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In mass spectrometry, direct analysis in real time (DART) is an ion source that produces electronically or vibronically excited-state species from gases such as helium, argon, or nitrogen that ionize atmospheric molecules or dopant molecules. The ions generated from atmospheric or dopant molecules undergo ion-molecule reactions with the sample ...
The electrode geometry is chosen so that, under the given physical parameters (pressure, ignition voltage, gas constant, see Paschen's law), flexibility regarding the plasma medium is ensured. This allows the generation of stable cold plasma even in ambient air. In the simplest application, ambient air can be directly analyzed.
Atmospheric pressure chemical ionization chamber cross section. Atmospheric pressure chemical ionization (APCI) is an ionization method used in mass spectrometry which utilizes gas-phase ion-molecule reactions at atmospheric pressure (10 5 Pa), [1] [2] commonly coupled with high-performance liquid chromatography (HPLC). [3]
Atmospheric pressure photoionization (APPI) is a soft ionization method used in mass spectrometry (MS) usually coupled to liquid chromatography (LC). Molecules are ionized using a vacuum ultraviolet (VUV) light source operating at atmospheric pressure (105 Pa), either by direct absorption followed by electron ejection or through ionization of a ...
Although atmospheric pressure MALDI is performed under ambient conditions, [15] it is not generally considered to be an ambient mass spectrometry technique. [ 16 ] [ 17 ] Laser ablation was first coupled with mass spectrometry in the 1980s for the analysis of metals using laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS ...
The pH range is commonly given as zero to 14, but a pH value can be less than 0 for very concentrated strong acids or greater than 14 for very concentrated strong bases. [2] The pH scale is traceable to a set of standard solutions whose pH is established by international agreement. [3]
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Solid and liquid activities do not depend very strongly on pressure because their molar volumes are typically small. Graphite at 100 bars has an activity of only 1.01 if we choose p o = 1 bar as standard state. Only at very high pressures do we need to worry about such changes. Activity expressed in terms of pressure is called fugacity.