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Author: Ronnie Carroll McMillan Publisher: ISBN: Category : Phase shift (Nuclear physics) Languages : en Pages : 58
Book Description
"The phase shift method of measuring atomic lifetimes is particularly useful because it allows us to make measurements in the steady state mode instead of in the transient mode. High frequency phase shift techniques cause many problems. The equipment, which was designed and built to make low frequency phase shift techniques possible, is shown schematically and discussed. The new experimental techniques employed in our apparatus are a phase multiplier and a unique method of using a photomultiplier as a mixer. In the photomultiplier the final dynode is used as the grid of a triode. The next to the last dynode may be thought of as the cathode of a triode normally used as a mixer. Using the photomultiplier in this fashion, we have a low noise, extremely efficient mixer. The phase multiplier is essential to accurately measure small phase angles. The problems of high frequency techniques are cited and references given. The speed of light was measured as a test of the equipment. The experimental values resulted in a .95 confidence interval containing the generally accepted value of the speed of light in air. The average value measured was (2.937 ± .033) x 108 meters per second, where .033 is the standard deviation for 48 trials. This average value represents an error of 1.61%. From the results we have established the feasibility of this low frequency method of measuring atomic lifetimes"--Abstract, leaves [i-ii].
Author: Ronnie Carroll McMillan Publisher: ISBN: Category : Phase shift (Nuclear physics) Languages : en Pages : 58
Book Description
"The phase shift method of measuring atomic lifetimes is particularly useful because it allows us to make measurements in the steady state mode instead of in the transient mode. High frequency phase shift techniques cause many problems. The equipment, which was designed and built to make low frequency phase shift techniques possible, is shown schematically and discussed. The new experimental techniques employed in our apparatus are a phase multiplier and a unique method of using a photomultiplier as a mixer. In the photomultiplier the final dynode is used as the grid of a triode. The next to the last dynode may be thought of as the cathode of a triode normally used as a mixer. Using the photomultiplier in this fashion, we have a low noise, extremely efficient mixer. The phase multiplier is essential to accurately measure small phase angles. The problems of high frequency techniques are cited and references given. The speed of light was measured as a test of the equipment. The experimental values resulted in a .95 confidence interval containing the generally accepted value of the speed of light in air. The average value measured was (2.937 ± .033) x 108 meters per second, where .033 is the standard deviation for 48 trials. This average value represents an error of 1.61%. From the results we have established the feasibility of this low frequency method of measuring atomic lifetimes"--Abstract, leaves [i-ii].
Author: J Demas Publisher: Elsevier ISBN: 0323157548 Category : Science Languages : en Pages : 289
Book Description
Excited State Lifetime Measurements attempts to assist in clarifying and unifying the many characteristics and definitions of excited state lifetime measurements. The contents of this book are derived from a series of lectures presented to a research group in the University of New Mexico in 1967. The relevance as well as the methods and measurements of data treatment of excited state lifetimes are featured in this book. The first three chapters provide a brief discussion on concepts and applications of excited state lifetime measurements. Experimental methods and systems are also introduced in these chapters. Chapter 4 delves into more complex systems (serial decay kinetics and resonance energy transfer) while Chapter 5 focuses on the method of least squares fitting, its uses, and misuses. Chapters 6 to 8 mainly discuss the convolution integral and its different applications while Chapter 9 gives a more detailed presentation of instrumentation. The last two chapters discuss special errors and approaches to new methodologies regarding the study of the excited state lifetime measurements. The book will be useful to students and scientists including analytical chemists, photochemists, photobiologists, spectroscopists, and physicists.
