Multistage Zeeman deceleration of metastable neon

A supersonic beam of metastable neon atoms has been decelerated by exploiting the interaction between the magnetic moment of the atoms and time-dependent inhomogeneous magnetic fields in a multistage Zeeman decelerator. Using 91 deceleration solenoids, the atoms were decelerated from an initial velocity of 580 m/s to final velocities as low as 105 m/s, corresponding to a removal of more than 95% of their initial kinetic energy. The phase-space distribution of the cold, decelerated atoms was characterized by time-of-flight and imaging measurements, from which a temperature of 10 mK was obtained in the moving frame of the decelerated sample. In combination with particle-trajectory simulations, these measurements allowed the phase-space acceptance of the decelerator to be quantified. The degree of isotope separation that can be achieved by multistage Zeeman deceleration was also studied by performing experiments with pulse sequences generated for (20)Ne and (22)Ne.     

Stopping paramagnetic supersonic beams: the advantage of a co-moving magnetic trap decelerator

The long standing goal of chemical physics is finding a convenient method to create slow and cold beams intense enough to observe chemical reactions in the temperature range of a few Kelvin. We present an extensive numerical analysis of our moving magnetic trap decelerator showing that a 3D confinement throughout the deceleration process enables deceleration of almost all paramagnetic particles within the original supersonic expansion to stopping velocities. We show that the phase space region containing the decelerating species is larger by two orders of magnitude as compared to other available deceleration methods.     

Producing translationally cold, ground-state CO molecules

Carbon monoxide molecules in their electronic, vibrational, and rotational ground state are highly attractive for trapping experiments. The optical or ac electric traps that can be envisioned for these molecules will be very shallow, however, with depths in the sub-milliKelvin range. Here, we outline that the required samples of translationally cold CO (X(1)Σ(+), v' = 0, N' = 0) molecules can be produced after Stark deceleration of a beam of laser-prepared metastable CO (a(3)Π(1)) molecules followed by optical transfer of the metastable species to the ground state via perturbed levels in the A(1)Π state. The optical transfer scheme is experimentally demonstrated and the radiative lifetimes and the electric dipole moments of the intermediate levels are determined.     

Cold Molecules: Preparation,Applications, and Challenges

Research with cold molecules has developed rapidly in recent years. There is now a variety of established methods for cooling molecules into the millikelvin range. Nevertheless, a focal point of current research is directed toward finding new ways to bring the temperature of molecules even closer to absolute zero. Samples of cold molecules offer not only important applications for high‐resolution spectroscopy, which benefit from the increased interaction time of slow molecules with electromagnetic radiation; they also promise access to an exotic regime of chemical reactivity, in which phenomena such as quantum tunneling and quantum resonances predominate. This review begins with an introduction to the methods by which cold molecules can be prepared, with special emphasis on Stark deceleration and traps. In addition to applications of cold molecules that have already been partially achieved, an important focus of the review concentrates on possible future applications, and both aspects are illustrated with selected examples.     

The use of relative deceleration properties in the determination of chromium by PIPPS

Using particle induced prompt photon spectrometry, PIPPS, the ratios of deceleration values of charged particles in samples and standards can be used to determine elemental compositions. Through the spiking of samples and standards with a compound containing a known amount of a non-analyte element (lithium), to which a relative decelaration value is ascribed, appropriate relative deceleration values for samples and standards can be assessed by measuring the prompt -ray yields induced in the spike. Using 5 MeV protons this method was tested for the determination of chromium in a selection of reference standards using pure compounds of chromium as analyte standards. The application of both the average cross section as well as the average stopping power approaches were investigated.     

On the use of relative deceleration values for the determination of silicon by PIGE

By spiking the samples with a compound containing both a non-analyte and an analyte element, to which a relative deceleration property for 5 Me V protons has been ascribed, relative deceleration values for the samples could be obtained by measuring the prompt -yields induced in the non-analyte element. These values are used to correct for matrix effects in elemental analysis using PIGE techniques. In addition to this, the analytical results thus obtained can also be compared to those obtained by the simultaneous application of the analyte spiking technique to the collected yield data. These non-analyte spiking approaches were used to analyze silicon in polymer materials. These methods were tested by analyzing the two reference standards BCS 308 and Standard Chrome Ore XXXI. Li₂SiO₃, containing both the non-analyte as well as the analyte element, was selected as comparator and spike. Results obtained for the polymer samples were also compared to those obtained by PIXE.     

