Cluster-assisted generation of multicharged ions in nanosecond laser ionization of carbon bisulfide clusters at 1064nm

The photoionization of seeded carbon bisulfide molecular beam by a 1064nm nanosecond Nd-YAG laser with intensities varying from 0.8 × 10^11 to 5.6 × 10^11 W/cm^2 have been studied by time-of-flight mass spectrometry. Multiply charged ions of S^q＋ （q = 2 6） and C^q＋ （q = 2-4） with kinetic energy of hundreds of electron volts have been observed, and there are strong experimental evidences indicating that those multicharged ions originate from the ionization of CS2 neat clusters in the beam. An electron reeolliding ionization model is proposed to explain the appearance of those multiply charged atomic ions under such low laser intensities.

Formation of Multicharged Metal Ions in Vacuum Arc Plasma Heated by Gyrotron Radiation

A new method for the generation of high charged state metal ion beams is developed. This method is based on microwave heating of vacuum arc plasma in a magnetic trap under electron cyclotron resonance （ECR） conditions. Two gyrotrons for plasma heating were used, which were with the following parameters. The first is with a wave frequency of 37.5 GHz, a pulse duration of 1 ms and power of 100 kW, another is with 75 GHz, 0.15 ms and 400 kW. Two different magnetic traps were considered for vacuum arc plasma confinement. The first one is a simple mirror trap. Such system was already investigated and could provide high charge state ions. The second trap was with a cusp magnetic field configuration with native ＂minimum-B＂ field structure. Two different ways of metal plasma injection into the magnetic trap were used. The first one is an axial injection from an arc source located out of the trap, and the second is a radial injection from four arc sources mounted at the center of the trap. Both traps provide up to 200 eMA of ion beam current for platinum ions with highest charge state 10＋. Ion beams were successfully extracted from the plasma and accelerated by a voltage of up to 20 kV.

Luminescent terphen[3]arene sulfate-activated FRET assemblies for cell imaging

Multicharged supramolecular assemblies based on luminescent macrocycle play an important role in extending their optical properties and functions.Herein,we reported macrocyclic supramolecular assemblies based on luminescent terphen[3]arene sulfate(TP[3]AS)and tetraphenylethylene pyridinium(TPE-4Py)through electrostatic interactions,host-guest encapsulation andπ-πstacking interactions.F?rster resonance energy transfer(FRET)process from TP[3]AS to TPE-4Py was achieved with the energy transfer efficiency of 99.9%,accompanied by TPE-4Py fluorescence emission bathochromic shifted of 15 nm and enhanced by 1.68 times in PBS solution.In contrast,other non-luminescent sulfato-β-cyclodextrin and sulfobutylether-β-cyclodextrin only can enhance the fluorescence intensity of TPE-4Py without bathochromic shift.Due to the strong fluorescence and good stability of TPE-4Py@TP[3]AS,it can be used for optical imaging in living cells,which provided an effective approach for the construction of assembling-confined luminescent biomaterials.

Multiple Ionization of Metal Ions in SMIS 75

A Simple Mirror Ion Source with 75GHz pumping(SMIS 75)has been created.The confinement system is a mirror trap with magnetic field in the plug up to 5T,variable length 15—20cm and mirror ratio 3—5.The plasma of metal ions is injected into the trap by a special vacuum arc minigun.Plasma heating is performed by the microwave radiation of a gyrotron(the frequency of 75GHz,power up to 200kW,pulse duration up to 150μs).The results of the experiment have demonstrated substantial multiple ionization of metal ions.For a metal with high melting temperature(Pt),heating shifts the average ion charge from Pt^(2+) up to Pt^(7+).Maximum stripped observed ion is Pt^(10+).Total current of ion beam is about 300mA.

ECR Plasma with 75GHz Pumping

A Simple Mirror Ion Source with 75GHz pumping(SMIS 75)has been created.The confinement system is a mirror trap with magnetic field in the plug up to 5T,variable length 15—20cm and mirror ratio 3—5.Plasma heating is performed by the microwave radiation of a gyrotron(frequency 75GHz,power up to 200kW,pulse duration up to 150μs).The first results on plasma creation,heating and confinement are presented.Gas discharge conditions and charge state distributions are investigated.The main features of the plasma are high density and short confinement time.Plasma is confined in the trap in quasi-gas-dynamic regime.This means very short rising time and very dense plasma flux.