Electrostatic spray ionization

Electrostatic spray assisted vapoin deposition (ESAVD) is a technique to deposit both thin and thick layers of a coating on to various substrates. In simple terms when chemical precursors are sprayed across an electrostatic field towards a heated substrate, the chemicals imdergo a controlled chemical reaction and are deposited on the substrate as the required coating. Electrostatic spraying techniques were developed in the 1950s for the spraying of ionized particles on charged or heated substrates. 

Electroslag remelting, 23 255 Electroslurry process, 23 576 Electrospinning, 11 186 Electrospray ionization, liquid chromatography, 4 625 Electrospray ionization source, 15 654-658 Electrostatic atomization, in spray coating, 7 72-73... 

Electrospray ionization (ESI) refers to the overall process by which an intense electric field disperses a sample liquid into a bath gas as a fine spray of highly charged droplets. Evaporation of those charged droplets produces gas-phase ions by mechanisms that remain the subject of much argument and debate. The ESI is a complex of independent component processes, the two most important of which are electrospray dispersion, the electrostatic dispersion of sample liquid into charged droplets, and ionization, the transformation of solute species in those droplets to free ions in the gas phase. 

The nano-electrospray (nanoES) source is essentially a miniaturized version of the ES source. This technique allows very small amounts of sample to be ionized efficiently at nanoliters per minute flow rates and it involves loading sample volumes of 1-2 pi into a gold-coated capillary needle, which is introduced to the ion source. Alternatively for on-line nanoLC-MS experiments the end of the nanoLC column serves as the nanospray needle. The nanoES source disperses the liquid analyte entirely by electrostatic means [27] and does not require assistance such as solvent pumps or nebulizing gas. This improves sample desolvation and ionization and sample loading can be made to last 30 minutes or more. Also, the creation of nanodroplets means a high surface area to volume ratio allowing the efficient use of the sample without losses. Additionally, the introduction of the Z-spray ion source on some instruments has enabled an increase in sensitivity. In a Z-spray ion source, the analyte ions follow a Z-shaped trajectory between the inlet tube to the final skimmer which differs from the linear trajectory of a conventional inlet. This allows ions to be diverted from neutral molecules such as solvents and buffers, resulting in enhanced sensitivity. 

Figure 9.7 Schematic of Electrospray ionization. A "spray" of droplets is formed that evaporate until the destabilizing electrostatic forces cause the droplets to "explode" releasing multi-charged molecular ion species for mass analysis.

ESP, Electrostatic precipitator IWS, ionizing wet scrubber SDA, spray dryer absorber FF, fabric filter. 

Figure 1 Schematic drawing of an electrospray ionization (ESI) source and a triple-quadrupole mass analyzer. Ions are generated from the spray in the electrostatic field between the capillary and the counterelectrode. They are subsequently transmitted through a number of electrostatic lenses into the high-vacuum region of the first quadrupole mass analyzer (MS1). Optionally, ions selected by MSI can be fragmented by collision-induced dissociation (CIO) with gas (e.g., argon) in the collision cell and fragment ions analyzed in the second quadrupole mass analyzer (MS2). Representative residual pressures are indicated for the different regions of the instrument.

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