Cold heteromolecular dipolar collisions

Cold molecules promise to reveal a rich set of novel collision dynamics in the low-energy regime. By combining for the first time the techniques of Stark deceleration, magnetic trapping, and cryogenic buffer gas cooling, we present the first experimental observation of cold collisions between two different species of state-selected neutral polar molecules. This has enabled an absolute measurement of the total trap loss cross sections between OH and ND(3) at a mean collision energy of 3.6 cm(-1) (5 K). Due to the dipolar interaction, the total cross section increases upon application of an external polarizing electric field. Cross sections computed from ab initio potential energy surfaces are in agreement with the measured value at zero external electric field. The theory presented here represents the first such analysis of collisions between a (2)Π radical and a closed-shell polyatomic molecule.     

A supersonic beam of cold lithium hydride molecules

We have developed a source of cold LiH molecules for Stark deceleration and trapping experiments. Lithium metal is ablated from a solid target into a supersonically expanding carrier gas. The translational, rotational, and vibrational temperatures are 0.9+/-0.1, 5.9+/-0.5, and 468+/-17 K, respectively. Although they have not reached thermal equilibrium with the carrier gas, we estimate that 90% of the LiH molecules are in the ground state, X (1)Sigma(+)(v=0,J=0). With a single 7 ns ablation pulse, the number of molecules in the ground state is 4.5+/-1.8 x 10(7) molecules/sr. A second, delayed, ablation pulse produces another LiH beam in a different part of the same gas pulse, thereby almost doubling the signal. A long pulse, lasting 150 micros, can make the beam up to 15 times more intense.     

Thermal stability, texture, liquid holding capacity and colour of smoked salmon on retail level

Retail samples of vacuum-packed sliced cold smoked salmon were investigated for changes in texture, colour and expressible moisture approximately 1 week before expiry date and on the best before date. For comparison, retail samples of gravelax were also investigated. To gather information on alteration in protein caused by processing and refrigerated storage, DSC measurements were performed at the same samples and furthermore on hot smoked salmon and frozen raw material, Salmo salar. Texture parameters varied markedly between the retail samples; however, almost no clear tendencies were observable with increased refrigerated storage time while expressible moisture raised. Colour also differed considerably between the samples. Gravelax behaved almost comparable to cold smoked salmon. DSC curves taken from cold smoked salmon and gravelax were almost comparable and demonstrated that muscle proteins being largely denatured by the influence of salt and cold smoking temperature compared to the raw material.     

Deceleration of high-energy matrix-assisted laser desorption/ionization ions in an open cell for Fourier transform ion cyclotron resonance mass spectrometry.

A new method of ion deceleration in a Fourier transform ion cyclotron resonance (FTICR) open cell is described that improves the performance of FTICR-MS instruments equipped with an internal source for laser desorption/ionization. Ion deceleration occurs in the front trapping cylinder of an open cylindrical cell. Decelerating voltages up to 100 V can be applied for 10-500 micros to the front cylinder during ion introduction. The deceleration field is uniformly distributed along the cylinder length giving a "smooth" deceleration, which means that the deceleration is effective over a large time interval and a large m/z range. This results in improved trapping efficiency of high-energy ions. We demonstrate efficient trapping of high (m/z 66 kDa) mass ions and the possibility to reduce the width of the kinetic energy distribution of MALDI ions with this arrangement.     

Crystallization of oxidized isotactic polypropylene

The effect of processes accompanying thermal oxidation of the polymer on the characteristics of its isothermal crystallization has been revealed. It has been shown that crystallization decelerates with a rise in the degree of PP oxidation. The higher the concentration of functional groups, the stronger the deceleration. The energy of nucleation increases when passing from virgin to oxidized PP samples. The higher the concentration of carbonyl groups accumulated in polymer chains, the more pronounced this effect, although the degradation of the chains must lead to a reduction in this parameter. It has been concluded that the kinetic and thermodynamic parameters of the isothermal crystallization are applicable to investigation of processes accompanying thermal oxidation of the crystallizable polymer.     

