The 7th (2007) Yamazaki-Teiichi Prize Winner Measurement Science and Technology
Development of Multiple-angle Incidence Resolution Spectrometry and Application to Analysis of Molecular Structure in Ultrathin Films.
| Winner | ||
|---|---|---|
| Takeshi Hasegawa | ||
| History | ||
| Mar. 1989 | Graduated from the Department of Chemistry, School of Science and Engineering, Waseda University | |
| Mar. 1991 | Master's Degree, Graduate School of Science, Kyoto University | |
| Apr. 1993 | Assistant Professor of Analytical Chemistry,Kobe Women's College of Pharmacy | |
| Apr. 2001 | Senior Lecturer of Physical Chemistry, Kobe Pharmaceutical University | |
| Apr. 2003 | Associate Professor, Dept. of Applied Molecular Chemistry, College of Industrial Technology, Nihon University | |
| Oct. 2004 | Concurrently acted as researcher at PRESTO, Japan Science and Technology Agency " Structure Function and Measurement Analysis" | |
| Apr. 2006 | Associate Professor, Department of Chemistry, Graduate School of Science and Engineering, Tokyo Institute of Technology | |
| Present | ||
Reason for award
Takeshi Hasegawa has independently created multiple-angle incidence resolution spectrometry (MAIRS) by using a concept of virtual light, which is a conceptually new technique to analyze molecular orientation in ultrathin films.
Conventional infrared transmission and reflection-absorption spectrometries are complementary techniques for surface analysis, and they have widely been used for analysis of anisotropic structure in thin films. The conventional technique, however, requires both infrared transparent and metallic substrates, which is a concern that the largely different surface in terms of dielectric property would influence structure and property of ultrathin films on the substrates. This has long been a big issue thus far. Dr. Hasegawa explored an alternative way to generate surface-normal electric field oscillation on a nonmetallic substrate. His idea is that un-polarized light is irradiated on a substrate with various angles of incidence, and several power spectra are measured. Through an electric-field analysis, he readily obtained a spectrum that corresponded to the virtual-light measurements. To build a new theoretical framework, a regression equation (expansion form of Beer's law) that is used for multivariate analysis has newly been used on his new understanding.
In this manner, he created a unique and cutting-edge measurement technique, which retrieves the complementary in-plane and out-of-plane mode spectra at a time, with which molecular anisotropic structure (orientation) are revealed.
An automated equipment of this technique was equipped with a Fourier transform infrared (FT-IR) spectrometer, and it has been commercialized for user friendly and accurate molecular orientation analysis in a thin film.
MAIRS has a great impact on an analysis of accurate molecular orientation, which is inevitable for designing nano-thin materials that are needed for developing organic semiconductor devices and DNA chips. MAIRS is expected to spread over a wide range of fields rapidly, since it can be used with a FT-IR that is widely available in global laboratories. In fact, a prototype model was introduced by some laboratories in university and industry before the official issue.
Since Dr. Hasegawa published the principle of the technique in 2002, he was invited by international conferences in six countries that involved USA and Europe, and he earned a lot of grants for the study. In addition, a global instrumentation company bought a right to use the patent, which indicates that the technique is practically useful.
For the reasons above, Dr. Hasegawa has been deemed the appropriate recipient of the Seventh Yamazaki-Teiichi Prize in Measurement Science and Technology.
Background of research and development
The new analytical technique developed in the present study is a result on two different backgrounds, which were combined by a unique concept of 'virtual-light measurements' as mentioned below.
Molecular devices made of ultrathin films represented by liquid crystal are fabricated by ordering of functionalized molecules in arrays. Therefore, analytical technique of molecular orientation at a chemical group level can be a fundamental technology for advanced-material development. Infrared (IR) spectroscopy has already been recognized powerful to retrieve molecular information by chemical groups, and various techniques for IR spectroscopy have been proposed for quantitative analysis of molecular orientation. Nonetheless, a priori knowledge of fine optical constants is necessary for the analysis based on optics. Another problem is that two different substrates in terms of dielectric property used in the analysis often make the analysis inaccurate. In this manner, we had a common background that quantitative molecular orientation analysis is difficult for general chemists.
On the other hand, physical laws are formulated by the use of 'equations,' which strictly relates a parameter in the left-hand side to other physical parameters appeared in the right-hand side. Nevertheless, when the physical parameter is an 'observed' variable, a totally different thing happens.
An observed variable involves a portion that cannot be theorized such as noise, which can be formulated by the use of 'regression equation.' Regression equation accompanies a residual term that corresponds to the un-theorized portion. The prizewinner considered that the residual term can be any unrelated factor to the theoretical term, which is not limited to noise. In other words, if only a half portion of the observed variable can be theorized, it could be formulated with the use of a regression equation. He considered this new characteristic of great interest, since it is unique to 'measurement theory,' with which he aimed at developing a novel analytical technique.
Achievements
The two concepts mentioned above have been combined to be one by introducing another new concept of 'virtual light.' 'Virtual light' means a light that has electric-field oscillation parallel to the travelling direction of the light: longitudinal-wave light. If longitudinal-wave light could be used in practical experiments, surface-normal molecular vibrations in a film sample are selectively measured by irradiating the virtual light perpendicularly to the film. To generate surface-normal electric-field oscillation, thus far, the substrate of the film must be metallic and light have to be reflected on the surface. If the virtual light can be available, however, this experimental limit would be removed, and we don't have to use metallic surface for the measurements.
In practice, in place of building a new theoretical framework for the virtual light, 'a portion' of the obliquely transmitted light across the substrate was theorized in a form of linear combination (matrix product), and the rest portion was left un-theorized. As a result, he readily retrieved a spectrum, as if he measured using the virtual light: the world-premier measurements of 'pure surface-normal molecular vibrations' were realized on a 'nonmetallic surface.' This technique simultaneously yields a spectrum of surface-parallel molecular vibrations, which enables us to analyze molecular orientation by comparing to the other surface-normal-mode spectrum.
This technique named 'multiple-angle incidence resolution spectrometry (MAIRS)' has been found powerful for analysis of molecular structure in organic ultrathin films represented by Langmuir-Blodgett films after many experimental results. In addition, the analytical procedures have been automated, which enables us to easily obtain both in-plane and out-of-plane mode spectra at a time, and molecular orientation analysis has been made an easy task like a daily routine work.
Meaning of the achievements
MAIRS was developed by creation of the two novel concepts: virtual-light measurements and building a measurement theory on a regression equation. This idea has proposed a novel concept of light measurements.
In addition, MAIRS has made molecular orientation analysis in a thin film user friendly. In particular, molecular orientation in a polymer thin film with low crystallinity can clearly be depicted with the technique. Therefore, MAIRS is expected to be widely used for analysis of fundamental structure in a molecular device and coating materials, and it would be recognized as a basic technology for material research and development.
