What is a linear quadrupole?

What is a linear quadrupole?

A linear electric quadrupole can be created by superimposing two electric dipoles of opposite orientation so that their positive charges overlap. The electric field from any collection of charges can be obtained from Coulomb’s law by vector addition of the fields from the individual charge elements.

What is an electric quadrupole in physics?

electric quadrupole moments (an electric quadrupole consists of a charge distribution equivalent to a special arrangement of two electric dipoles) that interact with the electric fields that exist at the nuclear sites.

What is meant by electric quadrupole moment?

The nuclear electric quadrupole moment is a parameter which describes the effective shape of the ellipsoid of nuclear charge distribution. By convention, the value of Q is taken to be positive if the ellipsoid is prolate and negative if it is oblate. …

How do you calculate electric quadrupole moment?

While a single charge is a scalar quantity, and a dipole moment is a vector quantity, the quadrupole moment is a second order symmetric tensor. px=∑Qixipy=∑Qiyipz=∑Qizi.

How does a quadrupole work?

The quadrupole consists of four parallel metal rods. Each opposing rod pair is connected together electrically, and a radio frequency (RF) voltage with a DC offset voltage is applied between one pair of rods and the other. Ions travel down the quadrupole between the rods.

Is co2 a quadrupole?

The symmetric molecule carbon dioxide has a permanent electrical quadrupole moment that can be described as two electrical dipoles sitting back-to-back and pointing in opposite directions. In contrast, nitrogen, hydrogen, and methane have much smaller quadrupole moments.

What is the quadrupole moment of a molecule?

The Quadrupolar Phenomenon A molecular quadrupole moment arises from an uneven distribution of charge inside a molecule. Unlike a molecular dipole moment, quadrupole moments cannot be described using two point charges separated by a distance.

What is the value of electric quadrupole moment for spherical nucleus?

For nuclei, the quadrupole moment characterizes the deviation of the charge distribution from sphericity. In spherically symmetric nuclei, it is zero. However, in nonspherical nuclei the quadrupole moment is nonzero.

Which model introduced the idea about quadrupole moment *?

The shell model says that the unpaired nucleon in the odd-A nucleus decides the spin and the parity of the nucleus. Therefore, we expect that that the magnetic moment of the odd-A nucleus is also decided by the unpaired nucleon. Figure 5: Quadrupole moment of nuclei.

For which of the nuclei the quadrupole moment will remain zero?

If the nuclear spin is less than or equal to ℏ, the nuclear quadrupole moment will be zero. If the environment surrounding the nucleus possesses cubic symmetry, the electric field gradient at the nucleus is zero.

How does an electron multiplier work?

An electron multiplier is a vacuum-tube structure that multiplies incident charges. If an electric potential is applied between this metal plate and yet another, the emitted electrons will accelerate to the next metal plate and induce secondary emission of still more electrons.

What is quadrupole mass spectrometer used for?

Quadrupole mass analyzers are often used for targeted, quantitative applications and can be used either to measure one or a few given ions in a mixture, or to scan across a range of m/z values. Depending on the configuration, they can facilitate both MS and MS/MS applications.

How do you make a linear electric quadrupole?

Linear Electric Quadrupole. A linear electric quadrupole can be created by superimposing two electric dipoles of opposite orientation so that their positive charges overlap. This case can be treated analytically and gives some insights into the nature of quadrupole fields.

What is electric quadrupole interaction?

Electric quadrupole interaction is related to the orientation of nonspherical nuclei in the inhomogeneous electric field generated by an asymmetric charge distribution of the surrounding electrons. The resulting hyperfine coupling energy depends on the nuclear quadrupole moment and the electric field gradient (efg) generated by the electrons.

What is an example of a quadrupole?

Electric quadrupole. Contour plot of the equipotential surfaces of an electric quadrupole field. The simplest example of an electric quadrupole consists of alternating positive and negative charges, arranged on the corners of a square. The monopole moment (just the total charge) of this arrangement is zero.

What is the direction of electric field perpendicular to quadrupole?

The electric fieldfrom any collection of charges can be obtained from Coulomb’s lawby vector additionof the fields from the individual charge elements. This has shown that the distant electric field perpendicular to the quadrupole drops off like 1/r4. This 1/r4dependence applies to other directions as well.