a time-of-flight mass spectrometer (tof-ms) developed in our laboratory at isfahan university of technology is described here. the tof-ms instrument uses laser as the ionization source which provides an opportunity to investigate the ions formed in laser ablation or desorption. the tof-ms has an ionization chamber containing an accelerator and an ion lens to focus the ions into a one meter line...

6 Contents Introduction The advantage of radioisotopic standards compared to other physical standards is the independence of their properties from outer conditions. They are neither sensitive to temperature change nor to progress of time. They serve as influence-free-etalon. That is why their use is advantageous in fundamental research, where high precision is required. For instance in direct n...