ABSTRACT

The principle behind laser ionization time-of-›ight mass spectrometry (LI-TOFMS) is illustrated in Figure 7.1. A measurement sample is introduced into a vacuum chamber, and it is ionized by laser irradiation. The electric —eld potential V is simultaneously applied for acceleration of ions. The accelerated ions enter a region with no potential difference (the drift region) and undergo uniform motion. At this time, due to the law of energy conservation, the ions’ electric —eld potential is equivalent to their kinetic energy. The following formula is established by the energy conservation low:[7.1]

zV m

t = 1 2

(7.1)

where z is the ion value, the length of the drift region, m the ion mass, and t the time of ›ight of the ion traversing the drift region.