H. Shindo et al., ATOMIC-FORCE MICROSCOPIC OBSERVATION OF STEP MOVEMENTS ON NACL(001) AND NAF(001) WITH THE HELP OF ADSORBED WATER, Journal of the Chemical Society. Faraday transactions, 93(6), 1997, pp. 1169-1174
Citations number
10
Categorie Soggetti
Chemistry Physical","Physics, Atomic, Molecular & Chemical
Cleaved (001) faces of NaCl, NaF and LiF single crystals have been obs
erved with atomic force microscopy in air. Spontaneous movements of mo
natomic steps were observed, depending upon relative humidity, with th
e first two crystals. The step speed on NaCl showed a marked increase
at about 60%, while only a gradual increase was observed with NaF. The
step movements on NaCl were not disturbed very much by screw dislocat
ions, but were substantially retarded by surface voids. The presence o
f adsorbed water in two-dimensionally and three-dimensionally condense
d phases is a reasonable explanation for these effects. By fixing the
AFM tip on flat terraces, crystalline blocks were formed on the NaF su
rface. They grew spontaneously, collecting salt from flat parts. The s
alt is pumped from the substrate to the top of the blocks. A mechanism
to explain this is proposed here.