Design and construction of a semiautomatic temperature programmed desorption apparatus for ultrahigh vacuum

A computer-controlled system that allows acquisition of large volumes of temperature programmed desorption data under ultrahigh vacuum conditions has been designed and tested. The vacuum part of the system consists of a sample mounted on a rotation–translation manipulator, a shielded quadrupole mass spectrometer for the desorption flux measurement, and a collimated molecular beam doser for adsorbate delivery. The experiment involves a series of tasks: (1) dosing of the adsorbate onto the surface; (2) calibration of the mass spectrometer gain; (3) translating the dosed sample to the mass spectrometer position; (4) linearly ramping the temperature of the sample to acquire the desorption spectrum; and (5) cooling the sample. In the system described here, these tasks are accomplished automatically. As a result, the time needed for the experiment and the potential for operator errors are substantially reduced. The performance of the system is demonstrated for CCl4 adsorbed on gold-supported single wall carbon nanotubes.