Collection of Summaries

This article should be read in conjunction with Chapter 3, Electron Ionization.  

In a high vacuum (low pressure 10 mbar), molecules and electrons interact to form ions (electron ionization, El). These ions are usually injected into the mass spectrometer analyzer section. 

Still under vacuum but at higher pressure (typically KT mbar), the initially formed ions collide with neutral molecules to give dilferent kinds of ions before they are injected into the analyzer. As an example, at low pressure, methane gas (CH4) is ionized to give molecular ions (CH4 ) but, at higher pressures, these ions collide with other CH4 molecules to give carbonium ions (CH5+). 

If a substance (M) is under investigation, its molecules can collide with CH, with transfer of a proton (H ) to give [M + H]+, which can be called quasi-molecular or protonated molecular ions. 

Because this chemical reaction occurs between the and M species, the original methane (CH4) is called a reagent gas, the CH5+ species are reagent gas ions, and the process is known as chemical ionization (Cl). 

---

Tanaka H., Tanaka K., Obana S., Tsujimoto A., Tamaru H., Takahama K. The self-cleaning performance of photocatalytic cleaning glass CLEARTECT and its evaluation. In collection of summaries of the 9th Photocatalyst Symposium Summaries, Photo-Eunctionalized Materials Society, Tokyo University, December 2002, pp. 198-199... 

Material Safety Summary Sheets - OHS is a comprehensive collection of summaries of material safety data sheets. The database contains information on more than 52000 chemicals, including pure substances and mixtures. The Summary Sheets are prepared from the information contained in the full Material Safety Data Sheets. The summary Sheets are useful to satisfy regulatory and safety laws by providing an... 

---