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Multiple-angle incidence resolution spectrometry (MAIRS) that was originally developed in an infrared region for analysis of molecular orientation in a thin film on a substrate has been extended to develop a novel UV-visible spectrometry. The new technique, named Vis-MAIRS, has been employed for analysis of anisotropic surface plasmon excitation in a silver thin film with a thickness of 5 nm deposited on a glass slide. The Vis-MAIRS spectra yield two spectra at a time, which correspond to absorption spectra whose transition moments are parallel and perpendicular to the film surface. The two spectra of the silver thin film were largely different from each other in shape, which strongly suggested that the silver nanoparticles in the thin film were in an ellipsoidal shape. In addition, absorption due to long-range surface plasmon propagation across the nanoparticles aligned parallel to the film surface, which is a result of the dipole or quadruple couplings of plasmon in each particle, was clearly monitored for the first time in the Vis-MAIRS spectra. In this manner, Vis-MAIRS is expected to be a useful tool to study aggregates of metal nanoparticles in a film.

A long-time issue that thin films supported on a substrate with low refractive index cannot be subjected to multiple-angle incidence resolution spectrometry (MAIRS) has been resolved, and an advanced MAIRS technique has been developed. Infrared multiple-angle incidence resolution spectroscopy (IR MAIRS) is being recognized as a powerful spectroscopic tool for revealing molecular orientation in thin films or molecular adsorbates. MAIRS has been, however, employed with only IR spectroscopy thus far, since MAIRS requires high refractive index substrates such as germanium and silicon, and shorter wavelength regions have no appropriate substrates. Although one of the most commonly useful substrates for IR spectroscopy is Ca[F.sub.2], unfortunately it cannot be employed for IR MAIRS because of the low refractive index. To overcome this experimental limitation, the principle of MAIRS has been studied theoretically, and it has been found that polarization effects on transmission intensity is the main cause that disturbs a proper MAIRS analysis. As a result, now it is possible to employ IR MAIRS for analysis of thin films on Ca[F.sub.2] by removing the s-polarization and by use of the advanced MAIRS algorithm.

Gibbs monolayers of lipophilic tetraphenylporphyrinatomanganese(III) and hydrophilic diacid of meso-tetrakis-(4-sulfonatopheny)porphyrin adsorbed at the liquid--liquid interface have been analyzed by UV--visible external reflection (ER) and partial internal reflection (PIR) spectra measured at different angles of incidence. The angle-dependent ER and PIR spectra over the Brewster angles ([[theta].sup.ER.sub.B] and [[theta].sup.IR.sub.B]) have readily been measured at the toluene/water interface. As preliminarily expected in our previous study, the present study has first proved that the reflection--absorbance of UV--visible PIR spectra quantitatively agrees with the theoretical calculations for the Gibbs monolayer over [[theta].sup.IR.sub.B]. In addition, it has also been proved that the absorbance of the PIR spectra is greatly enhanced in comparison to that of the ATR spectra. The enhancement is caused by an optical effect in the monolayer sandwiched between two phases of toluene and water that have different but refractive indices close to each other. This optical enhancement requires an optically perfect contact between the phases, which is difficult to prepare for a solid--solid contact. At the liquid/liquid interface, however, an ideal optical contact is easily realized, which makes the enhancement as much as the theoretical expectation. The PIR spectrometry will be recognized to be a new high-sensitive analytical tool to study Gibbs monolayer at the liquid/liquid interface.

Infrared multiple-angle incidence resolution spectroscopy (IR MAIRS) has been employed for the structural analysis of a heterogeneous multilayer Langmuir--Blodgett (LB) film of ketomycolic acid (keto-MA). Keto-MA was chosen for the study because the molecule changes its conformation largely, which depends on the layer structure of the LB film: the long alkyl chain with a keto group remains folded when it has no counter layer for interdigitation. IR MAIRS is a surface analytical technique that was originally developed to analyze anisotropic structure in a thin film prepared on an IR transparent material. In the present study, however, a newly found characteristic of MAIRS has been used to discuss the molecular conformation and the interdigitation architecture between two adjacent monolayers. As expected theoretically, the molecular folding was clearly detected as 'IR MAIRS shift'. Subtraction of the IR MAIRS spectra of single- and triple-monolayer LB film of keto-MA yielded unambiguous results for the interdigitated double layer in the triple-monolayer LB film, and the layer sequence was also revealed.

Molecular orientation analysis in a single monolayer deposited on a glass substrate has been a difficult matter, since the glass substrate absorbs infrared rays so strongly that the measurements of infrared spectra are difficult to perform, and the single monolayer is not suitable for X-ray diff action analysis because no periodical structure is available. When a thin glass is used as the substrate, in particular, the infrared analysis becomes more difficult, since optical fringes appear strongly on the absorption spectra due to the multiple reflections in the glass. In the present study, infrared multiple-angle incidence resolution spectrometry (MAIRS) has been employed to remove the fringes from the spectra of single- and five-monolayer Langmuir-Blodgett (LB) films of cadmium stearate deposited on a thin glass plate. The MAIRS in-plane spectra gave quantitatively reliable infrared transmission spectra for both films with little fringes, which made it possible for the first time to analyze the molecular orientation in the single-monolayer LB film on glass. As a result, it has been revealed that the molecule in the single-monolayer LB film on thin glass exhibits a significantly larger molecular tilt angle than those prepared on other substrates such as gold and germanium.

Multiple-angle incidence resolution spectroscopy (MAIRS) has been improved to be an advanced algorithm so that the Cartesian structure in organic thin films can be analyzed. The infrared MAIRS technique was originally proposed as a totally new spectroscopic technique to reveal structural anisotropy in thin films on an infrared-transparent substrate, which yields both in-plane-(IP; X and Y) and out-of-plane (OP; Z)-mode spectra from an identical sample. Since this technique employs an analytical concept based on a signal decomposition of light intensity (not absorbance spectra), the algorithm intrinsically has high potential for further development. In the present study, the theoretically deduced matrix that correlates the light intensity to the angle of incidence has been modified to further decompose the IP-mode spectrum into X and Y components. As a result, anisotropic measurements of infrared spectra of thin film have become possible for the X, Y, and Z directions (Cartesian coordinate) simultaneously. With this advanced algorithm, the Cartesian structural changes in a cast film prepared on a germanium substrate have readily been analyzed, and a change from the biaxial to the uniaxial film structure with aging has spectroscopically been revealed.

A unique monolayer that has a novel film architecture is constructed by controlling a balance of hydrogen-bonding force and monolayer compression pressure, which is characterized by infrared multiple-angle incidence resolution spectroscopy (MAIRS) that has been recently developed. The study suggests that the strongly correlated physical parameters are useful to develop a new film architecture.

A novel measurement technique of pure out-of-plane vibrational modes of thin films on a nonmetallic substrate has recently been proposed, which is named multiple-angle incidence resolution spectrometry (MAIRS). Since this technique could not be replaced by other conventional techniques, MAIRS was expected to be a promising tool for analysis of thin soft materials and surface adsorbates. Nevertheless, some experimental conditions have been found to be inappropriate for MAIRS, which yields incorrect results. In the present study, therefore, the problems in the technique have been investigated in terms of optics to improve the accomplishments of MAIRS. The problems have been found to have a strong relationship with optics in FT-IR, which is influenced by refractive index of the sample material and angle of incidence. In particular, optimization of the size matching of the detector surface and the infrared spot at the detector was a key to having MAIRS perform properly. It has been concluded that reliable MAIRS measurements require overfilling of the detector and a substrate with a high-refractive index.