Proton-stretching vibrational mode

Abstract We present preliminary experimental results of inelastic X-ray scattering (IXS) on molecular vibrations of liquid H2O, DoO and the equimolar H>0 - D >0 mixture. The data analysis indicates the presence of an anomalous shortfall of scattering intensity from the O//-stretching vibrational modes. This effect has no explanation within the frame of conventional X-ray scattering theory. The possible connection of these observations with recent results of neutron and electron Compton scattering from protons in condensed matter is mentioned, as well as their interpretation in terms of attosecond entanglement. 

The acetylene-hydrogen cyanide complex is of particular interest in view of the fact that the C-H stretches of both monomers can be probed using the F-center laser. Earlier microwave studies of this system showed the existence of a T-shaped isomer S shown in Figure 3, in which the acetylene acts as the proton acceptor. During our infrared investigation of this species, a linear isomer was also found in which the acetylene now acts as the acid. By studying the two C-H stretch vibrational modes of these two isomers it is possible to learn a great deal about the anisotropy of the vibrational... 

Comparison with the modes of vibration of molecules given in Table I or with the LVM observed in proton implanted materials given in Table V and discussed in the next section clearly indicates that the LVMs observed in bulk material correspond to the stretching vibrations of P—H bonds in GaP and InP and As—H bonds in GaAs. It has to be noted that these lines are extremely sharp the FWHPs are in the 0.01-0.5 cm"1 range. For instance the line at 2202.4 cm"1 at 5 K in InP, which is shown in Fig. 19, has a FWHP of 0.015 cm"1, which could be instrument limited since the unapodized resolution limit of the interferometer used is 0.013 cm"1. 

After the ESIPT the molecule exhibits a pronounced ringing in this mode. The 295 cm-1 mode is a symmetric in-plane stretching vibration (see Fig. 3). The corresponding contraction of the molecule reduces the donor acceptor distances in both chelate rings simultaneously and initiates the electronic configuration change of the concerted ESIPT. The concerted double proton transfer leads therefore to a ringing of the molecule in this second mode. 

Fig. 3. Excitation of vibrational modes due to different reaction channels. Concerted double proton transfer leads to a symmetric stretching vibration and symmetry breaking single proton transfer to an antisymmetric bending motion. Damping of the vibrational motion by internal vibrational redistribution is indicated by IVR .

Cyanide is also an effective infrared probe (Yoshikawa et al., 1985). A drawback of this reagent as an infrared probe is its infrared intensity, which is much weaker than that of CO. However, as given in Fig. 10, the recent development in the infrared technique has solved this problem with the introduction of a mercury/cadmium/tellurium (MCT) detector (Fig. 10) (Yoshikawa et al., 1995). The C-N stretch vibrational band is sensitive to many factors, such as the oxidation state and species of the coordinating metal, the structures of porphyrin ring substituents, and the ligand trans to the cyanide and protein structure (Yoshikawa et al., 1985). This technique can be quite effectively applied for determination of the protonation state of the cyanide bound at a metal site. Possible binding modes of cyanide to a ferric iron are shown by Structures (1), (11), and (HI). Infrared spectroscopy is the best method for identihcation of these... 

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