Starting in the 1950s, AT&T has been involved in the design, installation, and operation of undersea coaxial cable systems to provide international and inter-island telecommunication services. These systems are analog transmission systems, utilizing frequency division multiplexing to simultaneously transmit multiple channels over a single cable. With the passage of time, and in response to an ever growing demand for services, the frequency bandwidths of successive systems have been increased to accommodate the need for increased traffic density. The increases in bandwidth have been accompanied by increases in copper ohmic losses, brought about by the skin effect phenomenon, mandating ever shorter spacing between repeaters, and consequently larger numbers of repeaters for a given system length. The reliability outlook for extending coaxial cable technology beyond its present capacity, with a decrease in repeater spacing below the current value of about 9 km, is not favorable.

Fortunately, we now have available optical fibers for transmission media. Unlike coaxial cable, the fiber medium is not limited by the skin effect phenomenon. Using fiber technology, we can transmit large amounts of traffic through a very small cross-sectional areas, using repeaters at infrequent intervals. Moreover, undersea fiber optical systems utilize digital (as opposed to analog) transmission, a format extremely advantageous in terms of transmission quality and the types of services that can be offered.

The generally accepted definition for thermal analysis is that it covers “a group of techniques in which a physical property for a substance and/or its reaction product(s) is measured as a function of temperature while the substance is subjected to a controlled temperature program.” From this broad scope, it is evident that at some point in their careers nearly all experimental materials scientists have been practicing thermal analysts. It is also obvious that the techniques of thermal analysis are applicable to the entire range of materials. Consequently, it is difficult, it not impossible, to properly review such a topic in several pages, but I hope that a carefully selected handful of examples will acquaint the readers with the standard techniques and the enormous versatility inherent in thermal methods. One aspect which simplifies the review is that the methods are conceptionally very simple and do not require extensive descriptions.

Table I describes some of the more common techniques for which examples will be presented. Obviously, many more properties have been studied; however, those listed will suffice as an introduction to the subject.

Because all information derived from thermal methods frequently has only an indirect correlation with the chemical concentration or process of interest, it is important to use more than one technique where possible.

The importance of interfaces for material science and electronic devices has stimulated great interest in the development of surface analytical tools. Among them, modern optical techniques using lasers have attracted the most attention in recent years. They have the advantage of being applicable to all interfaces accessible by light, and the high temporal, spatial, and spectral resolutions offer unique opportunities for studying ultrafast molecular dynamics and other transient phenomena at interfaces. Optical second harmonic generation (SHG) and sum-frequency generation (SFG) are particularly being noticed because of the many recent successful demonstrations of their versatility. This article briefly introduces these newly developed surface probes, first outlining the basic principles behind surface SHG and SFG, and then illustrating the power of the techniques with selected examples. A more complete treatment of the theory can be found in References 4–6. An overview of the earlier applications can be found in Reference 3.

SHG arises from the nonlinear polarization P(2)(2ω) induced in a medium by an incident laser field E(ω). In the electric dipole approximation, P is given by:

where is a second-order nonlinear susceptibility. For a medium with inversion symmetry, it follows directly from Eq. 1 that = 0. However, at an interface the surface nonlinear susceptibility is nonvanishing because there the inversion symmetry is necessarily broken.

The National Nanofabrication Facility began in 1977 out of the scientific community's recognition of a national need for an openly accessible resource in microfabrication. The NNF was then known as the National Research and Resource Facility for Submicron Structures (NRRFSS). In establishing the NRRFSS, Cornell University and the National Science Foundation launched an ambitious experiment both in an advanced technology and in a new research methodology. The current charter of the facility, which differs little from NRRFSS' original charter, is to:

∎ Develop state-of-the-art instrumentation and processes for fabrication and characterization of structures at dimensions below 100 nm.

∎ Provide for both nanofabrication and microfabrication a national facility that is available to any qualified researcher from U.S. universities, industry, and federal laboratories.

∎ Aggressively pursue applications of nanofabrication techniques in a broad spectrum of engineering and scientific disciplines.

∎ Train students, scientists, and engineers in nanofabrication and microfabrication and their applications.

∎ Transfer nanofabrication technology and information to the research and development communities.

To meet these goals, faculty involved with the NRRFSS committed themselves to establishing a world-class research center. They hired staff, purchased equipment, built a new building, attracted new students and faculty, and began innovative research that either utilized microfabrication techniques or advanced those techniques.