Site: National Institute for Advanced Interdisciplinary Research (NAIR)
Cluster Science Group
1-1-4 Higashi
Tsukuba, Ibaraki 305, Japan
Tel: (81) 298-54 2540; Fax: (81) 298-54 2949

Date Visited: 23 July 1997

WTEC: D.M. Cox (report author), H. Goronkin, E. Hu, J. Mendel, H. Morishita

Host:

• Dr. Harutoshi Takeo, Leader of Cluster Science Group
  E-mail: takeo@nair.go.jp

BACKGROUND

NAIR, the National Institute for Advanced Interdisciplinary Research is one of 15 research institutions of AIST, the Agency of Industrial Science and Technology. The focus of the AIST laboratories is concentrated on R&D programs judged to be capable of raising the level of Japan's technology in four main ways:

1. nurture new leading-edge technology that will lay the basis for future technical innovation
2. establish basic technical standards
3. meet the society's needs for earthquake prediction, pollution prevention, and environmental preservation
4. embrace all basic or general research that is appropriate for a national research organization

NAIR was founded in January 1993 with an objective of pursuing interdisciplinary research themes covering fundamental and frontier areas of industrial science. The institute is dedicated to the creation of international intellectual properties in broad fields of basic and strategic R&D, where national funds are expected to play a positive role. NAIR is characterized by the tripartite collaboration of industrial, academic, and governmental sectors, as well as by international cooperation. It is portrayed as an innovative attempt to overcome institutional boundaries by bringing together scientists of diversified specialty ¾ not only from research institutes under AIST and the Science and Technology Agency (STA), but also from universities and research organizations in the private sector ¾ to engage in intensive joint research.

RESEARCH AND DEVELOPMENT HIGHLIGHTS

NAIR had four main research projects at the time of the WTEC visit:

1. The Atom Technology Project. This project has as its goal the ultimate technology for manipulating atoms and molecules; it started in January 1993 and runs until March 2002; total budget is ¥25 billion.
2. Research on Cluster Science Project. The goal of this project was experimental and analysis of the character of clusters; it ran from January 1993 until March 1998; total budget was ¥1 billion.
3. Research on Bionic Design Project. The goal of this project was to advance understanding in cell and tissue engineering and molecular machines; it ran from January 1993 until March 1998; total budget was ¥1 billion.
4. Basic Research on Next Generation Optoelectronics. The goal of this project is large capacity optical memory; this is a new program with seed money first available in April 1996; start date appeared to be April 1998, running until March 2003; total budget in April 1996 was ¥80 million for defining program goals and directions.

In addition to the above projects, NAIR has carried out several two- to three-year feasibility studies since its formation in 1993. The Atom Technology Project is the subject of a separate review in the JRCAT site report (p. x of Appendix D). The remainder of this report will focus on the Research on Cluster Science Project.

RESEARCH ON CLUSTER SCIENCE

Dr. Harutoshi Takeo, the Cluster Science Group Leader, greeted the WTEC panel and first presented an overview of the science projects in his group, then led the panel on a tour of the laboratories. The cluster group consists of about 30 researchers, with nine regular research staff members, seven staff members on assignment from other AIST institutes, one from a university, 9-11 postdoctoral fellows, of which seven or eight are foreigners, and two to three graduate students. To further broaden the perspectives of the Cluster Science Group, it organizes a yearly workshop to which it invites 15-20 outside researchers. Over the lifetime of the project over 90 outside scientists will have participated in and contributed to these workshops.

The Cluster Science Group's research areas fall roughly into four areas:

1. clusters in collisionless environments (molecular beams)
2. clusters in liquid or solution
3. clusters stabilized on surfaces or in matrices
4. clusters stabilized in a nanocage such as a zeolite

In the collisionless environment the main activities are focused on probing the structure and reactivity of clusters under single collision conditions. The research facilities, which have been designed and built entirely from scratch since mid-1993, include a Fourier transform ion cyclotron resonance mass spectrometer with which cluster structures are studied via laser spectroscopy; cluster chemical reactivity is being probed through controlled introduction of various molecular species. A second apparatus, a cluster beam system, combines infrared pumping of molecular adsorption on clusters with resonantly enhanced multiphoton ionization techniques to interrogate cluster and molecular bonding. Bonding of aniline and aniline dimers to a variety of different molecules has been studied.

To study the properties of liquid clusters, an expansion liquid droplet source together with a time-of-flight mass spectrometer (reflectron mode) was built. Study of mixtures of water/ethanol solutions have shown an evolution from clusters consisting of mostly water molecules complexed with one or two ethanol molecules for high concentration of water in the mixture, to clusters consisting of mostly ethanol molecules complexed with one or two water molecules when the ethanol concentration in the mixture reaches 40% or more. Such studies allow fundamental intermolecular interactions of molecules in liquids to be investigated.

To probe the properties of clusters on supports, several sophisticated pieces of experimental apparatus were built. One especially impressive experiment uses a liquid metal source (heated crucible) to produce clusters that are deposited on a cryogenic substrate in order to stabilize them. The apparatus is interfaced with an X-ray source. The substrate with different cluster deposits is rotated in-situ, allowing X-ray determination of the structure to be investigated as a function of the metal type, the cluster size, the substrate material, and the temperature. Interestingly, gold clusters with size < 6 nm are found to have icosahedral structure and not the fcc structure of bulk gold. Upon warming the substrate, the clusters sinter and the development of the fcc structure can be followed as a function of temperature. Studies of gold-copper alloy clusters also show icosahedral structure for clusters less than about 6 nm. Several other metal and metal alloy systems will be examined.

To investigate the quantum properties of nanometer-sized materials, the Cluster Science Group is attempting to stabilize metal clusters in the channels of zeolites. Specifically they have put sodium into the channels of an LTA zeolite in the hopes of producing a quantum wire. The sodium-doped materials have been shown to exhibit photochromic behavior, exhibiting reversible darkening upon exposure to light. In contrast, potassium-doped zeolites investigated by another group exhibited ferromagnetic behavior.

One of the researchers has developed a terahertz spectrometer capable of probing molecular vibrations in the 15-30 cm^-1 range. At the time of the WTEC visit, this spectrometer appeared ready to be applied to real problems.

CONCLUDING REMARKS

In the short time it has existed, the NAIR cluster group has put together some of the best approaches of any group in Japan to study fundamental science issues. They began with virtually no equipment in 1993 and have designed and built a series of sophisticated apparatuses, each focused on probing a specific fundamental issue of cluster science. The unfortunate event was the termination of this effort in March of 1998. In this particular instance, the researchers are just beginning to harvest the results of careful and thoughtful design of state-of-the-art equipment. In at least one instance the apparatus was just coming on line at the time of the panel's visit, and that particular scientist will have only a few months to generate data before termination of the program.

It was the WTEC panel's perception that several of the researchers (almost all fairly young) did not yet have positions to which they could move. Some of the older researchers obviously will be able to return to their sending organization, but several were hired directly into this project and had no ties to any outside organization. We were informed that each researcher will be allowed to keep his equipment in the new position, which is certainly good news, but "the termination of the program" was a theme that had certainly raised the anxiety level of many of the staff. The quality of the research and the novelty with which these young researchers have approached science could serve as a model for other groups in Japan; namely, the researchers were allowed (even encouraged) to identify interesting cluster science problems and then design experimental apparatus to probe these problems, rather than to just buy equipment. This appears to have born fruit, but the fruit may dry up before harvest can occur.