Nickel hydroxide obtained by high-temperature two-step synthesis as an effective material for supercapacitor applications

Hybrid supercapacitors with nickel hydroxide electrode are widely used as modern power sources for electrovehicles, ignition of different electric engines, etc. Nickel hydroxide for supercapacitor use must satisfy special features which are quite different from those requested for battery application. The aim of this work is to improve the promising two-stage high-temperature method by altering hydrolysis condition (hot and cold) in order to obtain Ni(OH)₂ with improved electrochemical activity. Ni(OH)₂ samples have been investigated by PXRD, TG, DSC, SEM, TEM, cyclic voltammogramm, and galvanostatic charge-discharge cycling. It has been established from PXRD, TG, and DSC analyses that material obtained by hydrolysis at high temperature is a highly crystalline β-Ni(OH)₂ characterized by high thermal stability. Materials prepared by cold hydrolysis are a highly defective β_bc-Ni(OH)₂, with 6.3 % water content and a lower thermal stability. It has been shown that samples prepared by hot hydrolysis have a high redox reversibility and electrochemical cycling stability, but a lower electrochemical capacity. This suggests that the electrochemical processes are localized in the thin layer at the particle surface. Cyclic voltammograms of samples prepared by cold hydrolysis exhibit gradual activation of the active material, anyhow resulting in higher capacity. By means of the galvanostatic charge-discharge curves at different current densities, the specific capacities of the samples have been calculated. The sample prepared by cold hydrolysis has higher specific capacities than the sample prepared by hot hydrolysis.     

Multistage electrophoresis II: treatment of a kinetic separation as a pseudoequilibrium process

An electrophoresis device is described which separates cells, particles, proteins and other separands by collecting samples having decreasing electrophoretic mobility in a train of inverted cavities while an electric field is applied between the inverted cavities and a sample cuvette containing a mixture of cells, particles, proteins or other separands. A circular plate is provided for the inverted cavities, and this circular plate is rotated to collect fractions. The system utilizes an innovative purification method that combines free electrophoresis and multistage extraction in an instrument capable of separating living cells, particles, and proteins in useful quantities at high concentrations. Most multistage processes are based on equilibrium separations, but electrophoresis is a kinetic separation; therefore, a pseudoequilibrium paradigm was developed for use in optimizing separation parameters including number of stages and electrophoresis time per stage. This paradigm allows the application of McCabe-Thiele type analysis, and it was calculated, for example, that two separands differing by 20% in electrophoretic mobility can be purified to 95% purity with acceptable yield in about seven stages. Laboratory experiments demonstrated a 95% purification in four stages of a separand originally present at 4% when electrophoretic mobilities differed by 80%.     

Methanol transport in PMMA: The effect of mechanical deformation

The effect of cold work on the transport of liquid methanol in crosslinked PMMA disks has been determined at temperatures from 35–56°C. Deformed samples absorb at fast rates with kinetics that approach those of Fickian diffusion. Undeformed samples sorb at lower rates and the kinetics tend toward those of Case II transport. Shape recovery accompanied swelling in deformed samples. Samples saturated with methanol were desorbed in cyclohexanol. Resorption of desorbed samples showed fast rates for both deformed and undeformed samples and matched those of the absorption cycle in deformed samples. An analogy is made between the microstructure due to cold work and due to swelling.     

Hydrothermal synthesis and catalytic properties of superacid sulfated titania

The micromorphology and catalytic properties of nanocrystalline TiO₂/SO₄²⁻ superacid systems prepared by a conventional sol-gel process, as well as hydrothermal (HT) and microwave-hydrothermal (MW-HT) processes, were analyzed. The samples prepared by the HT process have no developed surfaces and, as a consequence, have no high reactivity in isobutylene oligomerization. The TiO₂/SO₄²⁻ samples prepared by single-step MW-HT synthesis in their morphologic, acid, and catalytic properties are competitive with the systems prepared by the conventional multistage sol-gel process.     

A new sampling format for the diagnostics of bovine infectious diseases in dried blood spots by ELISA

The detection of antibodies to bovine infectious diseases (enzootic bovine leucosis, viral diarrhea, and infectious rhinotracheitis) is performed by ELISA in dry whole blood samples obtained on porous membranes using a new sampling format. Several commercial test systems are used to diagnose the infections. The obtained data are compared to the results of the analysis of liquid samples of blood serum. The results of the analysis of dried and liquid samples are in full concordance. The new sampling format makes it possible to avoid using a cold chain for the transportation of samples to diagnostic laboratories and to simplify the storage of these samples.     

