Imaging Recoil Ions from Optical Collisions between Ultracold, Metastable Neon Isotopes.

We present an experimental scheme that combines the well-established method of velocity-map imaging with a cold trapped metastable neon target. The device is used for obtaining the branching ratios and recoil-ion energy distributions for the penning ionization process in optical collisions of ultracold metastable neon. The potential depth of the highly excited dimer potential is extracted and compared with theoretical calculations. The simplicity to construct, characterize, and apply such a device makes it a unique tool for the low-energy nuclear physics community, enabling opportunities for precision measurements in nuclear decays of cold, trapped, short-lived radioactive isotopes.

Autoresonance Cooling of Ions in an Electrostatic Ion Beam Trap.

Autoresonance (AR) cooling of a bunch of ions oscillating inside an electrostatic ion beam trap is demonstrated for the first time. The relatively wide initial longitudinal velocity distribution is reduced by at least an order of magnitude using AR acceleration and ramping forces. The hot ions escaping the bunch are not lost from the system but continue to oscillate in the trap outside of the bunch and may be further cooled by successive AR processes. Ion-ion collisions inside the bunch close to the turning points in the trap's mirrors contribute to the thermalization of the ions. This cooling method can be applied to any mass and any charge.

SF6(-) photodetachment near the adiabatic limit.

High sensitivity photodetachment cross-section measurements of SF6(-) are performed near the adiabatic threshold limit. The extraction of adiabatic detachment energy (ADE) from the high sensitivity measurement of the cross-section change as a function of photon energy is discussed. Below the vertical detachment energy a steep 4 orders of magnitude cross-section drop is observed, with cross sections as low as 2 × 10(-6) Å(2) measured for photon energies below 2 eV. The cross-section is fitted with both the expected spectral shape based on recently calculated Frank-Condon overlaps and a phenomenological threshold function. The resulting 1.7 ± 0.02 eV ADE values are significantly higher than previously recommended experimental ADE values obtained based on kinetics modeling, and possible differences between the experimental approaches are discussed.

Cognition-immune interactions between executive function and working memory, tumour necrosis factor-alpha (TNF-alpha) and soluble TNF receptors (sTNFR1 and sTNFR2) in bipolar disorder.

OBJECTIVES: This study examined cognition-immune interactions, specifically executive function, working memory, peripheral levels of tumour necrosis factor-alpha (TNF-α), and soluble tumour necrosis factor receptors-1 and -2 (sTNFR1 and 2) levels in bipolar disorder (BD) patients in comparison with controls. METHODS: Thirty-one BD participants and twenty-seven controls participated in the study. The neurocognitive assessment was performed through three of CogState Research BatteryTM tasks for executive function and working memory. Plasma levels of TNF-α, sTNFR1, and sTNFR2 were measured after overnight fasting. Sociodemographic data and symptom severity of depression and mania were assessed. RESULTS: BD presented a significantly worse performance in the working memory task (p = .005) and higher levels of TNF-α (p = .043) in comparison to controls. A trend level of significance was found for sTNFR1 between groups (p = .082). Among BD participants, there were significant correlations between sTNFR2 and neurocognitive tasks (Groton Maze Learning Task: ρ = .54, p = .002; Set-Shifting Task: ρ = .37, p = .042; and the Two-Back Task: ρ = -.49, p = .005), and between sTNFR1 and mania, depression and anxiety symptoms (respectively ρ = .37, p = .038; ρ = -.38, p = .037; and ρ = .42, p = .002). CONCLUSION: TNF-α and its receptors might be an important variable in cognitive impairment in BD. Future studies might focus on the development of anti-inflammatory therapeutic targets for cognitive dysfunction in BD.

Structure and stability of the negative hydrogen molecular ion.

We present the results of a Coulomb explosion experiment that allows for the imaging of the rovibrational wave function of the metastable H2- ion. Our measurements confirm the predicted large internuclear separation of 6 a.u., and they show that the ion decays by autodetachment rather than by spontaneous dissociation. Imaging of the resulting H2 products reveals a large angular momentum of J = 25 ± 2, quantifying the rotation that leads to the metastability of this most fundamental molecular anion.

Fragmentation pathways of H+(H2O)2 after extreme ultraviolet photoionization.

Photofragmentation of the protonated water dimer H+(H2O)_{2}, a fundamental system both in aqueous solutions and gas-phase water clusters, has been studied at 13.8 nm using the Free Electron Laser FLASH in Hamburg. In a crossed-beam experiment using time-resolved, single-molecule fragment imaging, the two-body breakup into H2O++H3O+ was found as a prominent fragmentation channel with a kinetic energy release of up to 10 eV. This channel was observed with at least a similar yield as events with stronger fragmentation, producing protons together with neutral fragments and showing an absolute cross section of (0.5 ± 0.2) × 10(-18) cm2.

