Molecular spectroscopy high resolution

A number of halogenomethanes have been subjected to other forms of molecular spectroscopy. High-resolution Stark spectra of several transitions of the V3 band of CH3F have been studied by means of a CO2 laser measurements of the hyperfine structure on certain rotational transitions in CH2F2 have been made using a molecular beam maser spectrometer the millimetre-wave spectrum of ground-state CDCla and the microwave spectrum of CD3I in excited vibrational states have also been observed. 

I have not included in the bibliography my own books on spectroscopy. High Resolution Spectroscopy, second edition (John Wiley, 1998) follows the general format of Modern Spectroscopy but takes the subject to the research level. Basic Atomic and Molecular... 

Although the quadrupole moment is relatively small, N NMR spectroscopy is dominated by quadrupolar relaxation. The linewidths of the signals vary greatly because they depend on the nitrogen bond type and the molecular mobility. High-resolution work is possible only if the local electronic symmetry and the mobility are both high. 

Samples isolated by the HPLC may be further characterized by either electron impact or tandem mass spectroscopy. High-resolution mass spectroscopic analysis of a-tocotrienol shows a molecular ion peak M+ at m/z 424, which corresponds to the molecular formula C29H44O2. Fragmentation peaks, m/z 205 (C13H17O2) and m/z 203 (C13H15O2) are formed after the loss of the phytyl chain. The (3-, y-, and 5-tocotiienols show corresponding M+ peaks at 410, 410, and 396, respectively. 

A detailed understanding of both the solid state and surface chemistry has been gready assisted by improved characterization techniques (including X-ray absorption spectroscopy, high resolution electron microscopy, 3D-NMR spectroscopy, and others) and new molecular modeling methods. 

In conclusion, laser desorption in combination with molecular beam high-resolution spectroscopic methods has enabled the structural characterization of gas-phase biomolecules of significant size. Moreover, IR-UV ion dip spectroscopy offers information about the number and types of conformers present. Applications to diverse classes of biomolecular systems such as peptides, carbohydrates and nucleobases, are described in the various chapters of this book. 

Although much of the book focuses on physical theory, 1 have emphasized aspects of optical spectroscopy that are especially pertinent to molecular biophysics, and 1 have drawn most of the examples from this area. The book therefore covers topics that receive little attention in most general books on molecular spectroscopy, including exciton interactions, resonance energy transfer, single molecule spectroscopy, high-resolution fluorescence microscopy, femtosecond pump-probe spectroscopy, and photon echoes. It says less than is customary about atomic spectroscopy and about rotational and vibrational spectroscopy of... 

Quack M 1993 Molecular quantum dynamics from high resolution spectroscopy and laser chemistry J. Mol. Struct. 292 171-95... 

Quack M 1992 Time dependent intramolecular quantum dynamics from high resolution spectroscopy and laser chemistry Time Dependent Quantum Molecular Dynamics Experiment and Theory. Proc. NATO ARW 019/92 (NATO ASI Ser. Vol 299) ed J Broeckhove and L Lathouwers (New York Plenum) pp 293-310... 

Muller-Dethlefs K and Schlag E W 1991 High resolution zero kinetic energy (ZEKE) photoelectron spectroscopy of molecular systems Annu. Rev. Rhys. Chem. 42 109-36... 

The approach is ideally suited to the study of IVR on fast timescales, which is the most important primary process in imimolecular reactions. The application of high-resolution rovibrational overtone spectroscopy to this problem has been extensively demonstrated. Effective Hamiltonian analyses alone are insufficient, as has been demonstrated by explicit quantum dynamical models based on ab initio theory [95]. The fast IVR characteristic of the CH cliromophore in various molecular environments is probably the most comprehensively studied example of the kind [96] (see chapter A3.13). The importance of this question to chemical kinetics can perhaps best be illustrated with the following examples. The atom recombination reaction... 

New to the fourth edition are the topics of laser detection and ranging (LIDAR), cavity ring-down spectroscopy, femtosecond lasers and femtosecond spectroscopy, and the use of laser-induced fluorescence excitation for stmctural investigations of much larger molecules than had been possible previously. This latter technique takes advantage of two experimental quantum leaps the development of very high resolution lasers in the visible and ultraviolet regions and of the supersonic molecular beam. 

Analysis of Surface Molecular Composition. Information about the molecular composition of the surface or interface may also be of interest. A variety of methods for elucidating the nature of the molecules that exist on a surface or within an interface exist. Techniques based on vibrational spectroscopy of molecules are the most common and include the electron-based method of high resolution electron energy loss spectroscopy (hreels), and the optical methods of ftir and Raman spectroscopy. These tools are tremendously powerful methods of analysis because not only does a molecule possess vibrational modes which are signatures of that molecule, but the energies of molecular vibrations are extremely sensitive to the chemical environment in which a molecule is found. Thus, these methods direcdy provide information about the chemistry of the surface or interface through the vibrations of molecules contained on the surface or within the interface. 

Unlike the stable molecule N2O, the sulfur analogue N2S decomposes above 160 K. In the vapour phase N2S has been detected by high-resolution mass spectrometry. The IR spectrum is dominated by a very strong band at 2040 cm [v(NN)]. The first ionization potential has been determined by photoelectron spectroscopy to be 10.6 eV. " These data indicate that N2S resembles diazomethane, CH2N2, rather than N2O. It decomposes to give N2 and diatomic sulfur, S2, and, hence, elemental sulfur, rather than monoatomic sulfur. Ab initio molecular orbital calculations of bond lengths and bond energies for linear N2S indicate that the resonance structure N =N -S is dominant. 

Hartree-Fock wave functions, 269 High resolution electron energy loss spectroscopy, HREELS, 43, 69 Highest occupied molecular orbital, HOMO, 269... 

Advanced techniques like molecularly imprinted polymers (MIPs), infrared/near infrared spectroscopy (FT-IR/NIR), high resolution mass spectrometry, nuclear magnetic resonance (NMR), Raman spectroscopy, and biosensors will increasingly be applied for controlling food quality and safety. 

---