Faculty Profiles - TANAKA Kentaro

Papers - TANAKA Kentaro

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Evaluation of a Transfer Process for Langmuir-Blodgett Films by Means of a Quartz-Crystal Microbalance

Yoshio Okahata, Katsuhiko Ariga, Kentaro Tanaka

Thin Films Vol. 20 page： 317-329 1995.1

Quartz Crystal Microbalance and UV-Vis Absorption Study of Q-State CdS Particle Formation in Cadmium Arachidate Langmuir-Blodgett Films

Robert S. Urquhart, D. Neil Furlong, Herman Mansur, Herman Mansur, Franz Grieser, Franz Grieser, Kentaro Tanaka, Kentaro Tanaka, Yoshio Okahata, Yoshio Okahata

Langmuir Vol. 10 page： 899-904 1994.3

Publishing type：Research paper (scientific journal)

The formation of Q-state CdS particles in cadmium arachidate (CdAr) Langmuir-Blodgett films has been monitored using the quartz crystal microbalance (QCM) and UV-vis absorption measurements. QCM studies showed that the mass uptake of different thickness CdAr films on exposure to hydrogen sulfide was consistent with that expected for the quantitative conversion of Cd2+ ions in the films to CdS and the corresponding conversion of CdAr to arachidic acid. UV-vis absorbance measurements showed an optical blue shift typical of particles between 2 and 3 nm in diameter. Complimentary electron microscopic studies showed a polydisperse size distribution of CdS particles. The most common particle size observed in the electron micrographs was found to be close to the particle size determined from the optical properties of the semiconductor particles. There was a linear relationship between the mass uptake of a film on H2S exposure and changes in its absorption properties due to Q-state particle formation. The linear relationship was used to calculate the optical extinction coefficient of the Q-state particles in the film. Mass uptake measurements on CdAr films extensively exposed to H2S gas showed that the arachidic acid molecules left after Q-state particle formation could be quantitatively converted to CdAr by immersing the film in a stirred aqueous solution containing cadmium chloride. Subsequent reexposure of the film to H2S increased the mole fraction of CdS in the film. © 1994, American Chemical Society. All rights reserved.

DOI： 10.1021/la00015a047

Scopus

Size-quantised cadmium sulfide particles in Langmuir-Blodgett films: Film thermal stability

D. Neil Furlong, Robert Urquhart, Franz Grieser, Franz Grieser, Kentaro Tanaka, Kentaro Tanaka, Yoshio Okahata, Yoshio Okahata

Journal of the Chemical Society, Faraday Transactions Vol. 89 page： 2031-2035 1993.12

Publishing type：Research paper (scientific journal)

The fabrication of particles in Langmuir-Blodgett films of cadmium icosanoate and nonacosa-10,12-diynoate is followed using a quartz crystal microbalance. The mass changes accompanying the exposure of the film to hydrogen sulfide are consistent with a chemical reaction in the film which also produces the acid form of the surfactant. Film thermal stability is greatly reduced after the particles are formed, a result also consistent with formation of the more volatile acid form. The extent of film removal by heating/outgassing suggests that particles are capped by adsorbed icosano or diynoic acid. It is likely that this capping plays a role in particle growth control.

DOI： 10.1039/FT9938902031

Scopus

GROWTH OF CDS PARTICLES IN CADMIUM ARACHIDATE FILMS - MONITORING BY SURFACE-PLASMON RESONANCE, UV-VISIBLE ABSORPTION-SPECTROSCOPY, AND QUARTZ-CRYSTAL MICROGRAVIMETRY International journal

NJ GEDDES, RS URQUHART, DN FURLONG, CR LAWRENCE, K TANAKA, Y OKAHATA

JOURNAL OF PHYSICAL CHEMISTRY Vol. 97 ( 51 ) page： 13767 - 13772 1993.12

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC

The growth of Q-state CdS particles during exposure of Langmuir-Blodgett films of cadmium arachidate to hydrogen sulfide has been monitored by surface plasmon resonance (SPR), UV-visible absorption, and quartz crystal microbalance (QCM) measurements. The growth kinetic profile, expressed in terms of increasing refractive index (SPR), absorption or mass increase (QCM), was the same when films were gassed under similar conditions. Microgravimetry showed the quantitative conversion of Cd2+ to CdS in such systems; UV-visible absorption exhibited the blue shift typical of Q-state particles of 2-3-nm diameter. SPR reflectance curves obtained after H2S treatment were initially fitted assuming that either the film thickness or the real component of the relative permittivity (epsilon(r)) was constant during Q-state particle formation. Film thickness changes (assuming epsilon(r) was constant) were similar to those previously reported. Relative permittivity changes, determined assuming the film thickness was constant, indicated that for thinner films (i.e., fewer than about 10 layers) effects such as film breakup during particle;formation and HS exposure to the gold surface of the SPR crystal were important. The change in epsilon(r) for a 20-layer cadmium arachidate film after-extensive gassing was calculated using Maxwell-Garnett theory. Use of this value in the fitting routine indicated that the film thickness change during particle formation was 0.13 nm/layer or 4.9%.

DOI： 10.1021/j100153a054

Web of Science

Scopus

Evaluation of a horizontal lifting method of Langmuir-Blodgett films using a quartz-crystal microbalance

Y. Okahata, K. Ariga, K. Tanaka

Thin Solid Films Vol. 210-211 page： 702-706 1992.4

Publishing type：Research paper (scientific journal)

A quartz-crystal microbalance (QCM) was employed as a substrate for a horizontal lifting method of various LB films, in which the QCM plate was touched to monolayers on a subphase and lifted horizontally. The transferred mass of monolayers on the QCM could be measured directly at a nanogram level from a frequency decrease of the QCM plate: two monolayers were deposited each cycle (Y-type, transfer ratio 2). The QCM method gave more precise transfer information than the conventional method using the moving area of the barrier on the trough. It was found by the QCM method that Y-type horizontal lifting methods could be widely applied for most monolayers to form well-layered LB films, compared with the conventional vertical dipping method. © 1992.

DOI： 10.1016/0040-6090(92)90379-P

Scopus

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