Hot water molecules from dissociative recombination of D3O+ with cold electrons.

Individual product channels in the dissociative recombination of deuterated hydronium ions and cold electrons are studied in an ion storage ring by velocity imaging using spatial and mass-sensitive detection of the neutral reaction fragments. Initial and final molecular excitation are analyzed, finding the outgoing water molecules to carry internal excitation of more than 3 eV in 90% of the recombination events. Initial rotation is found to be substantial and in three-body breakup strongly asymmetric energy repartition among the deuterium products is enhanced for hot parent ions.

N-acetylcysteine as an adjunctive treatment for smoking cessation: a randomized clinical trial.

OBJECTIVE: This randomized controlled trial examined the efficacy and safety of N-acetylcysteine as an adjunctive treatment for smoking cessation. METHODS: Heavy smokers were recruited from smoking cessation treatment for this 12- week randomized controlled trial. Eligible tobacco use disorder outpatients (n=34) were randomized to N-acetylcysteine or placebo plus first-line treatment. Abstinence was verified by exhaled carbon monoxide (COexh). The assessment scales included the Fagerström Test for Nicotine Dependence, the Hamilton Depression Rating Scale, the Hamilton Anxiety Rating Scale, the Minnesota Nicotine Withdrawal Scale, and the Medication Adherence Rating Scale. We also assessed anthropometrics, blood pressure, lipid profile, and soluble tumor necrosis factor receptor (sTNF-R) levels 1 and 2. RESULTS: First-line treatment for smoking cessation plus adjunctive N-acetylcysteine or placebo significantly reduced COexh (p < 0.01). In the N-acetylcysteine group, no significant changes were found in nicotine withdrawal symptoms, depressive and anxiety symptoms, anthropometric measures, blood pressure, or glucose compared to placebo. However, there was a significant reduction in sTNF-R2 levels between baseline and week 12 in the N-acetylcysteine group. CONCLUSIONS: These findings highlight the need to associate N-acetylcysteine with first-line treatment for smoking cessation, since combined treatment may affect inflammation and metabolism components. CLINICAL TRIAL REGISTRATION: NCT02420418.

Electron photodetachment cross sections of small carbon clusters: evidence for nonlinear isomers.

Absolute cross sections for photodetachment of negative carbon clusters are reported for Cn (n = 3, ..., 8). The results indicate that various neutral isomers exist, some with electron affinities as low as 1 electron volt. The method of production plays an important role in the characteristics of carbon clusters.

Ultraslow isomerization in photoexcited gas-phase carbon cluster [Formula: see text].

Isomerization and carbon chemistry in the gas phase are key processes in many scientific studies. Here we report on the isomerization process from linear [Formula: see text] to its monocyclic isomer. [Formula: see text] ions were trapped in an electrostatic ion beam trap and then excited with a laser pulse of precise energy. The neutral products formed upon photoexcitation were measured as a function of time after the laser pulse. It was found using a statistical model that, although the system is excited above its isomerization barrier energy, the actual isomerization from linear to monocyclic conformation takes place on a very long time scale of up to hundreds of microseconds. This finding may indicate a general phenomenon that can affect the interstellar medium chemistry of large molecule formation as well as other gas phase processes.

An experimental setup to study delayed electron emission upon photoexcitation of trapped polyatomic anions.

A Velocity Map Imaging (VMI) spectrometer has been designed and integrated with an electrostatic ion beam trap to study delayed electron emission from trapped polyatomic anions upon photodetachment. The VMI spectrometer is small in size and can record a wide range of photoelectron energies, with variable magnification. Delayed electron emission can be recorded in our experimental setup for any time duration after the photoexcitation of the polyatomic anions. Experiments were carried out with trapped O- and C5- ions to demonstrate the capability of the spectrometer. Delayed electron emissions from C5- as well as prompt photoelectrons from O- were detected by the VMI spectrometer upon photoexcitation. The design and performance of the spectrometer are presented in detail.

Observation of longitudinal quadrupole ion bunch oscillations in an electrostatic ion beam trap.

Ions in an ion bunch trapped inside an Electrostatic Ion Beam Trap (EIBT) exhibit collective oscillations within the bunch under the influence of an external driving force. These internal oscillations have been measured explicitly using a new method with a particle detector outside the EIBT. In this approach, the evolving ion bunch is monitored along the entire trap length, in contrast to the localized single point measurements that are often carried out in other techniques. In the present study, quadrupole oscillations have been measured for the first time in an EIBT along with the dipole oscillations that were measured previously. The frequency of the quadrupole oscillation is found to be about twice the dipole oscillation frequency. This is in agreement with the prediction of a theoretical model.

The cryogenic storage ring CSR.

