Postacquisition mass resolution improvement in time-of-flight secondary ion mass spectrometry

Good mass resolution can be difficult to achieve in time-of-flight secondary ion mass spectrometry (TOF-SIMS) when the analysis area is large or when the surface being analyzed is rough. In most cases, a significant improvement in mass resolution can be achieved by postacquisition processing of raw data. Methods are presented in which spectra are extracted from smaller regions within the original analysis area, recalibrated, and selectively summed to produce spectra with higher mass resolution than the original. No hardware modifications or specialized instrument tuning are required. The methods can be extended to convert the original raw file into a new raw file containing high mass resolution data. To our knowledge, this is the first report of conversion of a low mass resolution raw file into a high mass resolution raw file using only the data contained within the low mass resolution raw file. These methods are applicable to any material but are expected to be particularly useful in analysis of difficult samples such as fibers, powders, and freeze-dried biological specimens.