Numerical Optimization of a Fully Cross-Coupled Rectifier Circuit for Wireless Passive Ultra Low Power Sensor Nodes.

In the context of the Internet of Things, billions of devices-especially sensors-will be linked together in the next few years. A core component of wireless passive sensor nodes is the rectifier, which has to provide the circuit with sufficient operating voltage. In these devices, the rectifier has to be as energy efficient as possible in order to guarantee an optimal operation.

Doubly charged coronene clusters-Much smaller than previously observed.

The smallest doubly charged coronene cluster ions reported so far, Cor, were produced by charge exchange between bare coronene clusters and He [H. A. B.

Isomeric Broadening of C Electronic Excitation in Helium Droplets: Experiments Meet Theory.

Helium is considered an almost ideal tagging atom for cold messenger spectroscopy experiments. Although helium is bound very weakly to the ionic molecule of interest, helium tags can lead to shifts and broadenings that we recorded near 963.5 nm in the electronic excitation spectrum of C solvated with up to 100 helium atoms.

Resonant electron attachment to mixed hydrogen/oxygen and deuterium/oxygen clusters.

Low energy electron attachment to mixed (H)/(O) clusters and their deuterated analogs has been investigated for the first time. These experiments were carried out using liquid helium nanodroplets to form the clusters, and the effect of the added electron was then monitored via mass spectrometry. There are some important differences between electron attachment to the pure clusters and to the mixed clusters.

Positively and Negatively Charged Cesium and (C) Cs Cluster Ions.

We report on the formation and ionization of cesium and CCs clusters in superfluid helium nanodroplets. Size distributions of positively and negatively charged (C) Cs ions have been measured for ≤ 7, ≤ 12. Reproducible intensity anomalies are observed in high-resolution mass spectra.

Anionic Hydrogen Cluster Ions as a New Form of Condensed Hydrogen.

We report the first experimental observation of negatively charged hydrogen and deuterium cluster ions, H_{n}^{-} and D_{n}^{-}, where n≥5. These anions are formed by an electron addition to liquid helium nanodroplets doped with molecular hydrogen or deuterium. The ions are stable for at least the lifetime of the experiment, which is several tens of microseconds.

Communication: Dopant-induced solvation of alkalis in liquid helium nanodroplets.

Alkali metal atoms and small alkali clusters are classic heliophobes and when in contact with liquid helium they reside in a dimple on the surface. Here we show that alkalis can be induced to submerge into liquid helium when a highly polarizable co-solute, C, is added to a helium nanodroplet. Evidence is presented that shows that all sodium clusters, and probably single Na atoms, enter the helium droplet in the presence of C.

Observation of stable HO4(+) and DO4(+) ions from ion-molecule reactions in helium nanodroplets.

Ion-molecule reactions between clusters of H2/D2 and O2 in liquid helium nanodroplets were initiated by electron-induced ionization (at 70 eV). Reaction products were detected by mass spectrometry and can be explained by a primary reaction channel involving proton transfer from H3(+) or H3(+)(H2)n clusters and their deuterated equivalents. Very little HO2(+) is seen from the reaction of H3(+) with O2, which is attributed to an efficient secondary reaction between HO2(+) and H2.

Building Carbon Bridges on and between Fullerenes in Helium Nanodroplets.

We report the observation of sequential encounters of fullerenes with C atoms in an extremely cold environment. Experiments were performed with helium droplets at 0.37 K doped with C60 molecules and C atoms derived from a novel, pure source of C atoms.

Fission of multiply charged alkali clusters in helium droplets - approaching the Rayleigh limit.

Electron ionization of helium droplets doped with sodium, potassium or cesium results in doubly and, for cesium, triply charged cluster ions. The smallest observable doubly charged clusters are Na9(2+), K11(2+), and Cs9(2+); they are a factor two to three smaller than reported previously. The size of sodium and potassium dications approaches the Rayleigh limit nRay for which the fission barrier is calculated to vanish, i.

Experimental evidence for the influence of charge on the adsorption capacity of carbon dioxide on charged fullerenes.

We show, both experimentally and theoretically, that the adsorption of CO2 is sensitive to charge on a capturing model carbonaceous surface. In the experiment we doped superfluid helium droplets with C60 and CO2 and exposed them to ionising free electrons. Both positively and negatively charged C60(CO2)n(+/-) cluster ion distributions are observed using a high-resolution mass spectrometer and they show remarkable and reproducible anomalies in intensities that are strongly dependent on the charge.

Electron-Induced Chemistry of Cobalt Tricarbonyl Nitrosyl (Co(CO)NO) in Liquid Helium Nanodroplets.

Electron addition to cobalt tricarbonyl nitrosyl (Co(CONO) and its clusters has been explored in helium nanodroplets. Anions were formed by adding electrons with controlled energies, and reaction products were identified by mass spectrometry. Dissociative electron attachment (DEA) to the Co(CO)NO monomer gave reaction products similar to those reported in earlier gas phase experiments.

The interaction of He(-) with fullerenes.

The effects of interactions between He(-) and clusters of fullerenes in helium nanodroplets are described. Electron transfer from He(-) to (C60)n and (C70)n clusters results in the formation of the corresponding fullerene cluster dianions. This unusual double electron transfer appears to be concerted and is most likely guided by electron correlation between the two very weakly bound outer electrons in He(-).

Formation of dianions in helium nanodroplets.

The formation of dianions in helium nanodroplets is reported for the first time. The fullerene cluster dianions (C60)n(2-) and (C70)n(2-) were observed by mass spectrometry for n≥5 when helium droplets containing the appropriate fullerene were subjected to electron impact at approximately 22 eV. A new mechanism for dianion formation is described, which involves a two-electron transfer from the metastable He(-) ion.

On subthreshold ionization of helium droplets, ejection of He(+), and the role of anions.

The mechanism of ionization of helium droplets has been investigated in numerous reports but one observation has not found a satisfactory explanation: How are He(+) ions formed and ejected from undoped droplets at electron energies below the ionization threshold of the free atom? Does this path exist at all? A measurement of the ion yields of He(+) and He2(+) as a function of electron energy, electron emission current, and droplet size reveals that metastable He*(-) anions play a crucial role in the formation of free He(+) at subthreshold energies. The proposed model is testable.