Basic Molecular Spectroscopy

P. A. Gorry, BASIC Molecular Spectroscopy, Keigaku Publishing, Tokyo, 1987. 

The quantum theory of spectral collapse presented in Chapter 4 aims at even lower gas densities where the Stark or Zeeman multiplets of atomic spectra as well as the rotational structure of all the branches of absorption or Raman spectra are well resolved. The evolution of basic ideas of line broadening and interference (spectral exchange) is reviewed. Adiabatic and non-adiabatic spectral broadening are described in the frame of binary non-Markovian theory and compared with the impact approximation. The conditions for spectral collapse and subsequent narrowing of the spectra are analysed for the simplest examples, which model typical situations in atomic and molecular spectroscopy. Special attention is paid to collapse of the isotropic Raman spectrum. Quantum theory, based on first principles, attempts to predict the. /-dependence of the widths of the rotational component as well as the envelope of the unresolved and then collapsed spectrum (Fig. 0.4). 

A simpler version of Hollas s book is now available in the Royal Society of Chemistry s new Tutorial Chemistry Texts series Basic Atomic and Molecular Spectroscopy, J. Michael Hollas, RSC, Cambridge, 2002. It gives a super introduction, and its academic level is well gauged, although it does require a knowledge of molecular orbitals and maths. 

What was the distinction between quantum chemistry and chemical physics After the Journal of Chemical Physics was established, it was easy to say that chemical physics was anything found in the new journal. This included molecular spectroscopy and molecular structures, the quantum mechanical treatment of electronic structure of molecules and crystals and the problem of chemical binding, the kinetics of chemical reactions from the standpoint of basic physical principles, the thermodynamic properties of substances and calculation by statistical mechanical methods, the structure of crystals, and surface phenomena. 

Correlation times and activation energy parameters obtained from different techniques may or may not agree with one another. Comparison of these data enables one to check the applicability of the model employed and examine whether any particular basic molecular process is reflected by the measurement or whether the method of analysis employed is correct. In order to characterize rotational motion in plastic crystals properly it may indeed be necessary to compare correlation times obtained by several methods. Thus, values from NMR spectroscopy and Rayleigh scattering enable us to distinguish uncorrelated and correlated rotations. Molecular disorder is not reflected in NMR measurements to this end, diffraction studies would be essential. 

Main Croup Chemistry W Henderson d- and f-Block Chemistry C J Jones Slructure and Bonding J BarrelI Functional Group Chemistry J R Hanson Organotransilion Metal Chemistry A F Hill Heterocyclic Chemistry M Sainsbury Atomic Structure and Periodicity J BarrelI Thermodynamics and Statistical Mechanics J M Seddon and J D Gale Basic Atomic and Molecular Spectroscopy J M Hollas... 

Manager of Chemical Physics Department. Responsible for planning and execution of basic research program involving staff of 27 with 16 professionals, whose research fields included polymer physics, surface chemistry, molecular spectroscopy, magnetic resonance, quantum chemistry, radiochemistry, and radiation chemistry. 

Photoelectron spectroscopy is a sort of molecular spectroscopy which is based on the photoionization process. Several outstanding books have been published on the subject so basic principles are only briefly outlined here. 

Let us investigate the situation in molecular spectroscopy. As the basic example we take the paper on the emission spectrum of hydrogen fluoride by Mann, Thrush, Lide, Ball, and Acquista,1 in which a given vibra-tion/rotation band is analyzed with the relation... 

Despite the fact that signals from molecules may be coming from thousands of light years away, a quantitative analysis can be performed on interstellar gas through the use of radio telescopes and their remote sensing capabilities. Such telescopes at first glance may seem an odd tool for a chemist, but these instruments basically exploit fundamental principles of molecular spectroscopy in a manner similar, but not identical, to a laboratory spectrometer. 

The chapters on the quantum mechanics of simple systems have been retained with only minor revisions, while the chapter on the covalent bond has been extended to include a description of molecular energy levels. The basic ideas of group theory are introduced here and illustrated by constructing symmetry-adapted molecular orbitals for simple molecules. There is a new chapter on atomic spectroscopy the chapter on molecular spectroscopy has been expanded and reorganized. 

This basically concludes the presentation of the current state of three-dimensional models in molecular spectroscopy. Needless to say, from an algebraic standpoint many aspects still must be considered to compete this topic. First, molecular equilibrium shapes other than the linear... 

As stated earlier on several occasions, the algebraic method should not be viewed on a mere mimicking of other well-established approaches to solving molecular spectroscopy problems. However, one could have just such an impression if the problems are limited to very simple cases that can be addressed equally well by traditional methods and do not carry the embarrassing burden of Lie algebras or Racah s tensor calculus. Nonetheless, every introductory article must start with simple examples and only then proceed to more complex ones. Sections III.C.2 and IV.B reveal the algebraic approach as capable of providing reliable and alternative solutions to nontrivial questions. Here alternative means in a faster way and with fewer arbitrary parameters. In this section we basically... 

Svanberg S (1992) Atomic and molecular spectroscopy - basic aspects and practical applications. Springer, Berlin Heidelberg New York London Paris Tokyo Hong Kong Barcelona Budapest, p 329... 

The primary object of Raman spectroscopy is the determination of molecular energy levels and transition probabilities connected with molecular transitions that are not accessible to infrared spectroscopy. Linear laser Raman spectroscopy, CARS, and hyper-Raman scattering have very successfully collected many spectroscopic data that could not have been obtained with other techniques. Besides these basic applications to molecular spectroscopy there are, however, a number of scientific and technical applications of Raman spectroscopy to other fields, which have become feasible with the new methods discussed in the previous sections. We can give only a few examples. 

Hollas, J. M., Basic Atomic and Molecular Spectroscopy, Wiley, Chichester, UK, 2002. 

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