Use of a Split Microtron for Instrumental Gamma Activation Analysis

The potentials of a split microtron with an electron beam energy of up to 70 MeV for the gamma activation analysis of some natural samples were studied. Certified reference materials of bottom sediments—terrigenous clay (SDO-1), volcanic-terrigenous mud (SDO-2), and lime mud (SDO-3)—were used as model samples. The samples were irradiated with photons generated upon the deceleration of an electronic beam with an energy of 20–50 MeV. The beam was controlled by placing a gold foil before the test sample. Activation products of C, Cl, Na, Mg, Ti, Fe, Ca, Zr, Mn, Rb, Sr, Ni, Co, Y, As, Ba, Zn, Cs, Sc, Cr, and Ce were identified by gamma lines using a high-purity germanium detector.     

X-ray scattering and thermal analysis study of the effects of molecular weight on phase structure in blends of poly(butylene terephthalate) with polycarbonate

Blends of Poly(butylene terephthalate), PBT, with Polycarbonate, PC, were studied for a range of molecular weights and blend compositions. Blends were available in PBT/PC compositions 80/20 and 40/60, and with M_w designated by H (high) or L (low). Samples were prepared by melt crystallization, or by cold crystallization following a rapid quench from the melt. Addition of PC reduces the crystallization kinetics of PBT so that the resulting crystals are more perfect than those which form in the homopolymer. Degree of crystallinity of the blends followed the rank ordering: L/L > L/H > H/L = H/H. The glass transition behavior was investigated using dynamic mechanical analysis (DMA) and modulated differential scanning calorimetry (MDSC). All blends exhibited two glass transitions at intermediate temperatures between the T_gs of the homopolymers, indicating existence of a PBT-rich phase and a PC-rich phase. Blends L/L were most, and H/H the least, miscible. Small-angle X-ray scattering was performed at room temperature on cold crystallized blends, or at elevated temperature during melt crystallization. The long period was consistently larger, and the linear stack crystallinity was consistently smaller, in blends L/L or H/L. These results indicate that in blends containing low M_w PC, there is more PC located within the PBT-rich phase. The long period was consistently smaller in cold crystallized samples, while the linear stack crystallinity was nearly the same, regardless of melt or cold crystallization treatment. Reduction of the average long period in cold crystallized samples could result from crystallization of PBT within the PC-rich phase. This is consistent with thermal analysis results, which indicate that cold crystallized samples have greater overall crystallinity than melt crystallized samples. A hypothetical liquid phase diagram is presented to explain the differences between melt and cold crystallized blends. © 1996 John Wiley & Sons, Inc.     

Cold ultrasonic acid extraction of copper, lead and zinc from soil samples

A cold ultrasonic acid method for extracting Pb, Cu and Zn from soil samples has been studied. This work focused on studying the experimental condition for extrating trace metals from soil samples at ambient temperature (≈25 °C) using Syrian soil samples; the same conditions were applied to reference soil samples(SL-1, Soil-7, SDM, and BCR-32). A short exposure time (4 h), and 2 ml of concentrated hydrochloric acid were found to be best. Under the applied conditions Pb, Cu and Zn were quantitavely extracted, while Sr, Mn, Fe, Al, Cr, Co, and Ni were partialy extracted. The advantages of the cold ultrasonic extraction method are as follows: it is selective, it is matrix free, the extraction time is short, the amounts of consumed chemicals are small, the by-products of the process are negligible and it is environmentally clean, since no fume emissions are emitted. The only disadvantage is that it is not a real total digestion method. Comparable results for the proposed ultrasound method and the hot-plate acid digestion method for Cu, Pb and Zn in certified refrence soil samples(SL-1, SDM, Soil-7, BCR-32, Soil-6) and some Syrian soil samples are obtained.     

Investigation of the separation efficiency in one-stage and multistage extractions by a numerical method

Theoretical separation efficiencies in one-stage static and multistage dynamic models of liquid-liquid extraction have been studied mathematically. By the use of the iterative numerical method the maximum difference between separation efficiencies in these two models, as well as the absolute values of the respective separation efficiencies were calculated at this maximum. The maximum difference between multistage and one-stage separation efficiencies amounts to 20.36%, when the respective separation efficiencies are about 91.89% and 71.56%.