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Basically this section will be electrospray in a nutshell: it will delve into the history of electrospray, and follow its development as a technological tool in modern day scientific circles. The basics of the apparatus will be described, and a simplistic schematic will be generated to represent the core concepts. A very brief overview of its applications will be provided to demonstrate the value and versatility of this piece of equipment. The section will conclude with an iteration of the aims of this article ... to make electrospray more widely available and raise awareness of its remarkable capabilities. | Basically this section will be electrospray in a nutshell: it will delve into the history of electrospray, and follow its development as a technological tool in modern day scientific circles. The basics of the apparatus will be described, and a simplistic schematic will be generated to represent the core concepts. A very brief overview of its applications will be provided to demonstrate the value and versatility of this piece of equipment. The section will conclude with an iteration of the aims of this article ... to make electrospray more widely available and raise awareness of its remarkable capabilities. | ||
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==How it Works== | ==How it Works== | ||
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# Droplet Fission | # Droplet Fission | ||
# Ion Evaporation | # Ion Evaporation | ||
Below, each of these steps will be discussed | Below, each of these steps will be discussed individually and the governing roles that various mechanical and electrochemical factors play will be described. Figure 1 gives an overview of the apparatus setup while actively spraying. | ||
===Onset and Emission=== | ===Onset and Emission=== | ||
Initiation of an electrospray is achieved by applying an electric field to liquid housed in a capillary. The magnitude of the electric field needed, E<sub>onset</sub>, is dependent upon the following relationship: | |||
E<sub>onset</sub> ≈ √((2γcosθ<sub>0</sub>) / (ε<sub>0</sub>r<sub>c</sub>)) | |||
Where: | |||
γ = the surface tension of the solvent | |||
θ<sub>0</sub>; = the cone half angle | |||
ε<sub>0</sub> = the dielectric constant | |||
r<sub>c</sub> = the radius of the emitter orifice | |||
===Droplet Fission=== | ===Droplet Fission=== | ||
===Ion Evaporation=== | ===Ion Evaporation=== | ||
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Describe the nitty gritty physics behind the electrospray process. Such a discussion, from what I have read so far, will have to include an introduction to the basics like ion formation, electric potentials, and surface tension, then progress from these to describe the three main steps (Droplet formation, droplet shrinkage, gaseous ion formation) as identified in [http://www.wiley.com/legacy/wileychi/ms/articles/677_a.pdf 1]. Depending upon time constraints, etc., this theory section may be expanded to describe phenomena resulting from usage of electrospray, such as microencapsulation and its use in facilitating DNA entry through the cell membrane in gene therapy. | Describe the nitty gritty physics behind the electrospray process. Such a discussion, from what I have read so far, will have to include an introduction to the basics like ion formation, electric potentials, and surface tension, then progress from these to describe the three main steps (Droplet formation, droplet shrinkage, gaseous ion formation) as identified in [http://www.wiley.com/legacy/wileychi/ms/articles/677_a.pdf 1]. Depending upon time constraints, etc., this theory section may be expanded to describe phenomena resulting from usage of electrospray, such as microencapsulation and its use in facilitating DNA entry through the cell membrane in gene therapy. | ||
Revision as of 18:01, 24 March 2008
Introduction
Electrospray is a phenomenon that results from the application of an electric field to fluid contained in a small capillary. The driving electrostatic force incites the emission of droplets that cycle through phases of evaporation and coulombic explosion, ideally resulting in the formation of gas-phase ions or a very fine liquid aerosol. Though this technique has found widespread use in the area of mass spectrometry, it has also been documented to function in a wide range of other applications such as industrial painting, particle deposition, and gene therapy.
This wide array of modern uses, however, belies the fact that the basic science behind electrospray is anything but new. Indeed, it can trace its origins all the way back to Lord Rayleigh's article, "On the equilibrium of liquid conducting masses charged with electricity" published in 1882.[1] A little over 30 years thereafter, John Zeleny became the first man to witness an electrospray event, and subsequently published his observations in "The electrical discharge from liquid points, and a hydrostatic method of measuring the electric intensity at their surfaces."[1] Since then, continuing research by Taylor, Fenn, Dole, and a number of other researchers have continued to push forward science's understanding and range of applications for electrospray.[1],[2]
How it Works
As a process, the literature segregates the electrospray event into a series of 3 unique phases:[3]
- Onset and Emission
- Droplet Fission
- Ion Evaporation
Below, each of these steps will be discussed individually and the governing roles that various mechanical and electrochemical factors play will be described. Figure 1 gives an overview of the apparatus setup while actively spraying.
Onset and Emission
Initiation of an electrospray is achieved by applying an electric field to liquid housed in a capillary. The magnitude of the electric field needed, Eonset, is dependent upon the following relationship:
Eonset ≈ √((2γcosθ0) / (ε0rc))
Where:
γ = the surface tension of the solvent θ0; = the cone half angle ε0 = the dielectric constant rc = the radius of the emitter orifice
Droplet Fission
Ion Evaporation
Making Electrospray a Reality
Material Requirements
Tools
Construction
Operation
Working and Innovating with Electrospray
References
- ↑ 1.0 1.1 1.2 Salata OV. 2005. Tools of nanotechnology: electrospray. Curr Nanosci 1(1): 25-33.
- ↑ Gaskell SJ. 1997. Electrospray: principles and practice. J Mass Spectrom 32:677-688.
- ↑ Rohner TC, Lion N, Girault HH. 2004. Electrochemical and theoretical aspects of electrospray ionisation. Phys Chem Chem Phys 6:3056-3068.