Zeros of meromorphic functions of the form ∑ncn(z−tn)2\sum\limits_n \dfrac{c_n}{(z-t_n)^2}

We study zeros distribution for meromorphic functions of the form $\sum\limits_n \dfrac{c_n}{(z-t_n)^2}$, where $\sum\limits_n \dfrac{|c_n|}{|t_n|^2} <\infty$. We prove an analog of the classical Keldysh theorem and discuss a relation between zero-free functions of this form and second order differential equtions with polynomial coefficients

Symbols of truncated Toeplitz operators

We consider three problems connected with coinvariant subspaces of the backward shift operator in Hardy spaces $H^p$: 1) properties of truncated Toeplitz operators; 2) Carleson-type embedding theorems for the coinvariant subspaces; 3) factorizations of pseudocontinuable functions from $H^1$. These problems turn out to be closely connected and even, in a sense, equivalent. The new approach based on the factorizations allows us to answer a number of challenging questions about truncated Toeplitz operators posed by Donald Sarason.Comment: 19 page

Collision-induced dissociation evidence for charge separation and “ball-and-chain” propagation in the addition of 1-butene to C602+

The collision-induced dissociation of the adduct ions C60(C4H8)22+ and C60(C4H8)32+ formed by sequential reactions of C602+ with 1-butene has been investigated by using a selected-ion flow tube (SIFT) apparatus. Experiments at 295 ± 2 K in 0.35 ± 0.02 torr of helium indicated that C602+ adds at least five molecules of 1-butene in a sequential fashion with rates that decrease with the number of molecules added. Collision-induced dissociation experiments in which the downstream sampling nose cone of the SIFT was biased with respect to the flow tube indicated that the adduct ions C60(C4H8)22+ and C60(C4H8)32+ dissociate into C60.+ and (C4H8)2.+ and (C4H8)3.+, respectively. These observations provide evidence for the occurrence of charge separation in the derivatization of C60 dications and support the “ball-and-chain” mechanism first proposed by Wang et al. in 1992 for the sequential multiple addition of 1,3-butadiene to C602+ and C702+

Inductively coupled plasma mass spectrometer with axial field in a quadrupole reaction cell

AbstractA novel reaction cell for ICP-MS with an electric field provided inside the quadrupole along its axis is described. The field is implemented via a DC bias applied to additional auxiliary electrodes inserted between the rods of the quadrupole. The field reduces the settling time of the pressurized quadrupole when its mass bandpass is dynamically tuned. It also improves the transmission of analyte ions. It is shown that for the pressurized cell with the field activated, the recovery time for a change in quadrupole operating parameters is reduced to <4 ms, which allows fast tuning of the mass bandpass in concert with and at the speed of the analyzing quadrupole. When the cell is operated with ammonia, the field reduces ion-ammonia cluster formation, further enhancing the transmission of atomic ions that have a high cluster formation rate. Ni·(NH3)n+ cluster formation in a cell operated with a wide bandpass (i.e., Ni+ precursors are stable in the cell) is shown to be dependent on the axial field strength. Clusters at n = 2–4 can be suppressed by 9, 1200, and >610 times, respectively. The use of a retarding axial field for in-situ energy discrimination against cluster and polyatomic ions is shown. When the cell is pressurized with O2 for suppression of 129Xe+, the formation of 127IH2+ by reactions with gas impurities limits the detection of 129I to isotopic abundance of ∼10−6. In-cell energy discrimination against 127IH2+ utilizing a retarding axial field is shown to reduce the abundance of the background at m/z = 129 to ca. 3 × 10−8 of the 127I+ signal. In-cell energy discrimination against 127IH2+ is shown to cause less I+ loss than a post-cell potential energy barrier for the same degree of 127IH2+ suppression

High pressure synthesis of FeO-ZnO solid solutions with rock salt structure: in situ X-ray diffraction studies

X-ray diffraction with synchrotron radiation has been used for the first time to study chemical interaction in the FeO-ZnO system at 4.8 GPa and temperatures up to 1300 K. Above 750 K, the chemical reaction between FeO and ZnO has been observed that resulted in the formation of rock salt (rs) Fe1-xZnxO solid solutions (0.3 \leq x \leq 0.85). The lattice parameters of these solid solutions have been in situ measured as a function of temperature under pressure, and corresponding thermal expansion coefficients have been calculated.Comment: 9 pages, 2 figures, 1 tabl