Author: W. Murray Bullis Publisher: ISBN: Category : Semiconductors Languages : en Pages : 68
Book Description
About 300 papers concerned with the measurement and interpretation of carrier lifetime in semiconductors are listed together with key words and a brief comment for each. Eight types of entries are included: Description of Methods, Analysis of Results, Standard Methods, Experimental Results, Theroetical Models, Auxiliary Procedures and Data, Reviews, and Books. Emphasis is placed on methods of carrying out measurements of carrier lifetime. Hence complete coverage was attempted and nearly two thirds of the entries appear in the first three categories. A large fraction of the papers listed describe the photoconductivity or photoconductive decay methods. The other most popular methods are based on diode characteristics or the photomagnetoelectric effect. In all, 35 methods for measuring carrier lifetime are represented by entries. In addition, representative papers which describe various models for recombination are included together with a number of papers which discuss the influence of surface recombination and trapping phenomena. Auxiliary procedures such as surface preparation, formation of ohmic contacts, control of temperature, and the like are described in some of the entries. Two indexes, a Key Word Index and an Author Index, are provided together with a classification of the various methods for measuring carrier lifetime. (Author).
Author: Grant David Callin Publisher: ISBN: Category : Languages : en Pages : 96
Book Description
An apparatus is presented to measure fluorescent lifetimes of organic substances in aerated solutions. The apparatus employs the phase shift method of measurement, which is useful for determining lifetimes in the range of 10 to the -7th to 10 to the -9th seconds. When a fluorescent substance is irradiated by light modulated bat frequency omega, the fluorescence is modulated at the same frequency but phase-shifted by an angle phi. This angle is measured by the electrical system of the apparatus, and omega is known; the lifetime upsilon is then calcu.ated with the phase shift formula tan phi = omega(upsilon). The phase shift apparatus is described with respect to function, performance, and error sources, and an experimental procedure is recommended for use with the device. The fluorescent lifetime of perylene was measured to evaluate the system performance and found to be 5.1 = 0.5 x 10 to the -9th seconds. This value was in close agreement with that found by Ware for the same substance, using the same method of measurement. (Author).
Author: Joseph R. Lakowicz Publisher: Springer Science & Business Media ISBN: 0306470578 Category : Science Languages : en Pages : 462
Book Description
In this inaugural volume of a new series, experts in the field help biochemists, analytical chemists, spectroscopists, biophysicists, and other specialists keep up with the latest techniques and technologies available in fluorescence spectroscopy.
Author: Ivor L. Simmons Publisher: Springer Science & Business Media ISBN: 1468433245 Category : Science Languages : en Pages : 339
Book Description
Volume 8 in the series Progress in AnaZyticaZ Chemistry presents a selection of the papers given at the 1975 Eastern Analytical Symposium. The analytical chemist is under constant pressure not only from the research chemist whose sampIes he must characterize and control, but also from an ever-increasing group of governmental agencies stimulated by public concern over health and environmental problems, to determine the most sophisticated kinds of compounds as lower and lower levels. The subjects covered in these papers are wide-ranging, from the analysis of incinerator effluents to the determination of drugs in blood, but through them runs a common theme, the appli cation of the latest instrumental techniques to the problems of analysis. The authors show how successful they have been in rising to the analytical challenges pre sented by an increasingly complex world. The editors take this opportunity to thank them for their efforts in producing such excellent papers for publication in so short a time. Dur special appreciation goes to Dr. M. W. Miller, who acted as program chairman, and his team of session chairmen: P. R. Brown, L. J. Cline Love, C. Horvath, J. R. Lindsay, and T. C. Rains.
Author: Sune Svanberg Publisher: Springer Science & Business Media ISBN: 3642185207 Category : Science Languages : en Pages : 603
Book Description
A wide-ranging review of modern spectroscopic techniques such as X-ray, photoelectron, optical and laser spectroscopy, and radiofrequency and microwave techniques. On the fundamental side the book focuses on physical principles and the impact of spectroscopy on our understanding of the building blocks of matter, while in the area of applications particular attention is given to those in chemical analysis, photochemistry, surface characterisation, environmental and medical diagnostics, remote sensing and astrophyscis. The Fourth Edition also provides the reader with an update on laser cooling and trapping, Bose-Einstein condensation, ultra-fast spectroscopy, high-power laser/matter interaction, satellite-based astronomy and spectroscopic aspects of laser medicine.
Author: Ronnie Carroll McMillan
Author: Ronnie Carroll McMillan
Author: J Demas
Author: 
Author: W. Murray Bullis
Author: Grant David Callin
Author: 
Author: 
Author: Joseph R. Lakowicz
Author: Ivor L. Simmons
Author: Sune Svanberg