CH ENGR 104C Lecture Notes - Lecture 3: Mass Spectrometry, Mass Spectrum, Radical Ion

• School: UCLA
• Department: Chemical Engineering
• Course: CH ENGR 104C
• Professor: Dr.Patrick Wen

Document Summary

Mass spectrometry has a number of applications in organic chemistry, including: Finding out the structure of an unknown substance. Verifying the identity and purity of a known substance 1. Step 1: the sample is vaporized, and then ionized by being bombarded by a beam of high- energy electrons (usually at 70 ev). The electron beam knocks out an electron from the molecule of the injected sample, creating a molecular ion (which is also a radical cation because it has an unpaired electron and a positive charge). Losing an electron weakens the bond, while the collision gives it extra kinetic energy. These factors make it more likely for the molecular ion to break into fragments as it travels through the mass spectrometer. Step 2: there is a pair of oppositely charged plates in the ionization chamber. The positively charged one causes the positively charged radical cation to accelerate into an analyzer tube.