(1) A clean vacuum can be obtained and the background of hydrocarbons is extremely small.
(2) Start-up time / shut-down time is very short.

A turbomolecular pump is a clean vacuum pump suitable as the main pump of a mass spectrometer. The blades of a turbomolecular pump (TMP), rotating with high speed, for example 60,000 RPM, hit gas molecules down and remove gas from the vacuum chamber.

Turbomolecular Pump