Improved energy compensation for time-of-flight mass spectrometry.

A model for improved energy compensation in time-of-flight (TOF) mass spectrometry has been developed and tested. This model includes effects of both the acceleration and drift region on mass resolution for surface desorption TOP mass spectrometers that employ ion mirrors to improve mass resolution. Appropriate placement of an additional stage onto the conventional one- and two-stage mirrors provides compensation for flight time spreads, caused by initial ion kinetic energy distributions, in both regions. Experimental results that validate the model calculations are presented for a modified commercial two-stage ion mirror. For example, m/†m for Na(+) was improved from ∼ 100 to ∼ 200 using only a 200-eV drift energy and a 58-cm drift path.