Quadrupole

A experiment to measure the velocity of gravity is been planned. In order to achieve a reasonable signal in the detector, a very massive quadrupole mass is put to rotate at a very high rotation speed. In order to maximize the signal, the mass much be as higher as possible. This work test mass geometries in Finite Element Modeling (FEM) with the goal to maximize the resistance to high rotation speed.

UV–vis photodissociation action spectroscopy is becoming increasingly prevalent because of advances in, and commercial availability of, ion trapping technologies and tunable laser sources. This study outlines in detail an instrumental arrangement, combining a commercial ion-trap mass spectrometer and tunable nanosecond pulsed laser source, for performing fully automated photodissociation action spectroscopy on gas-phase ions. The components of the instrumentation are outlined, including the optical and electronic interfacing, in addition to the control software for automating the experiment and performing online analysis of the spectra. To demonstrate the utility of this ensemble, the photodissociation action spectra of 4-chloroanilinium, 4-bromoanilinium, and 4-iodoanilinium cations are presented and discussed. Multiple photoproducts are detected in each case and the photoproduct yields are followed as a function of laser wavelength. It is shown that the wavelength-dependent partitioning of the halide loss, H loss, and NH3 loss channels can be broadly rationalized in terms of the relative carbon-halide bond dissociation energies and processes of energy redistribution. The photodissociation action spectrum of (phenyl)Ag2+ is compared with a literature spectrum as a further benchmark. Figure ᅟ

The dielectric properties of a fluid composed of molecules possessing both dipole and quadrupole moments are studied based on a model of the Onsager type (molecule in the centre of a spherical cavity). The dielectric permittivity and the macroscopic quadrupole polarizability alpha[Q] of the fluid are related to the basic molecular characteristics (molecular dipole, polarizability, quadrupole, quadrupolarizability). The effect of alpha[Q] is to increase the reaction field, to bring forth reaction field gradient, to decrease the cavity field and to bring forth cavity field gradient. The effects from the quadrupole terms are significant in the case of small cavity size in a non-polar liquid. The quadrupoles in the medium are shown to have small but measurable effect on the dielectric permittivity of several liquids (Ar, Kr, Xe, CH4, N2, CO2, CS2, C6H6, H2O, CH3OH). The theory is used to calculate the macroscopic quadrupolarizabilities of these fluids as functions of pressure and temperature. The cavity radii are also determined for these liquids, and it is shown that they are functions of density only. This extension of Onsager’s theory will be important for non-polar solutions (fuel, crude oil, liquid CO2), especially at increased pressures.

The CLIC Drive Beam Decelerator (DBD) requires 41,848 quadrupoles to keep the beam focused along its length. Due to the stringent heat load requirements of the CLIC tunnel, a permanent magnet (PM) design is under investigation in a collaboration between CERN and STFC Daresbury Laboratory. The design incorporates a novel method of adjustment based on moving PMs. To cover the full length of the decelerator, two families of quadrupoles have been designed. This paper outlines the challenges of building an adjustable PM quadrupole, and explains the features of the two designs and how they will meet the demanding specifications of the CLIC DBD.

ABSTRACT Mass spectrometry is perhaps the key core methodology for proteomics, and the quadrupole mass analyzer is currently the most widely used mass analyzer in proteomic applications of mass spectrometry. The theory of quadrupole mass analyzers (and of the related quadrupole and multipole devices used to confine and transmit beams of ions into and between mass analyzers) can lend valuable insight into practical considerations for effective use of mass spectrometry.