| Research Abstract |
In this project, we developed high sensitive and high resolute TOF-MS for nano-surface analysis. The aim of our study is to develop the new TOF analyzer system that can analyze chemical composition, chemical structure and chemical state of nano-order sample's surface in atomic or molecule size level, by combining TOF-MS with UHV-STS/STM.
First, we developd the TOF-MS combined UHV-STS/STM after many revisions and trials, Next, by introducing small size pulse ion source to the TOF, we studied TOF-MS based on ion-beam excited dissociation. In addition, we studied and built up the measurement system that can be used laser assist ionization method in which surface of sample was irradiated with laser pulse. Especially, in these cases, about STM measurement, we got basis date about the relation between the current and the distance between tip and sample, by varying bias voltage in wide range. In the laser assist ionization method, we focused the excitation beam of YAG laser at 355 nm onto the top of tip in the STM measurement system. With this treatment, we could find the correlation between the intensity of dissociated ion from the surface of sample and intensity of laser pulse. More over, based on these results, using bias voltage and current of tip as the parameters, we found the relation between parameters and intensity of dissociated ion originated from laser pulse, and got useful knowledge about effective ionization suitable for variable materials.
At present, we are improving the focal electric field and found the optimal condition to develop the efficiency TOF detector, and studying to translate the distribution of desorbed ion into two dimensional picture by tip scanning measurement.
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