Chemical ionization source, the reagent gas is present in large excess compared to the analyte. Electrons entering the source with energy around 200-500 eV will preferentially ionize the reagent gas. Then, the ion/molecule reactions produces more stable reagent ions and the resultant collisions with other reagent gas molecules will create an ionization plasma. Positive and negative ions of the analyte are formed by reactions with this plasma. The following reactions are possible with methane as the reagent gas. If ammonia is the reagent gas, For isobutane as the reagent gas, Self chemical ionization is possible if the reagent ion is an ionized
Positive liberty Berlin described a statement such as "I am slave to no man" as one of negative liberty, that is, freedom from another individual's direct interference. He contrasted this with a Positive Freedom statement such as "I am my own master", which lays claim to a freedom to choose one's own pursuits in life. Charles Taylor sees Negative Freedom as an "opportunity-concept": one possesses Negative Freedom if one is not enslaved by external forces, and has equal access to a society's resources (regardless of how one decides to spend their time). Positive Freedom, says Taylor, is an "exercise-concept": possessing it might