Coherence spectroscopy high-resolution

Hepburn J W 1995 Generation of coherent vacuum ultraviolet radiation applications to high-resolution photoionization and photoelectron spectroscopy Laser Techniques in Chemistry vol 23, ed A B Myers and T R Rizzo (New York Wley) pp 149-83... 

Chemical shift correlated NMR experiments are the most valuable amongst the variety of high resolution NMR techniques designed to date. In the family of homonuclear techniques, four basic experiments are applied routinely to the structure elucidation of molecules of all sizes. The first two, COSY [1, 2] and TOCSY [3, 4], provide through bond connectivity information based on the coherent (J-couplings) transfer of polarization between spins. The other two, NOESY [5] and ROESY [6] reveal proximity of spins in space by making use of the incoherent polarization transfer (nuclear Overhauser effect, NOE). These two different polarization transfer mechanisms can be looked at as two complementary vehicles which allow us to move from one proton atom of a molecule to another proton atom this is the essence of a structure determination by the H NMR spectroscopy. 

Different schemes and recent results for high-resolution rotational coherence spectroscopy with picosecond and femtosecond laser pulses... 

Over the last years we have explored several advanced techniques for high-resolution rotational coherence spectroscopy (RCS [1]) in order to study the structures of molecules and clusters in the gas phase [2]. We have provided spectroscopic examples demonstrating (i) mass-selectivity (Fig. 1, [3]), (ii) that the rotational constants of the ground and electronic excited states can be obtained independently with high precision (lO MO"5, [4]), (iii) that the transition dipole moment alignment, (iv) centrifugal distortion constants, and (v) information on the polarizability tensor can be obtained (Fig.l, [5]). Here we review results pertaining to points (i), (ii), (iv) and (v) [2,3,5],... 

DilTcrcm schemes and recent results for high-resolution rotational coherence spectroscopy with picosecond and femtosecond laser pulses C. Kiehn, V.-V Matylitsky. A. Weiehert, M.-F. Gclin. W. Jar/eba and B Brutschy 73... 

Owyoung, A., "High Resolution Coherent Raman Spectroscopy of Gases", 4th International Conference on Laser Spectroscopy, Rottach-Egern, FRG, 11-15 June 1979. 

The advantages of the two coherent Raman techniques, stimulated Raman gain (SRGS) and inverse Raman spectroscopy (IRS), have been described in detail in Secs. 3.6.1.3 and 3.6.2.3. Here, we present an instructive example for each technique emphasizing the high resolution capability of the.se methods. 

Double-Quantum. (DQ) Proton Spectroscopy. Multiple-quantum (MQ) coherences are routinely used in high-resolution solution-state NMR spectroscopy. The MQ coherences cannot be observed directly and the application of two-dimensional methodology is required. The Double-Quantum (DQ) methodology is particularly useful to derive the information on the spatial proximity of different spins on the basis of the homonuclear dipolar couplings. ... 

Gas phase experiments are ideally suited for this since the perturbations induced by the local environment are completely eliminated, providing an ideal tool for exact measurements. Studies of coherent proton transfer of isolated molecules in the gas phase are able to yield absolute numbers on proton transfer tunneling without being influenced by solvent effects or the interaction of a crystal surrounding. Moreover, high resolution spectroscopy can yield state specific tunneling frequencies. These studies allow direct comparison with the results of ab initio studies and will therefore provide a sensitive test for recently developed theoretical methods. 

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