Mass Spectrometer?

Question

please give me the detailed process of the MASS SPECTROMETER
thx

Answer 1

First off the sample must be vaporized (i.e in an atomized state). The sample atoms are then Ionized, most commonly by an electron beam, so now they are charged particles; Its important to note that the mass of the ion, and the mass of the atom is negligable (due to the small mass of the electron in comparison to the atom as a whole). The ion is then repelled by an accelerator plate (basicaly a metal plate or filament which is negativley charged. The mass spec chamber is divided into two halves, the one where the sample is introduced, and the one where it is detected. The only way that the ion can move between the two chambers is by passing through a Velocity Selector. A Velocity Selector is basicaly a tunnel, the walls of which are electrically charged, so that an electric field is present in the tunnel. The mass spec assembely is imersed within a magnetic field, which is perpendicular to the electric field. Any charged particle moving in a magnetic field experiences a force upon it, and so the ion (the sample) starts to move in a circular path. Also, the ion experiences a force due to the electric field. The only way for a particle to make it through the Velocity selector without impacting the sides, is for the electric and magnetic forces to be equal (cancelling each other out). This only happens at a specific velocity (which can be determined using the electric and magnetic field strengths). Once in the detection half of the mass spec, only the magnetic field is present and so the ion moves in a circular path; only ions which move in a path with a particular radius can reach the receptor plate. The ion strikes the receptor plate, and due to the it's charge, produces a small DC current to flow through the plate and out of the machine where it is detected by a computer. Due to the fact that you know the magnetic field strength, electric field strength and the radius of the ions path, you can work out it's mass using:

v = E/B
where v is the Velocicty of the ion, E is electric field strength, and B is Magnetic field strength.

F=Bev
where F is Force on the particle due to the magnetic field, e is the charge of an electron, v is velocity.

F=m(v-squared)/r
where F is the force, v velocity and r the radius of the ions path.

These give:

m=Ber/v

The above are actually vector equations, but due to velocity and electric field being perpendicular to the magnetic field, they become simplified into the simple equasions above.

The computer then outputs a spectum of all masses detected, and so it is possible to determine what a given sample is comprised of.
N.B the entire assembley is in vacuum... and techically, this is a physics question!

Answer 2

The Mass Spectrometer is used for measuring relative atomic mass. The process is : -
1. A sample of the substance is placed in to the Mass Spec.r.
2. The sample is bombarded with electrons forming positive ions.
3. The positive ions are accelerated using an electric field.
4. The positive ions are deflected using a magnetic field.
5. The ions of the lighter isotopes/fragments are deflected more that the ions of the heavier isotopes/fragments. This separates different isotopes/fragments.
6. The ions/fragments are detected to produce a MASS SPECTRUM.

Answer 3

A mass spectrometer sorts single-positive ions out into their mass/charge ratio. Since the charge is the same, ions of different masses can be distinguished from one another. With isotopes, the height of the peak is proportional to the abundance, and accurate calculations of the relative atomic mass of an element can be made by measuring these peak heights, multiplying by the mass number concerned, and averaging them.

Answer 4

There are many details that vary between designs of mass spec, but they all have some common elements.

They all vaporize a small sample. break the sample down into ions (by electron bombardment), accelerate the ions towards a magnet, have a detector to analyze the strikes of ions an interperet this strike as a molecular mass.

Answer 5

I remember the term V.I.A.D.D.

V - aporisation, the compound is turn to a gas

I - onisation, high energy neutrons strike the comound breaking it apart

A - cceleration, the newly formed ions are accelerated

D - eflection, the ion are then passed through a magnetic field which bends their paths. The heavier the ion, the less it deflects, the lighter the ion, the more it deflects.

D - etection, the ions hits the detector and and peak is made in correspondance to where the ion has landed.

Answer 6

it is used to measure relative atomic mass
to measure the relative abundancies of isotopes
used to identify compounds,e.g.drug testing.
THE PROCESS
1VAPOURISATION the sample must be converted to gas
2IONISATIONthe sample is bombarded with electrons ,this process knocks es out of the atom
3ACCERLERATION these ions are accelerated towards a negatively charged plate
4SEPERATION a magnetic field is used to deflect the beam of ions
5DETCTION the ions are electronically detected,then the signal is amplified and recorded as a mass spectrum

Answer 7

mass spec is the analysts equivalent of the rainbow