Michael A. Dillon

Bio: Michael A. Dillon is an academic researcher from Argonne National Laboratory. The author has contributed to research in topics: Excited state & Rydberg formula. The author has an hindex of 20, co-authored 69 publications receiving 1743 citations.

HIGH-RESOLUTION STUDY OF ELECTRON-IMPACT SPECTRA AT KINETIC ENERGIES BETWEEN 33 AND 100 eV AND SCATTERING ANGLES TO 16--.

Abstract: An electrostatic lens system which compensates for chromatic aberration has been tested in an electron spectrometer. The results indicate that this lens is suitable for comparisons of peak intensities in electron‐impact spectra. Relative intensities in vibrational progressions that belong to a single electronic transition have been studied in N2, CO, and NH3 and found to be nearly independent of the scattering angle. Electron‐impact spectra have been reported for helium, nitrogen, oxygen, argon, nitric oxide, nitrous oxide, ammonia, water vapor, carbon dioxide, ethylene, acetylene, and benzene at electron kinetic energies between 33 and 100 eV. Spectral regions of special interest are encountered in CO2 and C6H6. At excitation energies of 7–10 eV in CO2 a change in intensity distribution, attributed to transition from an electric‐quadrupole to an electric‐dipole spectrum, is observed as the kinetic energy is raised. In the case of C6H6 a change in the spectrum with angle is encountered which strongly sugg...

Generalized Oscillator Strength for 11S→21P Transition of Helium. Theory of Limiting Oscillator Strengths

Abstract: Relative generalized oscillator strengths have been determined for the 11S→21P transition in helium as a function of momentum change of the colliding electron and normalized to the theoretical oscillator strength {calculated by Schiff and Pekeris [Phys Rev 134, A638 (1964) ]} at zero momentum change The validity of the normalizing procedure is investigated theoretically and it is shown that the limit of the generalized oscillator strength at zero momentum change is equal to the optical oscillator strength for any atom or molecule at any incident energy regardless of whether the first Born approximation holds The normalizing procedure is therefore justified The results are compared with the experimental and theoretical oscillator strengths obtained by other investigators The limiting relation for oscillator strengths is established under much more general conditions than in any previous research

A collision cross section study of the 1 1S → 2 1P and 1 1S → 2 1S transitions in helium at kinetic energies from 200–700 eV. Failure of the Born approximation at large momentum changes

Abstract: Differential collision cross sections have been determined for the 1 1S → 2 1S and 1 1S → 2 1P transitions in helium at scattering angles within the range 7.5°−35° and kinetic energies of 200, 300, 400, 500, and 700 eV. Multiple scattering errors have been eliminated by determining the ration of inelastic to elastic cross section as a function of pressure (the dependence is linear) and extrapolating to zero pressure. The error in the absolute cross sections is less than 5% in most instances. Where large corrections for multiple scattering are necessary the error bound is 6%. Generalized oscillator strengths (f) have been calculated from the data for both transitions and compared with the Born approximation calculations (fB) of Kim and Inokuti [Phys. Rev. 175, 176 (1968)]. At a scattering angle of 30° the ratio fB/f (which would be unity if the Born approximation were accurate) decreases from the value 0.86 at 200 eV to 0.16 at 500 eV for the transition 1 1S → 2 1P. At smaller values of the squared momentu...

Use of stable oxygen and carbon isotope analyses for monitoring the pathways and rates of intrinsic and enhanced in situ biodegradation

Abstract: Significant challenges remain in developing reliable techniques to monitor in situ biodegradation. Stable carbon and oxygen isotope analyses of the contaminants, products of degradation, and electron acceptor(s) may provide robust means for monitoring the occurrence, pathways, and rates of intrinsic or enhanced in situ biodegradation. Results of a laboratory study using diesel fuel and a mixed microbial culture show that combined stable carbon isotope analyses of carbon dioxide and stable oxygen isotope analyses of molecular oxygen allow monitoring of the occurrence and pathways of degradation. The first-order rate constants for contaminant degradation (about −0.04 day-1) obtained from oxygen and contaminant concentrations are in excellent agreement with those obtained from isotopic data for oxygen (−0.04 to −0.05 day-1), indicating that oxygen isotope analyses of molecular oxygen can be used for quantifying the rate of contaminant degradation. Based on our results and a review of the published literature...

