Temperature dependent water adsorption on Bi2Sr2CaCu2O8 single crystal

Temperature dependent infrared study of water adsorption on the bc-plane of a Bi2Sr2CaCu2O8 (Bi2212) single crystal reveals that water is molecularly physisorbed, and forms hydrogen-bonded clusters in the temperature range of 85–150 K. Although dissociative adsorption is expected on surfaces terminated with Ca–O and Cu–O groups, no dissociated species is detected. The main absorption bands occur between 3200 and 3500 cm−1 and are assigned to the O–H stretching and the overtone of O–H bending. For exposures higher than 1.0 L, the sticking coefficients are similar for different temperatures. The features in the O–H stretch region for water clusters red-shift as a function of temperature between 85 and 140 K. Water clusters have an amorphous structure between 85 and 140 K, and form a crystalline structure at 150 K.