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Electron Ionization of Methanol - Born Oppenheimer Potential Curves. In this process, an electron from the analyte molecule (M) is expelled during the collision process to convert the molecule to a positive ion with an odd number of electrons. The following gas phase reaction describes the electron ionization process [10]
The original ionisation event liberates one electron, and each subsequent collision liberates a further electron, so two electrons emerge from each collision to sustain the avalanche. In electromagnetism , the Townsend discharge or Townsend avalanche is an ionisation process for gases where free electrons are accelerated by an electric field ...
This process can be understood as a process by which a bounded electron, through the absorption of more than one photon from the laser field, is ionized. This picture is generally known as multiphoton ionization (MPI). Keldysh [28] modeled the MPI process as a transition of the electron from the ground state of the atom to the Volkov states. [29]
An electron and electron hole (electron-hole pair) can recombine giving up their energy to an electron in the conduction band, increasing its energy. The reverse effect is known as impact ionization. The Auger effect can impact biological molecules such as DNA.
An electron avalanche is a process in which a number of free electrons in a transmission medium are subjected to strong acceleration by an electric field and subsequently collide with other atoms of the medium, thereby ionizing them (impact ionization).
The DART ionization process can produce positive or negative ions depending on the potential applied to the exit electrode. This ionization can occur for species desorbed directly from surfaces such as bank notes, tablets, bodily fluids (blood, saliva and urine), polymers, glass, plant leaves, fruits & vegetables, clothing, and living organisms.
Chemical ionization (CI) is a lower energy process than electron ionization because it involves ion/molecule reactions rather than electron removal. [6] The lower energy yields less fragmentation, and usually a simpler spectrum. A typical CI spectrum has an easily identifiable molecular ion. [7]
Laser-based electrospray-based ambient ionization is a two-step process in which a pulsed laser is used to desorb or ablate material from a sample and the plume of material interacts with an electrospray to create ions. [49] For ambient ionization, the sample material is deposited on a target near the electrospray.