Kinetics of diffusion-controlled processes in liquids. theoretical consideration of luminescent systems: quenching and excitation transfer in collision

Abstract: The over‐all behavior of reacting particles in solution is determined both by specific molecular properties and by probability of encounter This paper presents an examination of the effect of the details of diffusion and locally inhomogeneous distributions on the over‐all behavior of a system of reacting particles both for steady‐state conditions and for the decay (or relaxation) phenomena subsequent to creation of an initial conditionThe problem is formulated for the quenching of excited molecules in solution in terms of diffusion equations for excited and quencher molecules with appropriate initial and boundary conditions The diffusion equations are solved for a completely determined, but otherwise arbitrary, initial distribution of quencher molecules around an excited molecule and two sets of boundary conditions: the so‐called Smoluchowski and ``radiation'' boundary conditions The resultant equations give, in their turn, expressions for decay of excited molecules for initial random distributions fo

Principles of fluorescence spectroscopy

Abstract: Fluorescence methods are being used increasingly in biochemical, medical, and chemical research. This is because of the inherent sensitivity of this technique. and the favorable time scale of the phenomenon of fluorescence. 8 Fluorescence emission occurs about 10- sec (10 nsec) after light absorp tion. During this period of time a wide range of molecular processes can occur, and these can effect the spectral characteristics of the fluorescent compound. This combination of sensitivity and a favorable time scale allows fluorescence methods to be generally useful for studies of proteins and membranes and their interactions with other macromolecules. This book describes the fundamental aspects of fluorescence. and the biochemical applications of this methodology. Each chapter starts with the -theoreticalbasis of each phenomenon of fluorescence, followed by examples which illustrate the use of the phenomenon in the study of biochemical problems. The book contains numerous figures. It is felt that such graphical presentations contribute to pleasurable reading and increased understand ing. Separate chapters are devoted to fluorescence polarization, lifetimes, quenching, energy transfer, solvent effects, and excited state reactions. To enhance the usefulness of this work as a textbook, problems are included which illustrate the concepts described in each chapter. Furthermore, a separate chapter is devoted to the instrumentation used in fluorescence spectroscopy. This chapter will be especially valuable for those perform ing or contemplating fluorescence measurements. Such measurements are easily compromised by failure to consider a number of simple principles."

Inelastic Collisions of Fast Charged Particles with Atoms and Molecules-The Bethe Theory Revisited

Abstract: Since the appearance of the title paper, a number of new developments have occurred which need to be included in that body of material. We present additional remarks and clarifications which supplement and update numerous aspects of the Bethe theory discussed in the earlier paper. We also bring the bibliography up to date. Plasma stopping power, the ${z}^{3}$ effect, and stopping power for particles at extreme relativistic energies are among the new topics included. We make several comments on Fano's earlier review article, Ann. Rev. Nucl. Sci. 13, 1 (1963).

Stochastic approach to chemical kinetics

Abstract: In this article we shall present a summary of the various stochastic approaches and applications to chemical reaction kinetics, but before discussing these we first briefly introduce the basic ideas and definitions of classical or deterministic chemical kinetics. One of the basic questions to which chemists address themselves is the rate of chemical reactions, or in other words, how long it takes for a chemical reaction to attain completion, or equilibrium. Apparently the first significant quantitative investigation was made in 1850 by L. Wilhelmy [93]. He studied the inversion of sucrose (cane sugar) in aqueous solutions of acids, whose reaction is He found empirically that the rate of decrease of concentration of sucrose was simply proportional to the concentration remaining unconverted, i.e., if S(t) is the concentration of sucrose, then The constant of proportionality is called the rate constant of the reaction. If S o is the initial concentration of sucrose, then Since then an enormous number of reactions has been studied and the field of chemical kinetics is now one of the largest areas of chemical research. The importance of the field lies in the fact that it yields concise expressions for the time dependence of reactions, predicts yields, optimum economic conditions, and gives one much insight into the actual molecular processes involved. The detailed molecular picture of a reaction process is called the mechanism of the reaction.

Resonances in Electron Impact on Diatomic Molecules

Abstract: In this review we present the energies, configuration, and other properties of resonances (also called "compound states" and "temporary negative ions") in diatomic molecules. Much of the information is presented in the form of tables and energy level diagrams. Vibrational, rotational, and electronic excitation are discussed whenever these processes have given information on resonances; often these excitation processes proceed via resonances. The paper is divided according to molecular species (${\mathrm{H}}_{2}$, ${\mathrm{N}}_{2}$, CO, NO, ${\mathrm{O}}_{2}$), but the main conclusions are discussed by the nature of the processes involved.

Inelastic collisions of fast charged particles with atoms and molecules the Bethe theory revisited

Abstract: Since the appearance of the title paper, a number of new developments have occurred which need to be included in that body of material. We present additional remarks and clarifications which supplement and update numerous aspects of the Bethe theory discussed in the earlier paper. We also bring the bibliography up to date. Plasma stopping power, the ${z}^{3}$ effect, and stopping power for particles at extreme relativistic energies are among the new topics included. We make several comments on Fano's earlier review article, Ann. Rev. Nucl. Sci. 13, 1 (1963).