Temperature-programmed desorption spectrometer combining minimum gas load, fast substrate replacement, and comprehensive temperature control

Abstract

With the capability of quantitative identifying surface species and measuring desorption kinetics, temperature-programmed desorption (TPD) is widely used in heterogeneous catalysis and surface science fields. Minimum gas load during adsorption, fast substrate replacement, and comprehensive temperature control are of great significance for efficient and high quality TPD experiments. Unfortunately, these requirements usually cannot be met at the same time for the existing apparatuses in surface science. In order to increase the universality, a TPD spectrometer combining minimum gas load, fast substrate replacement, and comprehensive temperature control in our laboratory has been built. By using an automatically controlled microcapillary array-based effusive molecular beam gas doser, optimizing the thermal contact at the sample stage, using liquid nitrogen transfer line and designing thermocouple connection, controllable and reproducible molecule adsorption, minimum gas load, fast substrate replacement, rapid cooling, accurate temperature measuring and excellent linear heating are achieved simultaneously. Capabilities of the TPD spectrometer, for example, determination of desorption energy and desorption order, quantitative measurements of surface species and binding sites, and investigation of surface photochemical reactions, are demonstrated by measuring the desorption of water from highly oriented pyrolytic graphite and TiO2(110) and photocatalyzed oxidation of methoxy anions on TiO2(110). The apparatus described here will contribute effectively to the high throughput measurements.