NA AND CL-2 INTERACTION ON 1T AND 2H-TASE2(0001) SURFACES

Ln this paper we study the interaction of Cl-2 and Na on 1T-TaSe2 and 2H-TaSe2(0001) surfaces in the temperature range of 100-300 K. The exp eriments are performed in UHV with the use of LEED and SXPS by synchro tron radiation measurements. Deposition of Na on Cia-covered 1T-TaSe2 at 100 K forms initially a Na-Cl-2(-) which with increasing temperatur e to 300 K leads to NaCl formation. Adsorption of Cl-2 on Na-intercala ted 1T and PH-TaSe2 surfaces at 100 K forms Cl-2 multilayers. The firs t Cl-2 layer, in contact with the substrate, interacts with the Na nea r the surface and forms NaCl2-. Warming up to 300 K leads to partial d esorption of Cia, while the remaining chlorine interacts strongly with Na, causing the deintercalation of Na to the surface in the tendency to form NaCl. The intercalation-deintercalation process takes place ac ross the van der Waals planes and it is much faster on 2H than on 1T-T aSe2, which is attributed to the different crystal structure of 2H and 1T of TaSe2.