Monitoring preparation and phase transitions of carburized W(1 1 0) by reflectance difference spectroscopy

Reflectance difference spectroscopy (RDS) is applied to follow in situ the preparation of clean and carburized W(1 1 0) surfaces and to study the temperature-induced transition between the R(15 × 3) and R(15 × 12) carbon/tungsten surface phases. RDS data for this transition are compared to data obtained from Auger-electron spectroscopy and low-energy electron diffraction. All techniques reveal that this transition, occurring around 1870 K, is reversible with a small hysteresis, indicating a first-order-like behaviour. The present results also prove a high surface sensitivity of RDS, which is attributed to the excitation of electronic p-like surface resonances of W(1 1 0).