Abstract
Langmuir-Blodgett films of 4-heptoxy-4'-carboxyazobenzene on mica transferred from pure water exhibit novel strip structures consisting of mono-molecular thick straight bands 80 nm wide and more than 100 μm long. To examine a possibility that these bands are self-organized structures of small monolayer clusters, the effects of monovalent ions are investigated. The monovalent ions caused the mesoscopic bands to coagulate. The fraction of coagulated bands was measured as a function of ion concentrations at pH 7.0 by atomic force microscopy. K+ and Cs+ are shown to interact with the mica surface strongly and destabilize the bands by developing the hydration force. Na+ and Li+ cause critical coagulation without destabilization and have the critical concentrations at 3.0 and 1.6 mM, respectively. UV-vis reflection spectroscopy demonstrates that no molecular reorientation deviating from an H-aggregate-like state occurs during coagulation. X-ray photoelectron spectroscopy was used to obtain an adsorption isotherm of Na+. A comparison with a model monolayer described by Poisson-Boltzmann-Stern theory shows that the unusually large Na+ binding occurs prior to the coagulation. A comment is made on the importance of the characteristically large perimeter regions of monolayer clusters making up the band.
| Original language | English |
|---|---|
| Pages (from-to) | 24-30 |
| Number of pages | 7 |
| Journal | Journal of Colloid and Interface Science |
| Volume | 220 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - Dec 1 1999 |
| Externally published | Yes |
Fingerprint
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Biomaterials
- Surfaces, Coatings and Films
- Colloid and Surface Chemistry
Cite this
Rapid coagulation of Langmuir-Blodgett mesoscopic bands on mica by monovalent ions. / Sano, Masahito; Kamino, Ayumi; Shinkai, Seiji.
In: Journal of Colloid and Interface Science, Vol. 220, No. 1, 01.12.1999, p. 24-30.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Rapid coagulation of Langmuir-Blodgett mesoscopic bands on mica by monovalent ions
AU - Sano, Masahito
AU - Kamino, Ayumi
AU - Shinkai, Seiji
PY - 1999/12/1
Y1 - 1999/12/1
N2 - Langmuir-Blodgett films of 4-heptoxy-4'-carboxyazobenzene on mica transferred from pure water exhibit novel strip structures consisting of mono-molecular thick straight bands 80 nm wide and more than 100 μm long. To examine a possibility that these bands are self-organized structures of small monolayer clusters, the effects of monovalent ions are investigated. The monovalent ions caused the mesoscopic bands to coagulate. The fraction of coagulated bands was measured as a function of ion concentrations at pH 7.0 by atomic force microscopy. K+ and Cs+ are shown to interact with the mica surface strongly and destabilize the bands by developing the hydration force. Na+ and Li+ cause critical coagulation without destabilization and have the critical concentrations at 3.0 and 1.6 mM, respectively. UV-vis reflection spectroscopy demonstrates that no molecular reorientation deviating from an H-aggregate-like state occurs during coagulation. X-ray photoelectron spectroscopy was used to obtain an adsorption isotherm of Na+. A comparison with a model monolayer described by Poisson-Boltzmann-Stern theory shows that the unusually large Na+ binding occurs prior to the coagulation. A comment is made on the importance of the characteristically large perimeter regions of monolayer clusters making up the band.
AB - Langmuir-Blodgett films of 4-heptoxy-4'-carboxyazobenzene on mica transferred from pure water exhibit novel strip structures consisting of mono-molecular thick straight bands 80 nm wide and more than 100 μm long. To examine a possibility that these bands are self-organized structures of small monolayer clusters, the effects of monovalent ions are investigated. The monovalent ions caused the mesoscopic bands to coagulate. The fraction of coagulated bands was measured as a function of ion concentrations at pH 7.0 by atomic force microscopy. K+ and Cs+ are shown to interact with the mica surface strongly and destabilize the bands by developing the hydration force. Na+ and Li+ cause critical coagulation without destabilization and have the critical concentrations at 3.0 and 1.6 mM, respectively. UV-vis reflection spectroscopy demonstrates that no molecular reorientation deviating from an H-aggregate-like state occurs during coagulation. X-ray photoelectron spectroscopy was used to obtain an adsorption isotherm of Na+. A comparison with a model monolayer described by Poisson-Boltzmann-Stern theory shows that the unusually large Na+ binding occurs prior to the coagulation. A comment is made on the importance of the characteristically large perimeter regions of monolayer clusters making up the band.
UR - http://www.scopus.com/inward/record.url?scp=0033485382&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0033485382&partnerID=8YFLogxK
U2 - 10.1006/jcis.1999.6526
DO - 10.1006/jcis.1999.6526
M3 - Article
AN - SCOPUS:0033485382
VL - 220
SP - 24
EP - 30
JO - Journal of Colloid and Interface Science
JF - Journal of Colloid and Interface Science
SN - 0021-9797
IS - 1
ER -