A new time-of-flight SIMS instrument for 3D imaging and analysis

We have built a mass spectrometer which utilizes a new method of time-of-flight analysis to provide rapid data acquisition with simultaneous high spatial resolution and high mass resolution. The mass analysis is performed by sampling the secondary beam into a two-stage time-of-flight system. This removes the requirement for a pulsed primary beam as a ToF reference. No tradeoff exists between spatial and mass resolution, and acquisition speed is not limited by the primary beam duty cycle. The analyzer comprises the combination of a shaped field buncher and a nonlinear reflectron. This configuration allows the inclusion of a collision cell and an intermediate time-of-flight selection gate. So, the analyzer can operate in ms-ms mode as well as in normal time-of-flight mode. The instrument is equipped with 40 kV C60 and liquid metal cluster primary beams, which can run in d.c. mode, or, when charge neutralization is required, in slow pulsed mode. Data acquisition is continuous, eliminating loss of data during depth profiling etch cycles. The instrument has an automated sample entry system with heating to 670 K and cooling to 105 K, and includes a novel method of freeze-fracture for tissue samples or other organic samples in aqueous suspension. Copyright (C) 2010 John Wiley & Sons, Ltd.