Chemical Imaging of Fingerprint on RMB Banknotes Using Time-of-Flight Secondary Ion Mass Spectrometry

The development of latent fingerprints on long-circulated RMB banknotes has been one of the difficulties in forensic science research. In this work, time-of-flight secondary ion mass spectrometry (TOF-SIMS) was used to perform chemical imaging of latent fingerprints on the surfaces of the substrates due to its advantages such as in-situ, quasi-nondestructive, high-throughput, simultaneous analysis of multi-components and high spatial resolution. The developing effect of TOF-SIMS was firstly compared with that of several traditional methods, and the reasons for the unique advantages of TOF-SIMS were discussed. Secondly, its applicability was further discussed from the perspective of universality, sensitivity and fingerprint three-level feature acquisition capability. Finally, exogenous substances in fingerprints were also analyzed by using this technique to detect the molecular ions (m/z 92.06) and fragment ion peaks (m/z 43.02) of glycerol in the moisture lotion and developed clear fingerprint images. Preliminary research results showed that TOF-SIMS technique could provide an effective method for the development of latent fingerprints on long-circulated RMB banknotes and was expected to be used for the detection of substances in fingerprints on the surface of the substrates.