Search results for "Polyatomic ion"
showing 10 items of 47 documents
Composition dependence ofSi1−xGexsputter yield
2005
Sputtering yields have been measured for unstrained ${\mathrm{Si}}_{1\ensuremath{-}x}{\mathrm{Ge}}_{x}$ $(x=0--1)$ alloys when bombarded with ${\mathrm{Ar}}^{+}$ ions within the linear cascade regime. Nonlinear S-shape dependence of the sputter yield as a function of the alloy composition has been revealed. The dependence is analyzed within the frameworks of the cascade theory conventionally accepted to be the most systematic to date theoretical approach in sputtering. In view of a linear composition dependence predicted for the sputter yield by the cascade theory adapted for polyatomic substrates, the nonlinearity observed in our experiments is shown to be related to the alloying effect on…
A New LA ‐ ICP ‐ MS Method for Ti in Quartz: Implications and Application to High Pressure Rutile‐Quartz Veins from the Czech Erzgebirge
2016
Experimental determination of the pressure and temperature controls on Ti solubility in quartz provides a calibration of the Ti-in-quartz (TitaniQ) geothermometer applicable to geological conditions up to ~ 20 kbar. We present a new method for determining 48Ti mass fractions in quartz by LA-ICP-MS at the 1 μg g−1 level, relevant to quartz in HP-LT terranes. We suggest that natural quartz such as the low-CL rims of the Bishop Tuff quartz (determined by EPMA; 41 ± 2 μg g−1 Ti, 2s) is more suitable than NIST reference glasses as a reference material for low Ti mass fractions because matrix effects are limited, Ca isobaric interferences are avoided, and polyatomic interferences at mass 48 are i…
The MIRS computer package for modeling the rovibrational spectra of polyatomic molecules
2003
International audience; The MIRS spectroscopic software for the modeling of ro-vibrational spectra of polyatomic molecules is presented. It is designed for the global treatment of complex band systems of molecules to take full account of symmetry properties. It includes e cient algorithms based on the irreducible tensor formalism. Predictions and simultaneous data fi tting (positions and intensities) are implemented as well as advanced options related to group theory algebra. Illustrative examples on CH3D, CH4, CH3Cl and PH3 are reported and the present status of data available is given. It is written in C++ for standard PC computer operating under Windows. The full package including on-lin…
Room temperature acid sonication ICP-MS multielemental analysis of milk
2005
Abstract Room temperature acid sonication of milk samples is proposed as a fast alternative methodology for the determination of the total content of 45 elements (Li, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Y, Mo, Ag, Cd, In, Sn, U, Sb, Te, Cs, Ba, Hg, Pb, Bi, Th, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu, Hf and Ta) in milk by inductively coupled plasma mass spectrometry (ICP-MS). The aforementioned procedure involves a 10 min sample pre-treatment. Measurements were made in quantitative and semiquantitative (Totalquant ® ) modes of analysis using Rh as internal standard and Be, Ge, Tb and Re for internal calibration of the equipment in the semiquantitative mode. The…
The Crucial Role of Polyatomic Anions in Molecular Architecture: Structural And Magnetic Versatility of Five Nickel(II) Complexes Derived from A N,N,…
2009
Five new nickel(II) complexes [Ni(2)L(2)(N(3))(2)(H(2)O)(2)] (1), [Ni(2)L(2)(NO(3))(2)] (2), [Ni(2)L(2)(O(2)CPh)(CH(3)OH)(2)]ClO(4).0.5CH(3)OH (3), [Ni(3)L(2)(O(2)CPh)(4)] (4), and [Ni(2)L(2)(NO(2))(2)](n) (5) have been synthesized by using a tridentate Schiff base ligand, HL (2-[(3-Methylamino-propylimino)-methyl]-phenol), and the polyatomic monoanions N(3)(-), NO(3)(-), PhCOO(-), or NO(2)(-). The complexes have been structurally and magnetically characterized. The structural analysis reveals that in all five complexes, the Ni(II) ions possess a distorted octahedral geometry. Complexes 1 and 2 are dinuclear with di-mu-1,1-azido and di-mu(2)-phenoxo bridges, respectively. Complex 3 is also …