An electrostatic cryogenic storage ring, CSR, for beams of anions and cations with up to 300 keV kinetic energy per unit charge has been designed, constructed, and put into operation. With a circumference of 35 m, the ion-beam vacuum chambers and all beam optics are in a cryostat and cooled by a closed-cycle liquid helium system. At temperatures as low as (5.5 ± 1) K inside the ring, storage time constants of several minutes up to almost an hour were observed for atomic and molecular, anion and cation beams at an energy of 60 keV. The ion-beam intensity, energy-dependent closed-orbit shifts (dispersion), and the focusing properties of the machine were studied by a system of capacitive pickups. The Schottky-noise spectrum of the stored ions revealed a broadening of the momentum distribution on a time scale of 1000 s. Photodetachment of stored anions was used in the beam lifetime measurements. The detachment rate by anion collisions with residual-gas molecules was found to be extremely low. A residual-gas density below 140 cm(-3) is derived, equivalent to a room-temperature pressure below 10(-14) mbar. Fast atomic, molecular, and cluster ion beams stored for long periods of time in a cryogenic environment will allow experiments on collision- and radiation-induced fragmentation processes of ions in known internal quantum states with merged and crossed photon and particle beams.

N-acetylcysteine as an adjunctive treatment for smoking cessation: a randomized clinical trial

Objective: This randomized controlled trial examined the efficacy and safety of N-acetylcysteine as an adjunctive treatment for smoking cessation. Methods: Heavy smokers were recruited from smoking cessation treatment for this 12- week randomized controlled trial. Eligible tobacco use disorder outpatients (n=34) were randomized to N-acetylcysteine or placebo plus first-line treatment. Abstinence was verified by exhaled carbon monoxide (COexh). The assessment scales included the Fagerström Test for Nicotine Dependence, the Hamilton Depression Rating Scale, the Hamilton Anxiety Rating Scale, the Minnesota Nicotine Withdrawal Scale, and the Medication Adherence Rating Scale. We also assessed anthropometrics, blood pressure, lipid profile, and soluble tumor necrosis factor receptor (sTNF-R) levels 1 and 2. Results: First-line treatment for smoking cessation plus adjunctive N-acetylcysteine or placebo significantly reduced COexh (p < 0.01). In the N-acetylcysteine group, no significant changes were found in nicotine withdrawal symptoms, depressive and anxiety symptoms, anthropometric measures, blood pressure, or glucose compared to placebo. However, there was a significant reduction in sTNF-R2 levels between baseline and week 12 in the N-acetylcysteine group. Conclusions: These findings highlight the need to associate N-acetylcysteine with first-line treatment for smoking cessation, since combined treatment may affect inflammation and metabolism components. Clinical trial registration: NCT02420418

Fourier transform time-of-flight mass spectrometry in an electrostatic ion beam trap

We report on the application of an electrostatic ion beam trap as a mass spectrometer. The instrument is analogous to an optical resonator; ions are trapped between focusing mirrors. The storage time is limited by the residual gas pressure and reaches up to several seconds, resulting in long ion flight paths. The oscillation of ion bunches between the mirrors is monitored by nondestructive image charge detection in a field-free region and mass spectra are obtained via Fourier transform. The principle of operation is demonstrated by measuring the mass spectrum of trapped Ar+ and Xe+ particles, produced by a standard electron impact ion source. Also, mass spectra of heavier PEGnNa+ and bradykinin ions from a pulsed MALDI ion source were obtained. The long ion flight path, combined with mass-independent charge detection, makes this system particularly interesting for the investigation of large molecules.

Absolute photo-destruction and photo-fragmentation cross section measurements using an electrostatic ion beam trap.

We describe a technique to measure absolute photo-induced cross sections for cluster anions stored in an electrostatic ion beam trap (EIBT) with a central deflector. The setup allows determination of total photo-destruction cross sections as well as partial cross sections for fragmentation and electron detachment. The unique properties of this special EIBT setup are investigated and illustrated using small Al(n)(-) clusters.

A cryogenic electrostatic trap for long-time storage of keV ion beams.

We report on the realization and operation of a fast ion beam trap of the linear electrostatic type employing liquid helium cooling to reach extremely low blackbody radiation temperature and residual gas density and, hence, long storage times of more than 5 min which are unprecedented for keV ion beams. Inside a beam pipe that can be cooled to temperatures <15 K, with 1.8 K reached in some locations, an ion beam pulse can be stored at kinetic energies of 2-20 keV between two electrostatic mirrors. Along with an overview of the cryogenic trap design, we present a measurement of the residual gas density inside the trap resulting in only 2 x 10(3) cm(-3), which for a room temperature environment corresponds to a pressure in the 10(-14) mbar range. The device, called the cryogenic trap for fast ion beams, is now being used to investigate molecules and clusters at low temperatures, but has also served as a design prototype for the cryogenic heavy-ion storage ring currently under construction at the Max-Planck Institute for Nuclear Physics.