H. Byrd et al., LANGMUIR-BLODGETT-FILMS AS SINGLE-LAYER ANALOGS OF KNOWN ORGANIC-INORGANIC SOLID-STATE MATERIALS, Synthetic metals, 71(1-3), 1995, pp. 1977-1980
Langmuir-Blodgett films of manganese octadecylphosphonate (Mn(O3PC18H3
7). H2O) are prepared by depositing octadecylphosphonate monolayers fr
om a MnCl2 . 4H(2)O containing subphase at a pH range of 5.2-5.5. The
LB films possess crystalline order that is analogous to the bulk manga
nese organophosphonates. Pressure versus area isotherms suggest that t
he Mn2+ ions cross-link the phosphonate groups at the air/water interf
ace. Two sharp IR bands at 978 cm(-1) and 1088 cm(-1) can be assigned
to the symmetric and asymmetric PO32- stretching modes, respectively,
and a H2O bending mode at 1608 cm(-1) is also observed. XPS analysis d
emonstrates that the Mn to P ratio is 1 to 1 which is consistent with
the bulk manganese phosphonates. X-ray diffraction yields a layer spac
ing of 48.5 Angstrom. The in-plane structure is determined by transmis
sion electron diffraction (TED). The combined diffraction data yield l
attice parameters for the LB film based on an orthorhombic space group
of a = 5.7 Angstrom b = 48.5 Angstrom and c = 4.9 Angstrom. The in-pl
ane order is analogous to that of the known bulk manganese organophosp
honates. The shape and g-value of the EPR signals for the bulk mangane
se phenylphosphonate and the LB film are identical. Temperature depend
ent magnetic susceptibility of the LB film demonstrates short-range an
tiferromagnetic order with the coherence length of the interaction inc
reasing as the temperature is lowered.