lapushkin@ms.ioffe.ru Abstract. The electron-stimulated desorption of lithium and potassium atoms from LixAuy and KAu layers on the surface of gold adsorbed on W(100) has been studied. The yield of x y electron-stimulated desorption of Li and K atoms was measured by a direct method as a func-tion of the electron energy, the concentration of Li and K atoms, and the thickness of the Au film. The formation of semiconductor intermetallic compounds LixAuy and KxAuy is considered.

Precise determination of the isotope masses of superheavy elements obtained by the complete fusion of 48 Ca + ions with Au, Pb, Bi, U, and Pu targets can provide valuable information on the mechanisms of nuclear reactions leading to the formation of these elements. A specialized multi-turn time-of-flight mass spectrometer is to be used to match the goal. The source of the target isotopes is a DC-280 cyclotron, a «factory of superheavy elements» at the Joint Institute for Nuclear Research (JINR, Dubna, Russia). The point of the problem is that ions of superheavy elements are formed quite rarely even in the specialized accelerator of JINR: during the last experiment, the frequency of their appearance was up to 10 events per day. Precise determination of the mass number requires comparing the time of flight of a superheavy ion through a mass analyzer with the same time for a calibrant ion, the mass number and charge of which are precisely known a priori from the process of its formation. Implementation of such a mass spectrometric analysis required the development of an ion source capable of stable operation for a long time. To solve the problem, a number of ion sources were considered. The choice of an ion source with electron ionization is substantiated. A source with a crucible in which the calibrant evaporates during heating was proposed and tested. Various substances (PbBr 2 , Nd, C60, fullerene soot) were considered as a calibrant. The mass spectra of these compounds are presented, namely, the spectrum of neodymium compounds and the mass spectrum of fullerene soot. It is shown that the use of fullerene soot is optimal, since the mass spectrum of fullerene soot contains ions in the range of mass numbers from 12 to 800 and higher. Moreover, the mass spectrum of fullerene soot contains many peaks in the mass number region of interest 275 – 300 a.m.u. It has been experimentally shown that the ion intensities within the indicated range differ by less than an order of magnitude which makes the use of fullerene soot a standard sample for calibration of a high-resolution time-of-flight mass spectrometer.

The present work is devoted to the study of the possibility of electrospray onto the surface of a liquid in order to accumulate the products of reactions occurring in micro- and nanodroplets of the electrospray torch. The experimental device was made for research purposes. A stable mode of electrospray of a water-ethanol mixture (1:4) onto a liquid electrode (water-ethanol mixture (1:4)), without using sputting gas, was obtained at a spray voltage U of at least 4 kV and a distance between the spray needle and the surface of the liquid R of no more than 15 mm. The spray current increased as the distance between the spray needle and the surface of the liquid electrode decreased and the spray voltage increased. A stable mode of electrospray of the reaction mixture (4 ml of a mixture of acetonitrile and 0.2 % formic acid solution in water (1: 1), 0.5 ml of aniline and 0.5 ml of acetone) onto the surface of the liquid electrode (mixture of 6 ml of acetonitrile and 6 ml of 0.2 % formic acid solution in water or a mixture of 6 ml of acetonitrile and 6 ml of water) with the use of the sputting gas was obtained with the following values of the parameters of the experimental device: the flow rate of the spray solution Qp = = 100 μL / min, the spray voltage U = 3.2 kV, the distance between the surface of the liquid electrode and the spray needle R = 35 mm. The maximum flow rate of the sputting gas was 2 L/min. Unreacted substances and the chemical reactions products of the components of the sprayed reaction mixture accumulated in the liquid electrode when the given values of the parameters of the device were used. This was confirmed by spectrophotometric measurements.

О МЕХАНИЗМЕ ФОРМИРОВАНИЯ КАПЕЛЬ В Х-ОБРАЗНОМ МИКРОФЛЮИДНОМ УСТРОЙСТВЕВ работе описаны результаты экспериментального исследования генерирования микроэмульсий в микрофлюидном устройстве собственного производства, оснащенном X-образным смесителем.Представленные карты режимов показали значительное влияние концентрации поверхностно-активных веществ на режим течения в канале и на размер формируемых капель.Получено универсальное уравнение для расчета критических капиллярных чисел, определяющих переход между режимами течения

AbstractThe transport of charged particles generated during electrospray in a longitudinal gasdynamic field has been studied in a model system comprising two coaxial electrodes and a collector grid. The process has been numerically simulated with omission of the role of a space charge. A comparison of the results shows that the space charge is a key factor determining the transport of charged particles: the model transport efficiency in the absence of space charge reaches 80–100%. In experiment, the efficiency strongly depends on the space charge and amounts to 70–80% for its minimum values, while decreasing to 20–30% with increasing electrospray current.

The transport of charged particles generated during electrospray in a longitudinal gasdynamic field has been studied in a model system comprising two coaxial electrodes and a collector grid. The process has been numerically simulated with omission of the role of a space charge. A comparison of the results shows that the space charge is a key factor determining the transport of charged particles: the model transport efficiency in the absence of space charge reaches 80–100%. In experiment, the efficiency strongly depends on the space charge and amounts to 70–80% for its minimum values, while decreasing to 20–30% with increasing electrospray current.

Проведено экспериментальное изучение распределения тока электрораспыления, генерируемого в системе с двумя противоэлектродами. Показано, что при малых значениях общего тока его распределение между электродами пропорционально потоку электрического поля, приходящегося на данный электрод. С ростом тока электрораспыления эта пропорциональность нарушается в направлении более равномерного распределения, видимо, вследствие роста роли объемного заряда, расталкивающего заряженные частицы. DOI: 10.21883/PJTF.2017.10.44624.16641

We have experimentally studied the distribution of current in an electrospray system with two counter-electrodes. It is established that, at low values of the total current, its distribution between these electrodes is proportional to the electric field flux to a given electrode. As the total current grows, this proportionality changes toward more uniform distribution, probably, due to increased role of a space charge producing mutual repulsion of charged particles.