Electron impact mass spectra of chlorinated methyl propanoates
1982
The mass spectral fragmentations of all eleven chlorinated methyl propanoates have been studied. Deuterium labelling and metastable ion analysis were used to elucidate the fragmentation mechanism. The molecular ion peaks of all compounds are small, except methyl 3,3-dichloropanoate (38%). In most cases α-cleavage gives the base peak [COOCH3]+, and the loss of a chlorine atom from the molecular ion is characteristic of the 3-chloro, 3,3-dichloro and 3,3,3-trichloro compounds. Metastable ions showed the losses of small neutral molecules such as CH3OH, CH2CO, CO2 and CO from the [MCl]+ ion. α-Cleavage and the loss of Cl˙ gives an intense [MCOOCH3Cl]+˙ peak, which is the base peak in the spectr…
Towards multifunctional magnetic systems through molecular-programmed self assembly of Re(IV) metalloligands
2015
Abstract The molecular-programmed approach based on the use as ligands of tailor-made metalloligands containing stable six-coordinate rhenium(IV) as paramagnetic centres is presented in this review article. A relatively large amount of spin density is covalent-delocalized away from the rhenium to the peripheral atoms of the ligands in the case of the Re(IV) metalloligands, as shown by polarized neutron diffraction experiments and density functional theory calculations. This feature accounts for the significant through space-magnetic interactions that occur in most of its mononuclear species and more interestingly it also explains the strengthening of the magnetic interactions in the heterom…
Studies in organic mass spectrometry. Part 17—Formation of phenol radical ions by rearrangement of the molecular ions of someN-arylthiophenecarboxami…
1995
It has been shown by exact mass measurements and collision-induced dissociation mass-analysed ion kinetic energy spectra that the structure of the m/z 124 ion observed in the mass spectra of N-(4-methoxyphenyl)thiophene-2-carboxamide, N-(4-methoxyphenyl)thiophene-3-carboxamide, N-(4-methoxyphenyl)-5-nitrothiophene-3-carboxamide and N-(4-methoxyphenyl)benzamide is identical with that of the molecular ion of 4-methoxyphenol. This ion becomes abundant in metastable energy window reactions. A probable mechanism for its formation is discussed.
Determination of dissociation energies by use of energy-dependent decay pathway branching ratios
2001
Abstract We present a method for the determination of dissociation energies of polyatomic systems that undergo sequential fragmentation with energy-dependent decay pathway branching. It allows to experimentally determine the dissociation energy of any polyatomic system that shows such fragmentation behaviour without the need for a specific modelling of the system or of its fragmentation process, thus eliminating several systematic errors of traditional methods. The new method has been applied to the sequential fragmentation of Au+14 and Au+16. The resulting dissociation energies are highly accurate and in good agreement with model-free values based on rates of sequential decays.
Metastable ion studies. 4—mass spectral fragmentation and isomerization in the esters of chlorinated propenoic acids
1983
Metastable peaks have been used to study the fragmentation pathways of the methyl and trideuteriomethyl chloropropenoates and chloromethyl propenoate. The molecular ion peaks of the unsaturated esters are more intense than those of the saturated esters, α-Cleavage, [MOCH3]+, produces the base peak in almost all compounds, the relative abundances of the additional peaks being low for chloromethyl propenoate. The losses of H2O, CH3. and COOH. indicate the isomerization of some ionized chloro esters to the chlorinated 2-butenoic acid molecular ions. An intense loss of H2O observed for methyl 2-chloropropenoate indicates its most facile isomerization, [ester]+˙ → [acid]+˙, whereas the isomeriza…