When, in the spring of 1979, H.P. Baltes presented me with the precursor of this vo 1 ume, the book on "Inverse Source Problems in Opti cs," I expressed my gratitude in a short note, 11hich in translation, reads: "Dear Dr. Ba ltes, the mere titl e of your unexpected gift evokes memori es of a period, which, in the terminology of your own contribution, would be described as the Stone Age of the Inverse Problem. Those were pleasant times. Walter Kohn and I lived in a cave by ourselves, drew pictures on the walls, and nobody seemed to care. Now, however, Inversion has become an Industry, which I contemplate with as much bewilderment as a surviving Tasmanian aborigine gazing at a modern oil refinery with its towers, its fl ares, and the confus i ng maze of its tubes." The present volume makes me feel even more aboriginal - impossible for me to fathom its content. What I can point out, however, is one of the forgotten origins of the Inverse Scattering Problem of Quantum Mechanics: Werner Heisenberg's "S-Matrix Theory" of 1943. This grandiose scheme had the purpose of eliminating the notion of the Hamiltonian in favour of the scattering operator. If Successful, it would have done away once and for all with any kind of inverse problem.

Semiconductor performance is often characterized in terms of the rate at which its carrier recombination processes occur. Carrier recombination, including radiative, and Schockley-Read-Hall and Auger (both nonradiative), occurs at ultra-fast times in the picosecond or femtosecond regimes. A device which can measure both spectral data and temporal phenomena at this speed is the streak camera. The capability to do time-resolved spectroscopy of wide band gap semiconductors using a streak camera has been established at AFIT for the first time. Time resolved photoluminescence (TRPL) from samples of gallium nitride were measured at temperatures of 5 K over spectral bands of 36.6 A and temporal ranged of 45 to 1970 ps, both instrument-limited. TRPL features at 3552 A and 3587 A were studied giving decay lifetimes at 43.2 plus or minus 1.6 ps and 16.8 plus or minus 3.4 ps, respectively. Shockley-Read-Hall, Radiative and Auger coefficients were found but parameterized in terms of experimental efficiency, n, which was not measured. These values, determined using a least-squares-error fit of the carrier recombination rate equation to collected data, are -9.3*10 9 plus or minus 4.9*10 8 s -1, 7.5*10 17 n plus or minu 8.0*10 19 n cm 3/s, and 1.8*10 25 n 2 plus or minus 8.6*10 27 n 2 cm 6/s respectively, for the first peak and -2.5*10 10 plus or minus 5.2*10 9 s -1, 4.9*10 19 n plus or minus 2.0*10 19 n cm 3/s and -1.4*10 28 n 2 plus or minus 8.6*10 27 n 2 cm 6/s for the second peak. Since alignment of the streak camera has not yet been optimized, large but unquantified uncertainty in these results exists. Isolating vibratiosn and improving streak camera alignment should reduce the uncertainty and permit data collection temporally resolved at hundreds of femtoseconds.

This book focuses on studying the growth, properties and applications of inorganic, organic and molecular thin films. Inorganic thin films are important for semiconductor circuits, photovoltaic devices and protective coatings. Organic thin films play a critical role in chemical sensors, optical liquid crystal displays and in surface chemistry on atmospheric aerosols. Molecular solid films are essential in understanding heterogeneous atmospheric chemistry on cloud and aerosol particles. This book brings together new and exciting research in this field.