabilities of the ground and excited states are equal. From our measurements we extract both the scalar and tensorial components of the dynamic dipole polarizability for the excited state, $\alpha_E^\text{s} = 188 (12)\,\alpha_\text{0}$ and $\alpha_E^\text{t} = 34 (12)\,\alpha_\text{0}$, respectively, where $\alpha_\text{0}$ is the atomic unit for the electric polarizability. We also provide a theoretical model allowing us to predict the excited state polari…
Coherence and entanglement dynamics of vibrating qubits
2017
We investigate the dynamics of coherence and entanglement of vibrating qubits. Firstly, we consider a single trapped ion qubit inside a perfect cavity and successively we use it to construct a bipartite system made of two of such subsystems, taken identical and noninteracting. As a general result, we find that qubit vibration can lead to prolonging initial coherence in both single-qubit and two-qubit system. However, despite of this coherence preservation, we show that the decay of the entanglement between the two qubits is sped up by the vibrational motion of the qubits. Furthermore, we highlight how the dynamics of photon-phonon correlations between cavity mode and vibrational mode, which…
Unconventional phases of attractive Fermi gases in synthetic Hall ribbons
2017
An innovative way to produce quantum Hall ribbons in a cold atomic system is to use M hyperfine states of atoms in a one-dimensional optical lattice to mimic an additional "synthetic dimension." A notable aspect here is that the SU(M) symmetric interaction between atoms manifests as "infinite ranged" along the synthetic dimension. We study the many-body physics of fermions with SU(M) symmetric attractive interactions in this system using a combination of analytical field theoretic and numerical density-matrix renormalization-group methods. We uncover the rich ground-state phase diagram of the system, including unconventional phases such as squished baryon fluids, shedding light on many-body…
Valutazione e caratterizzazione bio-agronomica e qualitativa di popolazioni di avena (Avena sativa L.) di origine siciliana.
2013
Tra i cereali minori l’avena ((Avena sativa L.) costituisce una importante risorsa agronomica e economica per gli areali mediterranei. Infatti, questa specie è caratterizzata da una maggiore rusticità rispetto a cereali maggiori come il grano duro, che le permettono di ben adattarsi ad ambienti di coltivazione collinari marginali delle aree meridionali. L’ampia gamma di destinazione produttiva della specie sia per l’alimentazione umana (granella) che animale (foraggio-granella, pascolo-fieno, pascolo-insilato) la rendono una specie assai interessante per le aziende cerealicolo-zootecniche. Inoltre, tale specie, ha già promosso una interessante attività sia nel settore agro-alimentare e sia …
The Low-Affinity ATP Binding Site of the Escherichia coli SecA Dimer Is Localized at the Subunit Interface
1997
The homodimeric SecA protein is the ATP-dependent force generator in the Escherichia coli precursor protein translocation cascade. SecA contains two essential nucleotide binding sites (NBSs), i.e., NBS1 and NBS2 that hind ATP with high and low affinity, respectively. The photoactivatable bifunctional cross-linking agent 3'-arylazido-8-azidoadenosine 5'-triphosphate (diN(3)ATP) was used to investigate the spatial arrangement of the nucleotide binding sites of SecA, DiN(3)ATP is an authentic ATP analogue as it supports SecA-dependent precursor protein translocation and translocation ATPase, UV-induced photo-cross-linking of the diN(3)ATP-bound SecA results in the formation of stable dimeric s…
Metabolomics of Human Amniotic Fluid and Maternal Plasma during Normal Pregnancy
2016
Metabolic profiles of amniotic fluid and maternal blood are sources of valuable information about fetus development and can be potentially useful in diagnosis of pregnancy disorders. In this study, we applied 1H NMR-based metabolic profiling to track metabolic changes occurring in amniotic fluid (AF) and plasma (PL) of healthy mothers over the course of pregnancy. AF and PL samples were collected in the 2nd (T2) and 3rd (T3) trimester, prolonged pregnancy (PP) until time of delivery (TD). A multivariate data analysis of both biofluids reviled a metabolic switch-like transition between 2nd and 3rd trimester, which was followed by metabolic stabilization throughout the rest of pregnancy proba…