The ''photovoltaic promise'' is that this solar technology is good for our nation's energy supply, good for our environment, good for our economy, and good for our future. This FAQ sheet briefly discusses details in each of these four areas. It also explains the federal role in solar electricity, specifically, the U.S. Department of Energy's PV Program, whose twofold purpose is to accelerate the development of PV as a global energy option and to assure U.S. technology and global market leadership.

The National Photovoltaic (PV) Program, a joint effort of DOE, the national laboratories, and the U.S. PV industry, had exciting advances and significant accomplishments in fiscal year 1997. The booklet provides details of new products introduced, manufacturing processes improved, capacity expanded, and new materials explored. The Million Solar Roofs Initiative, announced by President Clinton on June 26, 1997, will build on the solid foundation of steady research progress in laboratories and universities, industry investment in new technology and capacity, and the burgeoning solar power market both here and abroad.

An innovative partnership between government and industry has been awarded the prestigious R&D 100 Award for developing a new biomass gasification technology. Based on research sponsored by the U.S. Department of Energy, the technology demonstrates how biomass can be converted into a clean burning gaseous fuel for firing advanced power systems with high efficiencies and low emissions. The award is given yearly by R&D magazine to the 100 most significant technical achievements of the year.

Synchrotron radiation is a very bright, broadband, polarized, pulsed source of light extending from the infrared to the x-ray region. It is an extremely important source of Vacuum Ultraviolet radiation. Brightness is defined as flux per unit area per unit solid angle and is normally a more important quantity than flux alone particularly in throughput limited applications which include those in which monochromators are used. It is well known from classical theory of electricity and magnetism that accelerating charges emit electromagnetic radiation. In the case of synchrotron radiation, relativistic electrons are accelerated in a circular orbit and emit electromagnetic radiation in a broad spectral range. The visible portion of this spectrum was first observed on April 24, 1947 at General Electric's Schenectady facility by Floyd Haber, a machinist working with the synchrotron team, although the first theoretical predictions were by Lienard in the latter part of the 1800's. An excellent early history with references was presented by Blewett and a history covering the development of the utilization of synchrotron radiation was presented by Hartman. Synchrotron radiation covers the entire electromagnetic spectrum from the infrared region through the visible, ultraviolet, and into the x-ray region up to energies of many 10's …

A short review of the application of surface x-ray scattering techniques to the electrode/electrolyte interfaces is presented. Recent results on metal, halide, and metal-halide adlayers with three specific systems: Bi on Au(100) and Au(110); Br on Au(100) and Ag(100); and the coadsorption of Tl with Br or I on Au(111), are given as an illustration. Factors affecting ordering of pure metal and halide adlayers and the metal-halide surface compounds are discussed in some detail.

The voltage or electric potential difference across the terminals of a cell when no current is drawn from it. The emf of a cell is the sum of the electric potential differences (PDs) produced by a separation of charges (electrons or ions) that can occur at each phase boundary (or interface) in the cell. The magnitude of each PD depends on the chemical nature of the two contacting phases. Thus, at the interface between two different metals, some electrons will have moved from the metal with a higher free energy of electrons to the metal with a lower free energy of electrons. The resultant charge separation will produce a PD (just as charge separation produces a voltage across a capacitor) that, at equilibrium, exactly opposes further electron flow. Similarly, PDs can be produced when electrons partition across a metal/solution interface or metal/solid interface, and when ions partition across a solution/membrane/solution interface.